KVM系统调用说明

1. General description

----------------------

The kvm API is a set of ioctls that are issued to control various aspects

of a virtual machine. The ioctls belong to three classes

- System ioctls: These query and set global attributes which affect the

whole kvm subsystem. In addition a system ioctl is used to create

virtual machines

- VM ioctls: These query and set attributes that affect an entire virtual

machine, for example memory layout. In addition a VM ioctl is used to

create virtual cpus (vcpus).

Only run VM ioctls from the same process (address space) that was used

to create the VM.

- vcpu ioctls: These query and set attributes that control the operation

of a single virtual cpu.

Only run vcpu ioctls from the same thread that was used to create the

vcpu.

2. File descriptors

-------------------

The kvm API is centered around file descriptors. An initial

open("/dev/kvm") obtains a handle to the kvm subsystem; this handle

can be used to issue system ioctls. A KVM_CREATE_VM ioctl on this

handle will create a VM file descriptor which can be used to issue VM

ioctls. A KVM_CREATE_VCPU ioctl on a VM fd will create a virtual cpu

and return a file descriptor pointing to it. Finally, ioctls on a vcpu

fd can be used to control the vcpu, including the important task of

actually running guest code.

In general file descriptors can be migrated among processes by means

of fork() and the SCM_RIGHTS facility of unix domain socket. These

kinds of tricks are explicitly not supported by kvm. While they will

not cause harm to the host, their actual behavior is not guaranteed by

the API. The only supported use is one virtual machine per process,

and one vcpu per thread.

3. Extensions

-------------

As of Linux 2.6.22, the KVM ABI has been stabilized: no backward

incompatible change are allowed. However, there is an extension

facility that allows backward-compatible extensions to the API to be

queried and used.

The extension mechanism is not based on on the Linux version number.

Instead, kvm defines extension identifiers and a facility to query

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whether a particular extension identifier is available. If it is, a

set of ioctls is available for application use.

4. API description

------------------

This section describes ioctls that can be used to control kvm guests.

For each ioctl, the following information is provided along with a

description:

Capability: which KVM extension provides this ioctl. Can be 'basic',

which means that is will be provided by any kernel that supports

API version 12 (see section 4.1), or a KVM_CAP_xyz constant, which

means availability needs to be checked with KVM_CHECK_EXTENSION

(see section 4.4).

Architectures: which instruction set architectures provide this ioctl.

x86 includes both i386 and x86_64.

Type: system, vm, or vcpu.

Parameters: what parameters are accepted by the ioctl.

Returns: the return value. General error numbers (EBADF, ENOMEM, EINVAL)

are not detailed, but errors with specific meanings are.

4.1 KVM_GET_API_VERSION

Capability: basic

Architectures: all

Type: system ioctl

Parameters: none

Returns: the constant KVM_API_VERSION (=12)

This identifies the API version as the stable kvm API. It is not

expected that this number will change. However, Linux 2.6.20 and

2.6.21 report earlier versions; these are not documented and not

supported. Applications should refuse to run if KVM_GET_API_VERSION

returns a value other than 12. If this check passes, all ioctls

described as 'basic' will be available.

4.2 KVM_CREATE_VM

Capability: basic

Architectures: all

Type: system ioctl

Parameters: machine type identifier (KVM_VM_*)

Returns: a VM fd that can be used to control the new virtual machine.

The new VM has no virtual cpus and no memory. An mmap() of a VM fd

will access the virtual machine's physical address space; offset zero

corresponds to guest physical address zero. Use of mmap() on a VM fd

is discouraged if userspace memory allocation (KVM_CAP_USER_MEMORY) is

available.

You most certainly want to use 0 as machine type.

In order to create user controlled virtual machines on S390, check

KVM_CAP_S390_UCONTROL and use the flag KVM_VM_S390_UCONTROL as

privileged user (CAP_SYS_ADMIN).

4.3 KVM_GET_MSR_INDEX_LIST

Capability: basic

Architectures: x86

Type: system

Parameters: struct kvm_msr_list (in/out)

Returns: 0 on success; -1 on e

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rror

Errors:

E2BIG: the msr index list is to be to fit in the array specified by

the user.

struct kvm_msr_list {

__u32 nmsrs; /* number of msrs in entries */

__u32 indices[0];

};

This ioctl returns the guest msrs that are supported. The list varies

by kvm version and host processor, but does not change otherwise. The

user fills in the size of the indices array in nmsrs, and in return

kvm adjusts nmsrs to reflect the actual number of msrs and fills in

the indices array with their numbers.

Note: if kvm indicates supports MCE (KVM_CAP_MCE), then the MCE bank MSRs are

not returned in the MSR list, as different vcpus can have a different number

of banks, as set via the KVM_X86_SETUP_MCE ioctl.

4.4 KVM_CHECK_EXTENSION

Capability: basic

Architectures: all

Type: system ioctl

Parameters: extension identifier (KVM_CAP_*)

Returns: 0 if unsupported; 1 (or some other positive integer) if supported

The API allows the application to query about extensions to the core

kvm API. Userspace passes an extension identifier (an integer) and

receives an integer that describes the extension availability.

Generally 0 means no and 1 means yes, but some extensions may report

additional information in the integer return value.

4.5 KVM_GET_VCPU_MMAP_SIZE

Capability: basic

Architectures: all

Type: system ioctl

Parameters: none

Returns: size of vcpu mmap area, in bytes

The KVM_RUN ioctl (cf.) communicates with userspace via a shared

memory region. This ioctl returns the size of that region. See the

KVM_RUN documentation for details.

4.6 KVM_SET_MEMORY_REGION

Capability: basic

Architectures: all

Type: vm ioctl

Parameters: struct kvm_memory_region (in)

Returns: 0 on success, -1 on error

This ioctl is obsolete and has been removed.

4.7 KVM_CREATE_VCPU

Capability: basic

Architectures: all

Type: vm ioctl

Parameters: vcpu id (apic id on x86)

Returns: vcpu fd on success, -1 on error

This API adds a vcpu to a virtual machine. The vcpu id is a small integer

in the range [0, max_vcpus).

The recommended max_vcpus value can be retrieved using the KVM_CAP_NR_VCPUS of

the KVM_CHECK_EXTENSION ioctl() at run-time.

The maximum possible value for max_vcpus can be retrieved using the

KVM_CAP_MAX_VCPUS of the KVM_CHECK_EXTENSION ioctl() at run-time.

If the KVM_CAP_NR_VCPUS does not exist

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, you should assume that max_vcpus is 4

cpus max.

If the KVM_CAP_MAX_VCPUS does not exist, you should assume that max_vcpus is

same as the value returned from KVM_CAP_NR_VCPUS.

On powerpc using book3s_hv mode, the vcpus are mapped onto virtual

threads in one or more virtual CPU cores. (This is because the

hardware requires all the hardware threads in a CPU core to be in the

same partition.) The KVM_CAP_PPC_SMT capability indicates the number

of vcpus per virtual core (vcore). The vcore id is obtained by

dividing the vcpu id by the number of vcpus per vcore. The vcpus in a

given vcore will always be in the same physical core as each other

(though that might be a different physical core from time to time).

Userspace can control the threading (SMT) mode of the guest by its

allocation of vcpu ids. For example, if userspace wants

single-threaded guest vcpus, it should make all vcpu ids be a multiple

of the number of vcpus per vcore.

On powerpc using book3s_hv mode, the vcpus are mapped onto virtual

threads in one or more virtual CPU cores. (This is because the

hardware requires all the hardware threads in a CPU core to be in the

same partition.) The KVM_CAP_PPC_SMT capability indicates the number

of vcpus per virtual core (vcore). The vcore id is obtained by

dividing the vcpu id by the number of vcpus per vcore. The vcpus in a

given vcore will always be in the same physical core as each other

(though that might be a different physical core from time to time).

Userspace can control the threading (SMT) mode of the guest by its

allocation of vcpu ids. For example, if userspace wants

single-threaded guest vcpus, it should make all vcpu ids be a multiple

of the number of vcpus per vcore.

For virtual cpus that have been created with S390 user controlled virtual

machines, the resulting vcpu fd can be memory mapped at page offset

KVM_S390_SIE_PAGE_OFFSET in order to obtain a memory map of the virtual

cpu's hardware control block.

4.8 KVM_GET_DIRTY_LOG (vm ioctl)

Capability: basic

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_dirty_log (in/out)

Returns: 0 on success, -1 on error

/* for KVM_GET_DIRTY_LOG */

struct kvm_dirty_log {

__u32 slot;

__u32 padding;

union {

void __user *dirty_bitmap; /* one bit per page */

__u64 padding;

};

};

Given a memory slot, return a bitmap containing a

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ny pages dirtied

since the last call to this ioctl. Bit 0 is the first page in the

memory slot. Ensure the entire structure is cleared to avoid padding

issues.

4.9 KVM_SET_MEMORY_ALIAS

Capability: basic

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_memory_alias (in)

Returns: 0 (success), -1 (error)

This ioctl is obsolete and has been removed.

4.10 KVM_RUN

Capability: basic

Architectures: all

Type: vcpu ioctl

Parameters: none

Returns: 0 on success, -1 on error

Errors:

EINTR: an unmasked signal is pending

This ioctl is used to run a guest virtual cpu. While there are no

explicit parameters, there is an implicit parameter block that can be

obtained by mmap()ing the vcpu fd at offset 0, with the size given by

KVM_GET_VCPU_MMAP_SIZE. The parameter block is formatted as a 'struct

kvm_run' (see below).

4.11 KVM_GET_REGS

Capability: basic

Architectures: all

Type: vcpu ioctl

Parameters: struct kvm_regs (out)

Returns: 0 on success, -1 on error

Reads the general purpose registers from the vcpu.

/* x86 */

struct kvm_regs {

/* out (KVM_GET_REGS) / in (KVM_SET_REGS) */

__u64 rax, rbx, rcx, rdx;

__u64 rsi, rdi, rsp, rbp;

__u64 r8, r9, r10, r11;

__u64 r12, r13, r14, r15;

__u64 rip, rflags;

};

4.12 KVM_SET_REGS

Capability: basic

Architectures: all

Type: vcpu ioctl

Parameters: struct kvm_regs (in)

Returns: 0 on success, -1 on error

Writes the general purpose registers into the vcpu.

See KVM_GET_REGS for the data structure.

4.13 KVM_GET_SREGS

Capability: basic

Architectures: x86, ppc

Type: vcpu ioctl

Parameters: struct kvm_sregs (out)

Returns: 0 on success, -1 on error

Reads special registers from the vcpu.

/* x86 */

struct kvm_sregs {

struct kvm_segment cs, ds, es, fs, gs, ss;

struct kvm_segment tr, ldt;

struct kvm_dtable gdt, idt;

__u64 cr0, cr2, cr3, cr4, cr8;

__u64 efer;

__u64 apic_base;

__u64 interrupt_bitmap[(KVM_NR_INTERRUPTS + 63) / 64];

};

/* ppc -- see arch/powerpc/include/asm/kvm.h */

interrupt_bitmap is a bitmap of pending external interrupts. At most

one bit may be set. This interrupt has been acknowledged by the APIC

but not yet injected into the cpu core.

4.14 KVM_SET_SREGS

Capability: basic

Architectures: x86, ppc

Type: vcpu ioctl

Parameters: struct kvm_sregs (in)

Returns: 0 on success, -1 on err

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or

Writes special registers into the vcpu. See KVM_GET_SREGS for the

data structures.

4.15 KVM_TRANSLATE

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_translation (in/out)

Returns: 0 on success, -1 on error

Translates a virtual address according to the vcpu's current address

translation mode.

struct kvm_translation {

/* in */

__u64 linear_address;

/* out */

__u64 physical_address;

__u8 valid;

__u8 writeable;

__u8 usermode;

__u8 pad[5];

};

4.16 KVM_INTERRUPT

Capability: basic

Architectures: x86, ppc

Type: vcpu ioctl

Parameters: struct kvm_interrupt (in)

Returns: 0 on success, -1 on error

Queues a hardware interrupt vector to be injected. This is only

useful if in-kernel local APIC or equivalent is not used.

/* for KVM_INTERRUPT */

struct kvm_interrupt {

/* in */

__u32 irq;

};

X86:

Note 'irq' is an interrupt vector, not an interrupt pin or line.

PPC:

Queues an external interrupt to be injected. This ioctl is overleaded

with 3 different irq values:

a) KVM_INTERRUPT_SET

This injects an edge type external interrupt into the guest once it's ready

to receive interrupts. When injected, the interrupt is done.

b) KVM_INTERRUPT_UNSET

This unsets any pending interrupt.

Only available with KVM_CAP_PPC_UNSET_IRQ.

c) KVM_INTERRUPT_SET_LEVEL

This injects a level type external interrupt into the guest context. The

interrupt stays pending until a specific ioctl with KVM_INTERRUPT_UNSET

is triggered.

Only available with KVM_CAP_PPC_IRQ_LEVEL.

Note that any value for 'irq' other than the ones stated above is invalid

and incurs unexpected behavior.

4.17 KVM_DEBUG_GUEST

Capability: basic

Architectures: none

Type: vcpu ioctl

Parameters: none)

Returns: -1 on error

Support for this has been removed. Use KVM_SET_GUEST_DEBUG instead.

4.18 KVM_GET_MSRS

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_msrs (in/out)

Returns: 0 on success, -1 on error

Reads model-specific registers from the vcpu. Supported msr indices can

be obtained using KVM_GET_MSR_INDEX_LIST.

struct kvm_msrs {

__u32 nmsrs; /* number of msrs in entries */

__u32 pad;

struct kvm_msr_entry entries[0];

};

struct kvm_msr_entry {

__u32 index;

__u32 reserved;

__u64 data;

};

Applic

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ation code should set the 'nmsrs' member (which indicates the

size of the entries array) and the 'index' member of each array entry.

kvm will fill in the 'data' member.

4.19 KVM_SET_MSRS

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_msrs (in)

Returns: 0 on success, -1 on error

Writes model-specific registers to the vcpu. See KVM_GET_MSRS for the

data structures.

Application code should set the 'nmsrs' member (which indicates the

size of the entries array), and the 'index' and 'data' members of each

array entry.

4.20 KVM_SET_CPUID

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_cpuid (in)

Returns: 0 on success, -1 on error

Defines the vcpu responses to the cpuid instruction. Applications

should use the KVM_SET_CPUID2 ioctl if available.

struct kvm_cpuid_entry {

__u32 function;

__u32 eax;

__u32 ebx;

__u32 ecx;

__u32 edx;

__u32 padding;

};

/* for KVM_SET_CPUID */

struct kvm_cpuid {

__u32 nent;

__u32 padding;

struct kvm_cpuid_entry entries[0];

};

4.21 KVM_SET_SIGNAL_MASK

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_signal_mask (in)

Returns: 0 on success, -1 on error

Defines which signals are blocked during execution of KVM_RUN. This

signal mask temporarily overrides the threads signal mask. Any

unblocked signal received (except SIGKILL and SIGSTOP, which retain

their traditional behaviour) will cause KVM_RUN to return with -EINTR.

Note the signal will only be delivered if not blocked by the original

signal mask.

/* for KVM_SET_SIGNAL_MASK */

struct kvm_signal_mask {

__u32 len;

__u8 sigset[0];

};

4.22 KVM_GET_FPU

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_fpu (out)

Returns: 0 on success, -1 on error

Reads the floating point state from the vcpu.

/* for KVM_GET_FPU and KVM_SET_FPU */

struct kvm_fpu {

__u8 fpr[8][16];

__u16 fcw;

__u16 fsw;

__u8 ftwx; /* in fxsave format */

__u8 pad1;

__u16 last_opcode;

__u64 last_ip;

__u64 last_dp;

__u8 xmm[16][16];

__u32 mxcsr;

__u32 pad2;

};

4.23 KVM_SET_FPU

Capability: basic

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_fpu (in)

Returns: 0 on success, -1 on error

Writes the floating point state to the vcpu.

/* for KVM_GET_FPU a

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nd KVM_SET_FPU */

struct kvm_fpu {

__u8 fpr[8][16];

__u16 fcw;

__u16 fsw;

__u8 ftwx; /* in fxsave format */

__u8 pad1;

__u16 last_opcode;

__u64 last_ip;

__u64 last_dp;

__u8 xmm[16][16];

__u32 mxcsr;

__u32 pad2;

};

4.24 KVM_CREATE_IRQCHIP

Capability: KVM_CAP_IRQCHIP

Architectures: x86, ia64

Type: vm ioctl

Parameters: none

Returns: 0 on success, -1 on error

Creates an interrupt controller model in the kernel. On x86, creates a virtual

ioapic, a virtual PIC (two PICs, nested), and sets up future vcpus to have a

local APIC. IRQ routing for GSIs 0-15 is set to both PIC and IOAPIC; GSI 16-23

only go to the IOAPIC. On ia64, a IOSAPIC is created.

4.25 KVM_IRQ_LINE

Capability: KVM_CAP_IRQCHIP

Architectures: x86, ia64

Type: vm ioctl

Parameters: struct kvm_irq_level

Returns: 0 on success, -1 on error

Sets the level of a GSI input to the interrupt controller model in the kernel.

Requires that an interrupt controller model has been previously created with

KVM_CREATE_IRQCHIP. Note that edge-triggered interrupts require the level

to be set to 1 and then back to 0.

struct kvm_irq_level {

union {

__u32 irq; /* GSI */

__s32 status; /* not used for KVM_IRQ_LEVEL */

};

__u32 level; /* 0 or 1 */

};

4.26 KVM_GET_IRQCHIP

Capability: KVM_CAP_IRQCHIP

Architectures: x86, ia64

Type: vm ioctl

Parameters: struct kvm_irqchip (in/out)

Returns: 0 on success, -1 on error

Reads the state of a kernel interrupt controller created with

KVM_CREATE_IRQCHIP into a buffer provided by the caller.

struct kvm_irqchip {

__u32 chip_id; /* 0 = PIC1, 1 = PIC2, 2 = IOAPIC */

__u32 pad;

union {

char dummy[512]; /* reserving space */

struct kvm_pic_state pic;

struct kvm_ioapic_state ioapic;

} chip;

};

4.27 KVM_SET_IRQCHIP

Capability: KVM_CAP_IRQCHIP

Architectures: x86, ia64

Type: vm ioctl

Parameters: struct kvm_irqchip (in)

Returns: 0 on success, -1 on error

Sets the state of a kernel interrupt controller created with

KVM_CREATE_IRQCHIP from a buffer provided by the caller.

struct kvm_irqchip {

__u32 chip_id; /* 0 = PIC1, 1 = PIC2, 2 = IOAPIC */

__u32 pad;

union {

char dummy[512]; /* reserving space */

struct kvm_pic_state pic;

struct kvm_ioapic_state ioapic;

} chip;

};

4.28 KVM_XEN_HVM_CONFIG

Capability: KVM_CA

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P_XEN_HVM

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_xen_hvm_config (in)

Returns: 0 on success, -1 on error

Sets the MSR that the Xen HVM guest uses to initialize its hypercall

page, and provides the starting address and size of the hypercall

blobs in userspace. When the guest writes the MSR, kvm copies one

page of a blob (32- or 64-bit, depending on the vcpu mode) to guest

memory.

struct kvm_xen_hvm_config {

__u32 flags;

__u32 msr;

__u64 blob_addr_32;

__u64 blob_addr_64;

__u8 blob_size_32;

__u8 blob_size_64;

__u8 pad2[30];

};

4.29 KVM_GET_CLOCK

Capability: KVM_CAP_ADJUST_CLOCK

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_clock_data (out)

Returns: 0 on success, -1 on error

Gets the current timestamp of kvmclock as seen by the current guest. In

conjunction with KVM_SET_CLOCK, it is used to ensure monotonicity on scenarios

such as migration.

struct kvm_clock_data {

__u64 clock; /* kvmclock current value */

__u32 flags;

__u32 pad[9];

};

4.30 KVM_SET_CLOCK

Capability: KVM_CAP_ADJUST_CLOCK

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_clock_data (in)

Returns: 0 on success, -1 on error

Sets the current timestamp of kvmclock to the value specified in its parameter.

In conjunction with KVM_GET_CLOCK, it is used to ensure monotonicity on scenarios

such as migration.

struct kvm_clock_data {

__u64 clock; /* kvmclock current value */

__u32 flags;

__u32 pad[9];

};

4.31 KVM_GET_VCPU_EVENTS

Capability: KVM_CAP_VCPU_EVENTS

Extended by: KVM_CAP_INTR_SHADOW

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_vcpu_event (out)

Returns: 0 on success, -1 on error

Gets currently pending exceptions, interrupts, and NMIs as well as related

states of the vcpu.

struct kvm_vcpu_events {

struct {

__u8 injected;

__u8 nr;

__u8 has_error_code;

__u8 pad;

__u32 error_code;

} exception;

struct {

__u8 injected;

__u8 nr;

__u8 soft;

__u8 shadow;

} interrupt;

struct {

__u8 injected;

__u8 pending;

__u8 masked;

__u8 pad;

} nmi;

__u32 sipi_vector;

__u32 flags;

};

KVM_VCPUEVENT_VALID_SHADOW may be set in the flags field to signal that

interrupt.shadow contains a valid state. Otherwise, this field is undefined.

4.32 KVM_SET_VCPU_EVENTS

Capability: KVM_CAP_VCPU_EVENTS

Extended by: KVM_CAP_

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INTR_SHADOW

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_vcpu_event (in)

Returns: 0 on success, -1 on error

Set pending exceptions, interrupts, and NMIs as well as related states of the

vcpu.

See KVM_GET_VCPU_EVENTS for the data structure.

Fields that may be modified asynchronously by running VCPUs can be excluded

from the update. These fields are nmi.pending and sipi_vector. Keep the

corresponding bits in the flags field cleared to suppress overwriting the

current in-kernel state. The bits are:

KVM_VCPUEVENT_VALID_NMI_PENDING - transfer nmi.pending to the kernel

KVM_VCPUEVENT_VALID_SIPI_VECTOR - transfer sipi_vector

If KVM_CAP_INTR_SHADOW is available, KVM_VCPUEVENT_VALID_SHADOW can be set in

the flags field to signal that interrupt.shadow contains a valid state and

shall be written into the VCPU.

4.33 KVM_GET_DEBUGREGS

Capability: KVM_CAP_DEBUGREGS

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_debugregs (out)

Returns: 0 on success, -1 on error

Reads debug registers from the vcpu.

struct kvm_debugregs {

__u64 db[4];

__u64 dr6;

__u64 dr7;

__u64 flags;

__u64 reserved[9];

};

4.34 KVM_SET_DEBUGREGS

Capability: KVM_CAP_DEBUGREGS

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_debugregs (in)

Returns: 0 on success, -1 on error

Writes debug registers into the vcpu.

See KVM_GET_DEBUGREGS for the data structure. The flags field is unused

yet and must be cleared on entry.

4.35 KVM_SET_USER_MEMORY_REGION

Capability: KVM_CAP_USER_MEM

Architectures: all

Type: vm ioctl

Parameters: struct kvm_userspace_memory_region (in)

Returns: 0 on success, -1 on error

struct kvm_userspace_memory_region {

__u32 slot;

__u32 flags;

__u64 guest_phys_addr;

__u64 memory_size; /* bytes */

__u64 userspace_addr; /* start of the userspace allocated memory */

};

/* for kvm_memory_region::flags */

#define KVM_MEM_LOG_DIRTY_PAGES (1UL << 0)

#define KVM_MEM_READONLY (1UL << 1)

This ioctl allows the user to create or modify a guest physical memory

slot. When changing an existing slot, it may be moved in the guest

physical memory space, or its flags may be modified. It may not be

resized. Slots may not overlap in guest physical address space.

Memory for the region is taken starting at the address denoted by the

field userspace_addr, which must point at u

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ser addressable memory for

the entire memory slot size. Any object may back this memory, including

anonymous memory, ordinary files, and hugetlbfs.

It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr

be identical. This allows large pages in the guest to be backed by large

pages in the host.

The flags field supports two flag, KVM_MEM_LOG_DIRTY_PAGES, which instructs

kvm to keep track of writes to memory within the slot. See KVM_GET_DIRTY_LOG

ioctl. The KVM_CAP_READONLY_MEM capability indicates the availability of the

KVM_MEM_READONLY flag. When this flag is set for a memory region, KVM only

allows read accesses. Writes will be posted to userspace as KVM_EXIT_MMIO

exits.

When the KVM_CAP_SYNC_MMU capability is available, changes in the backing of

the memory region are automatically reflected into the guest. For example, an

mmap() that affects the region will be made visible immediately. Another

example is madvise(MADV_DROP).

It is recommended to use this API instead of the KVM_SET_MEMORY_REGION ioctl.

The KVM_SET_MEMORY_REGION does not allow fine grained control over memory

allocation and is deprecated.

4.36 KVM_SET_TSS_ADDR

Capability: KVM_CAP_SET_TSS_ADDR

Architectures: x86

Type: vm ioctl

Parameters: unsigned long tss_address (in)

Returns: 0 on success, -1 on error

This ioctl defines the physical address of a three-page region in the guest

physical address space. The region must be within the first 4GB of the

guest physical address space and must not conflict with any memory slot

or any mmio address. The guest may malfunction if it accesses this memory

region.

This ioctl is required on Intel-based hosts. This is needed on Intel hardware

because of a quirk in the virtualization implementation (see the internals

documentation when it pops into existence).

4.37 KVM_ENABLE_CAP

Capability: KVM_CAP_ENABLE_CAP

Architectures: ppc

Type: vcpu ioctl

Parameters: struct kvm_enable_cap (in)

Returns: 0 on success; -1 on error

+Not all extensions are enabled by default. Using this ioctl the application

can enable an extension, making it available to the guest.

On systems that do not support this ioctl, it always fails. On systems that

do support it, it only works for extensions that are supported for enablement.

To check if a capability can be enabled, the KVM_CHEC

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K_EXTENSION ioctl should

be used.

struct kvm_enable_cap {

/* in */

__u32 cap;

The capability that is supposed to get enabled.

__u32 flags;

A bitfield indicating future enhancements. Has to be 0 for now.

__u64 args[4];

Arguments for enabling a feature. If a feature needs initial values to

function properly, this is the place to put them.

__u8 pad[64];

};

4.38 KVM_GET_MP_STATE

Capability: KVM_CAP_MP_STATE

Architectures: x86, ia64

Type: vcpu ioctl

Parameters: struct kvm_mp_state (out)

Returns: 0 on success; -1 on error

struct kvm_mp_state {

__u32 mp_state;

};

Returns the vcpu's current "multiprocessing state" (though also valid on

uniprocessor guests).

Possible values are:

- KVM_MP_STATE_RUNNABLE: the vcpu is currently running

- KVM_MP_STATE_UNINITIALIZED: the vcpu is an application processor (AP)

which has not yet received an INIT signal

- KVM_MP_STATE_INIT_RECEIVED: the vcpu has received an INIT signal, and is

now ready for a SIPI

- KVM_MP_STATE_HALTED: the vcpu has executed a HLT instruction and

is waiting for an interrupt

- KVM_MP_STATE_SIPI_RECEIVED: the vcpu has just received a SIPI (vector

accessible via KVM_GET_VCPU_EVENTS)

This ioctl is only useful after KVM_CREATE_IRQCHIP. Without an in-kernel

irqchip, the multiprocessing state must be maintained by userspace.

4.39 KVM_SET_MP_STATE

Capability: KVM_CAP_MP_STATE

Architectures: x86, ia64

Type: vcpu ioctl

Parameters: struct kvm_mp_state (in)

Returns: 0 on success; -1 on error

Sets the vcpu's current "multiprocessing state"; see KVM_GET_MP_STATE for

arguments.

This ioctl is only useful after KVM_CREATE_IRQCHIP. Without an in-kernel

irqchip, the multiprocessing state must be maintained by userspace.

4.40 KVM_SET_IDENTITY_MAP_ADDR

Capability: KVM_CAP_SET_IDENTITY_MAP_ADDR

Architectures: x86

Type: vm ioctl

Parameters: unsigned long identity (in)

Returns: 0 on success, -1 on error

This ioctl defines the physical address of a one-page region in the guest

physical address space. The region must be within the first 4GB of the

guest physical address space and must not conflict with any memory slot

or any mmio address.

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The guest may malfunction if it accesses this memory

region.

This ioctl is required on Intel-based hosts. This is needed on Intel hardware

because of a quirk in the virtualization implementation (see the internals

documentation when it pops into existence).

4.41 KVM_SET_BOOT_CPU_ID

Capability: KVM_CAP_SET_BOOT_CPU_ID

Architectures: x86, ia64

Type: vm ioctl

Parameters: unsigned long vcpu_id

Returns: 0 on success, -1 on error

Define which vcpu is the Bootstrap Processor (BSP). Values are the same

as the vcpu id in KVM_CREATE_VCPU. If this ioctl is not called, the default

is vcpu 0.

4.42 KVM_GET_XSAVE

Capability: KVM_CAP_XSAVE

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_xsave (out)

Returns: 0 on success, -1 on error

struct kvm_xsave {

__u32 region[1024];

};

This ioctl would copy current vcpu's xsave struct to the userspace.

4.43 KVM_SET_XSAVE

Capability: KVM_CAP_XSAVE

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_xsave (in)

Returns: 0 on success, -1 on error

struct kvm_xsave {

__u32 region[1024];

};

This ioctl would copy userspace's xsave struct to the kernel.

4.44 KVM_GET_XCRS

Capability: KVM_CAP_XCRS

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_xcrs (out)

Returns: 0 on success, -1 on error

struct kvm_xcr {

__u32 xcr;

__u32 reserved;

__u64 value;

};

struct kvm_xcrs {

__u32 nr_xcrs;

__u32 flags;

struct kvm_xcr xcrs[KVM_MAX_XCRS];

__u64 padding[16];

};

This ioctl would copy current vcpu's xcrs to the userspace.

4.45 KVM_SET_XCRS

Capability: KVM_CAP_XCRS

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_xcrs (in)

Returns: 0 on success, -1 on error

struct kvm_xcr {

__u32 xcr;

__u32 reserved;

__u64 value;

};

struct kvm_xcrs {

__u32 nr_xcrs;

__u32 flags;

struct kvm_xcr xcrs[KVM_MAX_XCRS];

__u64 padding[16];

};

This ioctl would set vcpu's xcr to the value userspace specified.

4.46 KVM_GET_SUPPORTED_CPUID

Capability: KVM_CAP_EXT_CPUID

Architectures: x86

Type: system ioctl

Parameters: struct kvm_cpuid2 (in/out)

Returns: 0 on success, -1 on error

struct kvm_cpuid2 {

__u32 nent;

__u32 padding;

struct kvm_cpuid_entry2 entries[0];

};

#define KVM_CPUID_FLAG_SIGNIFCANT_INDEX 1

#define KVM_CPUID_FLAG_STATEFUL_FUNC 2

#define KVM_CPUID_FLAG_STATE_READ_NEXT

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4

struct kvm_cpuid_entry2 {

__u32 function;

__u32 index;

__u32 flags;

__u32 eax;

__u32 ebx;

__u32 ecx;

__u32 edx;

__u32 padding[3];

};

This ioctl returns x86 cpuid features which are supported by both the hardware

and kvm. Userspace can use the information returned by this ioctl to

construct cpuid information (for KVM_SET_CPUID2) that is consistent with

hardware, kernel, and userspace capabilities, and with user requirements (for

example, the user may wish to constrain cpuid to emulate older hardware,

or for feature consistency across a cluster).

Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure

with the 'nent' field indicating the number of entries in the variable-size

array 'entries'. If the number of entries is too low to describe the cpu

capabilities, an error (E2BIG) is returned. If the number is too high,

the 'nent' field is adjusted and an error (ENOMEM) is returned. If the

number is just right, the 'nent' field is adjusted to the number of valid

entries in the 'entries' array, which is then filled.

The entries returned are the host cpuid as returned by the cpuid instruction,

with unknown or unsupported features masked out. Some features (for example,

x2apic), may not be present in the host cpu, but are exposed by kvm if it can

emulate them efficiently. The fields in each entry are defined as follows:

function: the eax value used to obtain the entry

index: the ecx value used to obtain the entry (for entries that are

affected by ecx)

flags: an OR of zero or more of the following:

KVM_CPUID_FLAG_SIGNIFCANT_INDEX:

if the index field is valid

KVM_CPUID_FLAG_STATEFUL_FUNC:

if cpuid for this function returns different values for successive

invocations; there will be several entries with the same function,

all with this flag set

KVM_CPUID_FLAG_STATE_READ_NEXT:

for KVM_CPUID_FLAG_STATEFUL_FUNC entries, set if this entry is

the first entry to be read by a cpu

eax, ebx, ecx, edx: the values returned by the cpuid instruction for

this function/index combination

The TSC deadline timer feature (CPUID leaf 1, ecx[24]) is always returned

as false, since the feature depends on KVM_CREATE_IRQCHIP for local APIC

support. Instead it is reported via

ioctl(

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KVM_CHECK_EXTENSION, KVM_CAP_TSC_DEADLINE_TIMER)

if that returns true and you use KVM_CREATE_IRQCHIP, or if you emulate the

feature in userspace, then you can enable the feature for KVM_SET_CPUID2.

4.47 KVM_PPC_GET_PVINFO

Capability: KVM_CAP_PPC_GET_PVINFO

Architectures: ppc

Type: vm ioctl

Parameters: struct kvm_ppc_pvinfo (out)

Returns: 0 on success, !0 on error

struct kvm_ppc_pvinfo {

__u32 flags;

__u32 hcall[4];

__u8 pad[108];

};

This ioctl fetches PV specific information that need to be passed to the guest

using the device tree or other means from vm context.

The hcall array defines 4 instructions that make up a hypercall.

If any additional field gets added to this structure later on, a bit for that

additional piece of information will be set in the flags bitmap.

The flags bitmap is defined as:

/* the host supports the ePAPR idle hcall

#define KVM_PPC_PVINFO_FLAGS_EV_IDLE (1<<0)

4.48 KVM_ASSIGN_PCI_DEVICE

Capability: KVM_CAP_DEVICE_ASSIGNMENT

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_assigned_pci_dev (in)

Returns: 0 on success, -1 on error

Assigns a host PCI device to the VM.

struct kvm_assigned_pci_dev {

__u32 assigned_dev_id;

__u32 busnr;

__u32 devfn;

__u32 flags;

__u32 segnr;

union {

__u32 reserved[11];

};

};

The PCI device is specified by the triple segnr, busnr, and devfn.

Identification in succeeding service requests is done via assigned_dev_id. The

following flags are specified:

/* Depends on KVM_CAP_IOMMU */

#define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)

/* The following two depend on KVM_CAP_PCI_2_3 */

#define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1)

#define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)

If KVM_DEV_ASSIGN_PCI_2_3 is set, the kernel will manage legacy INTx interrupts

via the PCI-2.3-compliant device-level mask, thus enable IRQ sharing with other

assigned devices or host devices. KVM_DEV_ASSIGN_MASK_INTX specifies the

guest's view on the INTx mask, see KVM_ASSIGN_SET_INTX_MASK for details.

The KVM_DEV_ASSIGN_ENABLE_IOMMU flag is a mandatory option to ensure

isolation of the device. Usages not specifying this flag are deprecated.

Only PCI header type 0 devices with PCI BAR resources are supported by

device assignment. The user requesting this ioctl must have read/write

access to the PCI sysfs resource files associated wi

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th the device.

4.49 KVM_DEASSIGN_PCI_DEVICE

Capability: KVM_CAP_DEVICE_DEASSIGNMENT

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_assigned_pci_dev (in)

Returns: 0 on success, -1 on error

Ends PCI device assignment, releasing all associated resources.

See KVM_CAP_DEVICE_ASSIGNMENT for the data structure. Only assigned_dev_id is

used in kvm_assigned_pci_dev to identify the device.

4.50 KVM_ASSIGN_DEV_IRQ

Capability: KVM_CAP_ASSIGN_DEV_IRQ

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_assigned_irq (in)

Returns: 0 on success, -1 on error

Assigns an IRQ to a passed-through device.

struct kvm_assigned_irq {

__u32 assigned_dev_id;

__u32 host_irq; /* ignored (legacy field) */

__u32 guest_irq;

__u32 flags;

union {

__u32 reserved[12];

};

};

The following flags are defined:

#define KVM_DEV_IRQ_HOST_INTX (1 << 0)

#define KVM_DEV_IRQ_HOST_MSI (1 << 1)

#define KVM_DEV_IRQ_HOST_MSIX (1 << 2)

#define KVM_DEV_IRQ_GUEST_INTX (1 << 8)

#define KVM_DEV_IRQ_GUEST_MSI (1 << 9)

#define KVM_DEV_IRQ_GUEST_MSIX (1 << 10)

It is not valid to specify multiple types per host or guest IRQ. However, the

IRQ type of host and guest can differ or can even be null.

4.51 KVM_DEASSIGN_DEV_IRQ

Capability: KVM_CAP_ASSIGN_DEV_IRQ

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_assigned_irq (in)

Returns: 0 on success, -1 on error

Ends an IRQ assignment to a passed-through device.

See KVM_ASSIGN_DEV_IRQ for the data structure. The target device is specified

by assigned_dev_id, flags must correspond to the IRQ type specified on

KVM_ASSIGN_DEV_IRQ. Partial deassignment of host or guest IRQ is allowed.

4.52 KVM_SET_GSI_ROUTING

Capability: KVM_CAP_IRQ_ROUTING

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_irq_routing (in)

Returns: 0 on success, -1 on error

Sets the GSI routing table entries, overwriting any previously set entries.

struct kvm_irq_routing {

__u32 nr;

__u32 flags;

struct kvm_irq_routing_entry entries[0];

};

No flags are specified so far, the corresponding field must be set to zero.

struct kvm_irq_routing_entry {

__u32 gsi;

__u32 type;

__u32 flags;

__u32 pad;

union {

struct kvm_irq_routing_irqchip irqchip;

struct kvm_irq_routing_msi msi;

__u32 pad[8];

} u;

};

/* gsi routin

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g entry types */

#define KVM_IRQ_ROUTING_IRQCHIP 1

#define KVM_IRQ_ROUTING_MSI 2

No flags are specified so far, the corresponding field must be set to zero.

struct kvm_irq_routing_irqchip {

__u32 irqchip;

__u32 pin;

};

struct kvm_irq_routing_msi {

__u32 address_lo;

__u32 address_hi;

__u32 data;

__u32 pad;

};

4.53 KVM_ASSIGN_SET_MSIX_NR

Capability: KVM_CAP_DEVICE_MSIX

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_assigned_msix_nr (in)

Returns: 0 on success, -1 on error

Set the number of MSI-X interrupts for an assigned device. The number is

reset again by terminating the MSI-X assignment of the device via

KVM_DEASSIGN_DEV_IRQ. Calling this service more than once at any earlier

point will fail.

struct kvm_assigned_msix_nr {

__u32 assigned_dev_id;

__u16 entry_nr;

__u16 padding;

};

#define KVM_MAX_MSIX_PER_DEV 256

4.54 KVM_ASSIGN_SET_MSIX_ENTRY

Capability: KVM_CAP_DEVICE_MSIX

Architectures: x86 ia64

Type: vm ioctl

Parameters: struct kvm_assigned_msix_entry (in)

Returns: 0 on success, -1 on error

Specifies the routing of an MSI-X assigned device interrupt to a GSI. Setting

the GSI vector to zero means disabling the interrupt.

struct kvm_assigned_msix_entry {

__u32 assigned_dev_id;

__u32 gsi;

__u16 entry; /* The index of entry in the MSI-X table */

__u16 padding[3];

};

4.55 KVM_SET_TSC_KHZ

Capability: KVM_CAP_TSC_CONTROL

Architectures: x86

Type: vcpu ioctl

Parameters: virtual tsc_khz

Returns: 0 on success, -1 on error

Specifies the tsc frequency for the virtual machine. The unit of the

frequency is KHz.

4.56 KVM_GET_TSC_KHZ

Capability: KVM_CAP_GET_TSC_KHZ

Architectures: x86

Type: vcpu ioctl

Parameters: none

Returns: virtual tsc-khz on success, negative value on error

Returns the tsc frequency of the guest. The unit of the return value is

KHz. If the host has unstable tsc this ioctl returns -EIO instead as an

error.

4.57 KVM_GET_LAPIC

Capability: KVM_CAP_IRQCHIP

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_lapic_state (out)

Returns: 0 on success, -1 on error

#define KVM_APIC_REG_SIZE 0x400

struct kvm_lapic_state {

char regs[KVM_APIC_REG_SIZE];

};

Reads the Local APIC registers and copies them into the input argument. The

data format and layout are the same as documented in the architecture manual

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.

4.58 KVM_SET_LAPIC

Capability: KVM_CAP_IRQCHIP

Architectures: x86

Type: vcpu ioctl

Parameters: struct kvm_lapic_state (in)

Returns: 0 on success, -1 on error

#define KVM_APIC_REG_SIZE 0x400

struct kvm_lapic_state {

char regs[KVM_APIC_REG_SIZE];

};

Copies the input argument into the the Local APIC registers. The data format

and layout are the same as documented in the architecture manual.

4.59 KVM_IOEVENTFD

Capability: KVM_CAP_IOEVENTFD

Architectures: all

Type: vm ioctl

Parameters: struct kvm_ioeventfd (in)

Returns: 0 on success, !0 on error

This ioctl attaches or detaches an ioeventfd to a legal pio/mmio address

within the guest. A guest write in the registered address will signal the

provided event instead of triggering an exit.

struct kvm_ioeventfd {

__u64 datamatch;

__u64 addr; /* legal pio/mmio address */

__u32 len; /* 1, 2, 4, or 8 bytes */

__s32 fd;

__u32 flags;

__u8 pad[36];

};

The following flags are defined:

#define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)

#define KVM_IOEVENTFD_FLAG_PIO (1 << kvm_ioeventfd_flag_nr_pio)

#define KVM_IOEVENTFD_FLAG_DEASSIGN (1 << kvm_ioeventfd_flag_nr_deassign)

If datamatch flag is set, the event will be signaled only if the written value

to the registered address is equal to datamatch in struct kvm_ioeventfd.

4.60 KVM_DIRTY_TLB

Capability: KVM_CAP_SW_TLB

Architectures: ppc

Type: vcpu ioctl

Parameters: struct kvm_dirty_tlb (in)

Returns: 0 on success, -1 on error

struct kvm_dirty_tlb {

__u64 bitmap;

__u32 num_dirty;

};

This must be called whenever userspace has changed an entry in the shared

TLB, prior to calling KVM_RUN on the associated vcpu.

The "bitmap" field is the userspace address of an array. This array

consists of a number of bits, equal to the total number of TLB entries as

determined by the last successful call to KVM_CONFIG_TLB, rounded up to the

nearest multiple of 64.

Each bit corresponds to one TLB entry, ordered the same as in the shared TLB

array.

The array is little-endian: the bit 0 is the least significant bit of the

first byte, bit 8 is the least significant bit of the second byte, etc.

This avoids any complications with differing word sizes.

The "num_dirty" field is a performance hint for KVM to determine whether it

should skip proc

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essing the bitmap and just invalidate everything. It must

be set to the number of set bits in the bitmap.

4.61 KVM_ASSIGN_SET_INTX_MASK

Capability: KVM_CAP_PCI_2_3

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_assigned_pci_dev (in)

Returns: 0 on success, -1 on error

Allows userspace to mask PCI INTx interrupts from the assigned device. The

kernel will not deliver INTx interrupts to the guest between setting and

clearing of KVM_ASSIGN_SET_INTX_MASK via this interface. This enables use of

and emulation of PCI 2.3 INTx disable command register behavior.

This may be used for both PCI 2.3 devices supporting INTx disable natively and

older devices lacking this support. Userspace is responsible for emulating the

read value of the INTx disable bit in the guest visible PCI command register.

When modifying the INTx disable state, userspace should precede updating the

physical device command register by calling this ioctl to inform the kernel of

the new intended INTx mask state.

Note that the kernel uses the device INTx disable bit to internally manage the

device interrupt state for PCI 2.3 devices. Reads of this register may

therefore not match the expected value. Writes should always use the guest

intended INTx disable value rather than attempting to read-copy-update the

current physical device state. Races between user and kernel updates to the

INTx disable bit are handled lazily in the kernel. It's possible the device

may generate unintended interrupts, but they will not be injected into the

guest.

See KVM_ASSIGN_DEV_IRQ for the data structure. The target device is specified

by assigned_dev_id. In the flags field, only KVM_DEV_ASSIGN_MASK_INTX is

evaluated.

4.62 KVM_CREATE_SPAPR_TCE

Capability: KVM_CAP_SPAPR_TCE

Architectures: powerpc

Type: vm ioctl

Parameters: struct kvm_create_spapr_tce (in)

Returns: file descriptor for manipulating the created TCE table

This creates a virtual TCE (translation control entry) table, which

is an IOMMU for PAPR-style virtual I/O. It is used to translate

logical addresses used in virtual I/O into guest physical addresses,

and provides a scatter/gather capability for PAPR virtual I/O.

/* for KVM_CAP_SPAPR_TCE */

struct kvm_create_spapr_tce {

__u64 liobn;

__u32 window_size;

};

The liobn field gives the logical IO bus number for which to create

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a

TCE table. The window_size field specifies the size of the DMA window

which this TCE table will translate - the table will contain one 64

bit TCE entry for every 4kiB of the DMA window.

When the guest issues an H_PUT_TCE hcall on a liobn for which a TCE

table has been created using this ioctl(), the kernel will handle it

in real mode, updating the TCE table. H_PUT_TCE calls for other

liobns will cause a vm exit and must be handled by userspace.

The return value is a file descriptor which can be passed to mmap(2)

to map the created TCE table into userspace. This lets userspace read

the entries written by kernel-handled H_PUT_TCE calls, and also lets

userspace update the TCE table directly which is useful in some

circumstances.

4.63 KVM_ALLOCATE_RMA

Capability: KVM_CAP_PPC_RMA

Architectures: powerpc

Type: vm ioctl

Parameters: struct kvm_allocate_rma (out)

Returns: file descriptor for mapping the allocated RMA

This allocates a Real Mode Area (RMA) from the pool allocated at boot

time by the kernel. An RMA is a physically-contiguous, aligned region

of memory used on older POWER processors to provide the memory which

will be accessed by real-mode (MMU off) accesses in a KVM guest.

POWER processors support a set of sizes for the RMA that usually

includes 64MB, 128MB, 256MB and some larger powers of two.

/* for KVM_ALLOCATE_RMA */

struct kvm_allocate_rma {

__u64 rma_size;

};

The return value is a file descriptor which can be passed to mmap(2)

to map the allocated RMA into userspace. The mapped area can then be

passed to the KVM_SET_USER_MEMORY_REGION ioctl to establish it as the

RMA for a virtual machine. The size of the RMA in bytes (which is

fixed at host kernel boot time) is returned in the rma_size field of

the argument structure.

The KVM_CAP_PPC_RMA capability is 1 or 2 if the KVM_ALLOCATE_RMA ioctl

is supported; 2 if the processor requires all virtual machines to have

an RMA, or 1 if the processor can use an RMA but doesn't require it,

because it supports the Virtual RMA (VRMA) facility.

4.64 KVM_NMI

Capability: KVM_CAP_USER_NMI

Architectures: x86

Type: vcpu ioctl

Parameters: none

Returns: 0 on success, -1 on error

Queues an NMI on the thread's vcpu. Note this is well defined only

when KVM_CREATE_IRQCHIP has not been called, since this is an interface

between the virtual cpu co

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re and virtual local APIC. After KVM_CREATE_IRQCHIP

has been called, this interface is completely emulated within the kernel.

To use this to emulate the LINT1 input with KVM_CREATE_IRQCHIP, use the

following algorithm:

- pause the vpcu

- read the local APIC's state (KVM_GET_LAPIC)

- check whether changing LINT1 will queue an NMI (see the LVT entry for LINT1)

- if so, issue KVM_NMI

- resume the vcpu

Some guests configure the LINT1 NMI input to cause a panic, aiding in

debugging.

4.65 KVM_S390_UCAS_MAP

Capability: KVM_CAP_S390_UCONTROL

Architectures: s390

Type: vcpu ioctl

Parameters: struct kvm_s390_ucas_mapping (in)

Returns: 0 in case of success

The parameter is defined like this:

struct kvm_s390_ucas_mapping {

__u64 user_addr;

__u64 vcpu_addr;

__u64 length;

};

This ioctl maps the memory at "user_addr" with the length "length" to

the vcpu's address space starting at "vcpu_addr". All parameters need to

be alligned by 1 megabyte.

4.66 KVM_S390_UCAS_UNMAP

Capability: KVM_CAP_S390_UCONTROL

Architectures: s390

Type: vcpu ioctl

Parameters: struct kvm_s390_ucas_mapping (in)

Returns: 0 in case of success

The parameter is defined like this:

struct kvm_s390_ucas_mapping {

__u64 user_addr;

__u64 vcpu_addr;

__u64 length;

};

This ioctl unmaps the memory in the vcpu's address space starting at

"vcpu_addr" with the length "length". The field "user_addr" is ignored.

All parameters need to be alligned by 1 megabyte.

4.67 KVM_S390_VCPU_FAULT

Capability: KVM_CAP_S390_UCONTROL

Architectures: s390

Type: vcpu ioctl

Parameters: vcpu absolute address (in)

Returns: 0 in case of success

This call creates a page table entry on the virtual cpu's address space

(for user controlled virtual machines) or the virtual machine's address

space (for regular virtual machines). This only works for minor faults,

thus it's recommended to access subject memory page via the user page

table upfront. This is useful to handle validity intercepts for user

controlled virtual machines to fault in the virtual cpu's lowcore pages

prior to calling the KVM_RUN ioctl.

4.68 KVM_SET_ONE_REG

Capability: KVM_CAP_ONE_REG

Architectures: all

Type: vcpu ioctl

Parameters: struct kvm_one_reg (in)

Returns: 0 on success, negative value on failure

struct kvm_one_reg {

__u64 id;

__u6

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4 addr;

};

Using this ioctl, a single vcpu register can be set to a specific value

defined by user space with the passed in struct kvm_one_reg, where id

refers to the register identifier as described below and addr is a pointer

to a variable with the respective size. There can be architecture agnostic

and architecture specific registers. Each have their own range of operation

and their own constants and width. To keep track of the implemented

registers, find a list below:

Arch | Register | Width (bits)

PPC | KVM_REG_PPC_HIOR | 64

PPC | KVM_REG_PPC_IAC1 | 64

PPC | KVM_REG_PPC_IAC2 | 64

PPC | KVM_REG_PPC_IAC3 | 64

PPC | KVM_REG_PPC_IAC4 | 64

PPC | KVM_REG_PPC_DAC1 | 64

PPC | KVM_REG_PPC_DAC2 | 64

PPC | KVM_REG_PPC_DABR | 64

PPC | KVM_REG_PPC_DSCR | 64

PPC | KVM_REG_PPC_PURR | 64

PPC | KVM_REG_PPC_SPURR | 64

PPC | KVM_REG_PPC_DAR | 64

PPC | KVM_REG_PPC_DSISR | 32

PPC | KVM_REG_PPC_AMR | 64

PPC | KVM_REG_PPC_UAMOR | 64

PPC | KVM_REG_PPC_MMCR0 | 64

PPC | KVM_REG_PPC_MMCR1 | 64

PPC | KVM_REG_PPC_MMCRA | 64

PPC | KVM_REG_PPC_PMC1 | 32

PPC | KVM_REG_PPC_PMC2 | 32

PPC | KVM_REG_PPC_PMC3 | 32

PPC | KVM_REG_PPC_PMC4 | 32

PPC | KVM_REG_PPC_PMC5 | 32

PPC | KVM_REG_PPC_PMC6 | 32

PPC | KVM_REG_PPC_PMC7 | 32

PPC | KVM_REG_PPC_PMC8 | 32

PPC | KVM_REG_PPC_FPR0 | 64

...

PPC | KVM_REG_PPC_FPR31 | 64

PPC | KVM_REG_PPC_VR0 | 128

...

PPC | KVM_REG_PPC_VR31 | 128

PPC | KVM_REG_PPC_VSR0 | 128

...

PPC | KVM_REG_PPC_VSR31 | 128

PPC | KVM_REG_PPC_FPSCR | 64

PPC | KVM_REG_PPC_VSCR | 32

PPC | KVM_REG_PPC_VPA_ADDR | 64

PPC | KVM_REG_PPC_VPA_SLB | 128

PPC | KVM_REG_PPC_VPA_DTL | 128

PPC | KVM_REG_PPC_EPCR | 32

4.69 KVM_GET_ONE_REG

Capability: KVM_CAP_ONE_REG

Architectures: all

Type: vcpu ioctl

Parameters: struct kvm_one_reg (in and out)

Returns: 0 on success, negative value on failure

This ioctl allows to receive the value of a single register implemented

in a vcpu. The register to read is indicated by the "id" field of the

kvm

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_one_reg struct passed in. On success, the register value can be found

at the memory location pointed to by "addr".

The list of registers accessible using this interface is identical to the

list in 4.68.

4.70 KVM_KVMCLOCK_CTRL

Capability: KVM_CAP_KVMCLOCK_CTRL

Architectures: Any that implement pvclocks (currently x86 only)

Type: vcpu ioctl

Parameters: None

Returns: 0 on success, -1 on error

This signals to the host kernel that the specified guest is being paused by

userspace. The host will set a flag in the pvclock structure that is checked

from the soft lockup watchdog. The flag is part of the pvclock structure that

is shared between guest and host, specifically the second bit of the flags

field of the pvclock_vcpu_time_info structure. It will be set exclusively by

the host and read/cleared exclusively by the guest. The guest operation of

checking and clearing the flag must an atomic operation so

load-link/store-conditional, or equivalent must be used. There are two cases

where the guest will clear the flag: when the soft lockup watchdog timer resets

itself or when a soft lockup is detected. This ioctl can be called any time

after pausing the vcpu, but before it is resumed.

4.71 KVM_SIGNAL_MSI

Capability: KVM_CAP_SIGNAL_MSI

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_msi (in)

Returns: >0 on delivery, 0 if guest blocked the MSI, and -1 on error

Directly inject a MSI message. Only valid with in-kernel irqchip that handles

MSI messages.

struct kvm_msi {

__u32 address_lo;

__u32 address_hi;

__u32 data;

__u32 flags;

__u8 pad[16];

};

No flags are defined so far. The corresponding field must be 0.

4.71 KVM_CREATE_PIT2

Capability: KVM_CAP_PIT2

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_pit_config (in)

Returns: 0 on success, -1 on error

Creates an in-kernel device model for the i8254 PIT. This call is only valid

after enabling in-kernel irqchip support via KVM_CREATE_IRQCHIP. The following

parameters have to be passed:

struct kvm_pit_config {

__u32 flags;

__u32 pad[15];

};

Valid flags are:

#define KVM_PIT_SPEAKER_DUMMY 1 /* emulate speaker port stub */

PIT timer interrupts may use a per-VM kernel thread for injection. If it

exists, this thread will have a name of the following pattern:

kvm-pit/

When running a

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guest with elevated priorities, the scheduling parameters of

this thread may have to be adjusted accordingly.

This IOCTL replaces the obsolete KVM_CREATE_PIT.

4.72 KVM_GET_PIT2

Capability: KVM_CAP_PIT_STATE2

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_pit_state2 (out)

Returns: 0 on success, -1 on error

Retrieves the state of the in-kernel PIT model. Only valid after

KVM_CREATE_PIT2. The state is returned in the following structure:

struct kvm_pit_state2 {

struct kvm_pit_channel_state channels[3];

__u32 flags;

__u32 reserved[9];

};

Valid flags are:

/* disable PIT in HPET legacy mode */

#define KVM_PIT_FLAGS_HPET_LEGACY 0x00000001

This IOCTL replaces the obsolete KVM_GET_PIT.

4.73 KVM_SET_PIT2

Capability: KVM_CAP_PIT_STATE2

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_pit_state2 (in)

Returns: 0 on success, -1 on error

Sets the state of the in-kernel PIT model. Only valid after KVM_CREATE_PIT2.

See KVM_GET_PIT2 for details on struct kvm_pit_state2.

This IOCTL replaces the obsolete KVM_SET_PIT.

4.74 KVM_PPC_GET_SMMU_INFO

Capability: KVM_CAP_PPC_GET_SMMU_INFO

Architectures: powerpc

Type: vm ioctl

Parameters: None

Returns: 0 on success, -1 on error

This populates and returns a structure describing the features of

the "Server" class MMU emulation supported by KVM.

This can in turn be used by userspace to generate the appropariate

device-tree properties for the guest operating system.

The structure contains some global informations, followed by an

array of supported segment page sizes:

struct kvm_ppc_smmu_info {

__u64 flags;

__u32 slb_size;

__u32 pad;

struct kvm_ppc_one_seg_page_size sps[KVM_PPC_PAGE_SIZES_MAX_SZ];

};

The supported flags are:

- KVM_PPC_PAGE_SIZES_REAL:

When that flag is set, guest page sizes must "fit" the backing

store page sizes. When not set, any page size in the list can

be used regardless of how they are backed by userspace.

- KVM_PPC_1T_SEGMENTS

The emulated MMU supports 1T segments in addition to the

standard 256M ones.

The "slb_size" field indicates how many SLB entries are supported

The "sps" array contains 8 entries indicating the supported base

page sizes for a segment in increasing order. Each entry is defined

as follow

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:

struct kvm_ppc_one_seg_page_size {

__u32 page_shift; /* Base page shift of segment (or 0) */

__u32 slb_enc; /* SLB encoding for BookS */

struct kvm_ppc_one_page_size enc[KVM_PPC_PAGE_SIZES_MAX_SZ];

};

An entry with a "page_shift" of 0 is unused. Because the array is

organized in increasing order, a lookup can stop when encoutering

such an entry.

The "slb_enc" field provides the encoding to use in the SLB for the

page size. The bits are in positions such as the value can directly

be OR'ed into the "vsid" argument of the slbmte instruction.

The "enc" array is a list which for each of those segment base page

size provides the list of supported actual page sizes (which can be

only larger or equal to the base page size), along with the

corresponding encoding in the hash PTE. Similarily, the array is

8 entries sorted by increasing sizes and an entry with a "0" shift

is an empty entry and a terminator:

struct kvm_ppc_one_page_size {

__u32 page_shift; /* Page shift (or 0) */

__u32 pte_enc; /* Encoding in the HPTE (>>12) */

};

The "pte_enc" field provides a value that can OR'ed into the hash

PTE's RPN field (ie, it needs to be shifted left by 12 to OR it

into the hash PTE second double word).

4.75 KVM_IRQFD

Capability: KVM_CAP_IRQFD

Architectures: x86

Type: vm ioctl

Parameters: struct kvm_irqfd (in)

Returns: 0 on success, -1 on error

Allows setting an eventfd to directly trigger a guest interrupt.

kvm_irqfd.fd specifies the file descriptor to use as the eventfd and

kvm_irqfd.gsi specifies the irqchip pin toggled by this event. When

an event is tiggered on the eventfd, an interrupt is injected into

the guest using the specified gsi pin. The irqfd is removed using

the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd

and kvm_irqfd.gsi.

With KVM_CAP_IRQFD_RESAMPLE, KVM_IRQFD supports a de-assert and notify

mechanism allowing emulation of level-triggered, irqfd-based

interrupts. When KVM_IRQFD_FLAG_RESAMPLE is set the user must pass an

additional eventfd in the kvm_irqfd.resamplefd field. When operating

in resample mode, posting of an interrupt through kvm_irq.fd asserts

the specified gsi in the irqchip. When the irqchip is resampled, such

as from an EOI, the gsi is de-asserted and the user is notifed via

kvm_irqfd.resamplefd. It is the user's responsibility to re-queue

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the interrupt if the device making use of it still requires service.

Note that closing the resamplefd is not sufficient to disable the

irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment

and need not be specified with KVM_IRQFD_FLAG_DEASSIGN.

4.76 KVM_PPC_ALLOCATE_HTAB

Capability: KVM_CAP_PPC_ALLOC_HTAB

Architectures: powerpc

Type: vm ioctl

Parameters: Pointer to u32 containing hash table order (in/out)

Returns: 0 on success, -1 on error

This requests the host kernel to allocate an MMU hash table for a

guest using the PAPR paravirtualization interface. This only does

anything if the kernel is configured to use the Book 3S HV style of

virtualization. Otherwise the capability doesn't exist and the ioctl

returns an ENOTTY error. The rest of this description assumes Book 3S

HV.

There must be no vcpus running when this ioctl is called; if there

are, it will do nothing and return an EBUSY error.

The parameter is a pointer to a 32-bit unsigned integer variable

containing the order (log base 2) of the desired size of the hash

table, which must be between 18 and 46. On successful return from the

ioctl, it will have been updated with the order of the hash table that

was allocated.

If no hash table has been allocated when any vcpu is asked to run

(with the KVM_RUN ioctl), the host kernel will allocate a

default-sized hash table (16 MB).

If this ioctl is called when a hash table has already been allocated,

the kernel will clear out the existing hash table (zero all HPTEs) and

return the hash table order in the parameter. (If the guest is using

the virtualized real-mode area (VRMA) facility, the kernel will

re-create the VMRA HPTEs on the next KVM_RUN of any vcpu.)

4.77 KVM_S390_INTERRUPT

Capability: basic

Architectures: s390

Type: vm ioctl, vcpu ioctl

Parameters: struct kvm_s390_interrupt (in)

Returns: 0 on success, -1 on error

Allows to inject an interrupt to the guest. Interrupts can be floating

(vm ioctl) or per cpu (vcpu ioctl), depending on the interrupt type.

Interrupt parameters are passed via kvm_s390_interrupt:

struct kvm_s390_interrupt {

__u32 type;

__u32 parm;

__u64 parm64;

};

type can be one of the following:

KVM_S390_SIGP_STOP (vcpu) - sigp restart

KVM_S390_PROGRAM_INT (vcpu) - program check; code in parm

KVM_S390_SIGP_SET_PREFIX (vcpu) - sigp set prefix; pre

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fix address in parm

KVM_S390_RESTART (vcpu) - restart

KVM_S390_INT_VIRTIO (vm) - virtio external interrupt; external interrupt

parameters in parm and parm64

KVM_S390_INT_SERVICE (vm) - sclp external interrupt; sclp parameter in parm

KVM_S390_INT_EMERGENCY (vcpu) - sigp emergency; source cpu in parm

KVM_S390_INT_EXTERNAL_CALL (vcpu) - sigp external call; source cpu in parm

Note that the vcpu ioctl is asynchronous to vcpu execution.

4.78 KVM_PPC_GET_HTAB_FD

Capability: KVM_CAP_PPC_HTAB_FD

Architectures: powerpc

Type: vm ioctl

Parameters: Pointer to struct kvm_get_htab_fd (in)

Returns: file descriptor number (>= 0) on success, -1 on error

This returns a file descriptor that can be used either to read out the

entries in the guest's hashed page table (HPT), or to write entries to

initialize the HPT. The returned fd can only be written to if the

KVM_GET_HTAB_WRITE bit is set in the flags field of the argument, and

can only be read if that bit is clear. The argument struct looks like

this:

/* For KVM_PPC_GET_HTAB_FD */

struct kvm_get_htab_fd {

__u64 flags;

__u64 start_index;

__u64 reserved[2];

};

/* Values for kvm_get_htab_fd.flags */

#define KVM_GET_HTAB_BOLTED_ONLY ((__u64)0x1)

#define KVM_GET_HTAB_WRITE ((__u64)0x2)

The `start_index' field gives the index in the HPT of the entry at

which to start reading. It is ignored when writing.

Reads on the fd will initially supply information about all

"interesting" HPT entries. Interesting entries are those with the

bolted bit set, if the KVM_GET_HTAB_BOLTED_ONLY bit is set, otherwise

all entries. When the end of the HPT is reached, the read() will

return. If read() is called again on the fd, it will start again from

the beginning of the HPT, but will only return HPT entries that have

changed since they were last read.

Data read or written is structured as a header (8 bytes) followed by a

series of valid HPT entries (16 bytes) each. The header indicates how

many valid HPT entries there are and how many invalid entries follow

the valid entries. The invalid entries are not represented explicitly

in the stream. The header format is:

struct kvm_get_htab_header {

__u32 index;

__u16 n_valid;

__u16 n_invalid;

};

Writes to the fd create HPT entries starting at the index given in the

header; first `n_valid' valid entries with contents from

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the data

written, then `n_invalid' invalid entries, invalidating any previously

valid entries found.

5. The kvm_run structure

------------------------

Application code obtains a pointer to the kvm_run structure by

mmap()ing a vcpu fd. From that point, application code can control

execution by changing fields in kvm_run prior to calling the KVM_RUN

ioctl, and obtain information about the reason KVM_RUN returned by

looking up structure members.

struct kvm_run {

/* in */

__u8 request_interrupt_window;

Request that KVM_RUN return when it becomes possible to inject external

interrupts into the guest. Useful in conjunction with KVM_INTERRUPT.

__u8 padding1[7];

/* out */

__u32 exit_reason;

When KVM_RUN has returned successfully (return value 0), this informs

application code why KVM_RUN has returned. Allowable values for this

field are detailed below.

__u8 ready_for_interrupt_injection;

If request_interrupt_window has been specified, this field indicates

an interrupt can be injected now with KVM_INTERRUPT.

__u8 if_flag;

The value of the current interrupt flag. Only valid if in-kernel

local APIC is not used.

__u8 padding2[2];

/* in (pre_kvm_run), out (post_kvm_run) */

__u64 cr8;

The value of the cr8 register. Only valid if in-kernel local APIC is

not used. Both input and output.

__u64 apic_base;

The value of the APIC BASE msr. Only valid if in-kernel local

APIC is not used. Both input and output.

union {

/* KVM_EXIT_UNKNOWN */

struct {

__u64 hardware_exit_reason;

} hw;

If exit_reason is KVM_EXIT_UNKNOWN, the vcpu has exited due to unknown

reasons. Further architecture-specific information is available in

hardware_exit_reason.

/* KVM_EXIT_FAIL_ENTRY */

struct {

__u64 hardware_entry_failure_reason;

} fail_entry;

If exit_reason is KVM_EXIT_FAIL_ENTRY, the vcpu could not be run due

to unknown reasons. Further architecture-specific information is

available in hardware_entry_failure_reason.

/* KVM_EXIT_EXCEPTION */

struct {

__u32 exception;

__u32 error_code;

} ex;

Unused.

/* KVM_EXIT_IO */

struct {

#define KVM_EXIT_IO_IN 0

#define KVM_EXIT_IO_OUT 1

__u8 direction;

__u8 size; /* bytes */

__u16 port;

__u32 count;

__u64 data_offset; /* relative to kvm_run start */

} io;

If exit_reason is

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KVM_EXIT_IO, then the vcpu has

executed a port I/O instruction which could not be satisfied by kvm.

data_offset describes where the data is located (KVM_EXIT_IO_OUT) or

where kvm expects application code to place the data for the next

KVM_RUN invocation (KVM_EXIT_IO_IN). Data format is a packed array.

struct {

struct kvm_debug_exit_arch arch;

} debug;

Unused.

/* KVM_EXIT_MMIO */

struct {

__u64 phys_addr;

__u8 data[8];

__u32 len;

__u8 is_write;

} mmio;

If exit_reason is KVM_EXIT_MMIO, then the vcpu has

executed a memory-mapped I/O instruction which could not be satisfied

by kvm. The 'data' member contains the written data if 'is_write' is

true, and should be filled by application code otherwise.

NOTE: For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_DCR

and KVM_EXIT_PAPR the corresponding

operations are complete (and guest state is consistent) only after userspace

has re-entered the kernel with KVM_RUN. The kernel side will first finish

incomplete operations and then check for pending signals. Userspace

can re-enter the guest with an unmasked signal pending to complete

pending operations.

/* KVM_EXIT_HYPERCALL */

struct {

__u64 nr;

__u64 args[6];

__u64 ret;

__u32 longmode;

__u32 pad;

} hypercall;

Unused. This was once used for 'hypercall to userspace'. To implement

such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).

Note KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO.

/* KVM_EXIT_TPR_ACCESS */

struct {

__u64 rip;

__u32 is_write;

__u32 pad;

} tpr_access;

To be documented (KVM_TPR_ACCESS_REPORTING).

/* KVM_EXIT_S390_SIEIC */

struct {

__u8 icptcode;

__u64 mask; /* psw upper half */

__u64 addr; /* psw lower half */

__u16 ipa;

__u32 ipb;

} s390_sieic;

s390 specific.

/* KVM_EXIT_S390_RESET */

#define KVM_S390_RESET_POR 1

#define KVM_S390_RESET_CLEAR 2

#define KVM_S390_RESET_SUBSYSTEM 4

#define KVM_S390_RESET_CPU_INIT 8

#define KVM_S390_RESET_IPL 16

__u64 s390_reset_flags;

s390 specific.

/* KVM_EXIT_S390_UCONTROL */

struct {

__u64 trans_exc_code;

__u32 pgm_code;

} s390_ucontrol;

s390 specific. A page fault has occurred for a user controlled virtual

machine (KVM_VM_S390_UNCONTROL) on it's host page table

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that cannot be

resolved by the kernel.

The program code and the translation exception code that were placed

in the cpu's lowcore are presented here as defined by the z Architecture

Principles of Operation Book in the Chapter for Dynamic Address Translation

(DAT)

/* KVM_EXIT_DCR */

struct {

__u32 dcrn;

__u32 data;

__u8 is_write;

} dcr;

powerpc specific.

/* KVM_EXIT_OSI */

struct {

__u64 gprs[32];

} osi;

MOL uses a special hypercall interface it calls 'OSI'. To enable it, we catch

hypercalls and exit with this exit struct that contains all the guest gprs.

If exit_reason is KVM_EXIT_OSI, then the vcpu has triggered such a hypercall.

Userspace can now handle the hypercall and when it's done modify the gprs as

necessary. Upon guest entry all guest GPRs will then be replaced by the values

in this struct.

/* KVM_EXIT_PAPR_HCALL */

struct {

__u64 nr;

__u64 ret;

__u64 args[9];

} papr_hcall;

This is used on 64-bit PowerPC when emulating a pSeries partition,

e.g. with the 'pseries' machine type in qemu. It occurs when the

guest does a hypercall using the 'sc 1' instruction. The 'nr' field

contains the hypercall number (from the guest R3), and 'args' contains

the arguments (from the guest R4 - R12). Userspace should put the

return code in 'ret' and any extra returned values in args[].

The possible hypercalls are defined in the Power Architecture Platform

Requirements (PAPR) document available from www.power.org (free

developer registration required to access it).

/* Fix the size of the union. */

char padding[256];

};

/*

* shared registers between kvm and userspace.

* kvm_valid_regs specifies the register classes set by the host

* kvm_dirty_regs specified the register classes dirtied by userspace

* struct kvm_sync_regs is architecture specific, as well as the

* bits for kvm_valid_regs and kvm_dirty_regs

*/

__u64 kvm_valid_regs;

__u64 kvm_dirty_regs;

union {

struct kvm_sync_regs regs;

char padding[1024];

} s;

If KVM_CAP_SYNC_REGS is defined, these fields allow userspace to access

certain guest registers without having to call SET/GET_*REGS. Thus we can

avoid some system call overhead if userspace has to handle the exit.

Userspace can query the validity of the structure by checking

kvm_valid_regs for specific bits. These bits a

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re architecture specific

and usually define the validity of a groups of registers. (e.g. one bit

for general purpose registers)

};

6. Capabilities that can be enabled

-----------------------------------

There are certain capabilities that change the behavior of the virtual CPU when

enabled. To enable them, please see section 4.37. Below you can find a list of

capabilities and what their effect on the vCPU is when enabling them.

The following information is provided along with the description:

Architectures: which instruction set architectures provide this ioctl.

x86 includes both i386 and x86_64.

Parameters: what parameters are accepted by the capability.

Returns: the return value. General error numbers (EBADF, ENOMEM, EINVAL)

are not detailed, but errors with specific meanings are.

6.1 KVM_CAP_PPC_OSI

Architectures: ppc

Parameters: none

Returns: 0 on success; -1 on error

This capability enables interception of OSI hypercalls that otherwise would

be treated as normal system calls to be injected into the guest. OSI hypercalls

were invented by Mac-on-Linux to have a standardized communication mechanism

between the guest and the host.

When this capability is enabled, KVM_EXIT_OSI can occur.

6.2 KVM_CAP_PPC_PAPR

Architectures: ppc

Parameters: none

Returns: 0 on success; -1 on error

This capability enables interception of PAPR hypercalls. PAPR hypercalls are

done using the hypercall instruction "sc 1".

It also sets the guest privilege level to "supervisor" mode. Usually the guest

runs in "hypervisor" privilege mode with a few missing features.

In addition to the above, it changes the semantics of SDR1. In this mode, the

HTAB address part of SDR1 contains an HVA instead of a GPA, as PAPR keeps the

HTAB invisible to the guest.

When this capability is enabled, KVM_EXIT_PAPR_HCALL can occur.

6.3 KVM_CAP_SW_TLB

Architectures: ppc

Parameters: args[0] is the address of a struct kvm_config_tlb

Returns: 0 on success; -1 on error

struct kvm_config_tlb {

__u64 params;

__u64 array;

__u32 mmu_type;

__u32 array_len;

};

Configures the virtual CPU's TLB array, establishing a shared memory area

between userspace and KVM. The "params" and "array" fields are userspace

addresses of mmu-type-specific data structures. The "array_len" field is an

safety mechanism

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, and should be set to the size in bytes of the memory that

userspace has reserved for the array. It must be at least the size dictated

by "mmu_type" and "params".

While KVM_RUN is active, the shared region is under control of KVM. Its

contents are undefined, and any modification by userspace results in

boundedly undefined behavior.

On return from KVM_RUN, the shared region will reflect the current state of

the guest's TLB. If userspace makes any changes, it must call KVM_DIRTY_TLB

to tell KVM which entries have been changed, prior to calling KVM_RUN again

on this vcpu.

For mmu types KVM_MMU_FSL_BOOKE_NOHV and KVM_MMU_FSL_BOOKE_HV:

- The "params" field is of type "struct kvm_book3e_206_tlb_params".

- The "array" field points to an array of type "struct

kvm_book3e_206_tlb_entry".

- The array consists of all entries in the first TLB, followed by all

entries in the second TLB.

- Within a TLB, entries are ordered first by increasing set number. Within a

set, entries are ordered by way (increasing ESEL).

- The hash for determining set number in TLB0 is: (MAS2 >> 12) & (num_sets - 1)

where "num_sets" is the tlb_sizes[] value divided by the tlb_ways[] value.

- The tsize field of mas1 shall be set to 4K on TLB0, even though the

hardware ignores this value for TLB0.

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