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KVM: Improve readability of KVM API doc

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This helps to identify sections and it also fixes the numbering from
4.54 to 4.61.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Jan Kiszka 2012-04-24 16:40:15 +02:00 committed by Marcelo Tosatti
parent 38e8a2ddc9
commit 414fa985f9
1 changed files with 92 additions and 7 deletions
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99
Documentation/virtual/kvm/api.txt
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@ -2,6 +2,7 @@ The Definitive KVM (Kernel-based Virtual Machine) API Documentation
===================================================================
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
@ -23,7 +24,9 @@ of a virtual machine. The ioctls belong to three classes
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
@ -41,7 +44,9 @@ 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
@ -53,7 +58,9 @@ Instead, kvm defines extension identifiers and a facility to query
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
@ -75,6 +82,7 @@ description:
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
@ -90,6 +98,7 @@ 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
@ -109,6 +118,7 @@ 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
@ -135,6 +145,7 @@ 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
@ -149,6 +160,7 @@ 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
@ -161,6 +173,7 @@ 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
@ -171,6 +184,7 @@ Returns: 0 on success, -1 on error
This ioctl is obsolete and has been removed.
4.7 KVM_CREATE_VCPU
Capability: basic
@ -223,6 +237,7 @@ 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
@ -246,6 +261,7 @@ 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
@ -256,6 +272,7 @@ Returns: 0 (success), -1 (error)
This ioctl is obsolete and has been removed.
4.10 KVM_RUN
Capability: basic
@ -272,6 +289,7 @@ 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
@ -292,6 +310,7 @@ struct kvm_regs {
__u64 rip, rflags;
};
4.12 KVM_SET_REGS
Capability: basic
@ -304,6 +323,7 @@ Writes the general purpose registers into the vcpu.
See KVM_GET_REGS for the data structure.
4.13 KVM_GET_SREGS
Capability: basic
@ -331,6 +351,7 @@ 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
@ -342,6 +363,7 @@ Returns: 0 on success, -1 on error
Writes special registers into the vcpu. See KVM_GET_SREGS for the
data structures.
4.15 KVM_TRANSLATE
Capability: basic
@ -365,6 +387,7 @@ struct kvm_translation {
__u8 pad[5];
};
4.16 KVM_INTERRUPT
Capability: basic
@ -413,6 +436,7 @@ c) KVM_INTERRUPT_SET_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
@ -423,6 +447,7 @@ Returns: -1 on error
Support for this has been removed. Use KVM_SET_GUEST_DEBUG instead.
4.18 KVM_GET_MSRS
Capability: basic
@ -451,6 +476,7 @@ Application 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
@ -466,6 +492,7 @@ 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
@ -494,6 +521,7 @@ struct kvm_cpuid {
struct kvm_cpuid_entry entries[0];
};
4.21 KVM_SET_SIGNAL_MASK
Capability: basic
@ -516,6 +544,7 @@ struct kvm_signal_mask {
__u8 sigset[0];
};
4.22 KVM_GET_FPU
Capability: basic
@ -541,6 +570,7 @@ struct kvm_fpu {
__u32 pad2;
};
4.23 KVM_SET_FPU
Capability: basic
@ -566,6 +596,7 @@ struct kvm_fpu {
__u32 pad2;
};
4.24 KVM_CREATE_IRQCHIP
Capability: KVM_CAP_IRQCHIP
@ -579,6 +610,7 @@ 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
@ -600,6 +632,7 @@ struct kvm_irq_level {
__u32 level; /* 0 or 1 */
};
4.26 KVM_GET_IRQCHIP
Capability: KVM_CAP_IRQCHIP
@ -621,6 +654,7 @@ struct kvm_irqchip {
} chip;
};
4.27 KVM_SET_IRQCHIP
Capability: KVM_CAP_IRQCHIP
@ -642,6 +676,7 @@ struct kvm_irqchip {
} chip;
};
4.28 KVM_XEN_HVM_CONFIG
Capability: KVM_CAP_XEN_HVM
@ -666,6 +701,7 @@ struct kvm_xen_hvm_config {
__u8 pad2[30];
};
4.29 KVM_GET_CLOCK
Capability: KVM_CAP_ADJUST_CLOCK
@ -684,6 +720,7 @@ struct kvm_clock_data {
__u32 pad[9];
};
4.30 KVM_SET_CLOCK
Capability: KVM_CAP_ADJUST_CLOCK
@ -702,6 +739,7 @@ struct kvm_clock_data {
__u32 pad[9];
};
4.31 KVM_GET_VCPU_EVENTS
Capability: KVM_CAP_VCPU_EVENTS
@ -741,6 +779,7 @@ struct kvm_vcpu_events {
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
@ -767,6 +806,7 @@ 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
@ -785,6 +825,7 @@ struct kvm_debugregs {
__u64 reserved[9];
};
4.34 KVM_SET_DEBUGREGS
Capability: KVM_CAP_DEBUGREGS
@ -798,6 +839,7 @@ 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
@ -844,6 +886,7 @@ 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
@ -862,6 +905,7 @@ 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
@ -897,6 +941,7 @@ function properly, this is the place to put them.
__u8 pad[64];
};
4.38 KVM_GET_MP_STATE
Capability: KVM_CAP_MP_STATE
@ -927,6 +972,7 @@ Possible values are:
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
@ -941,6 +987,7 @@ 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
@ -959,6 +1006,7 @@ 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
@ -971,6 +1019,7 @@ 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
@ -985,6 +1034,7 @@ struct kvm_xsave {
This ioctl would copy current vcpu's xsave struct to the userspace.
4.43 KVM_SET_XSAVE
Capability: KVM_CAP_XSAVE
@ -999,6 +1049,7 @@ struct kvm_xsave {
This ioctl would copy userspace's xsave struct to the kernel.
4.44 KVM_GET_XCRS
Capability: KVM_CAP_XCRS
@ -1022,6 +1073,7 @@ struct kvm_xcrs {
This ioctl would copy current vcpu's xcrs to the userspace.
4.45 KVM_SET_XCRS
Capability: KVM_CAP_XCRS
@ -1045,6 +1097,7 @@ struct kvm_xcrs {
This ioctl would set vcpu's xcr to the value userspace specified.
4.46 KVM_GET_SUPPORTED_CPUID
Capability: KVM_CAP_EXT_CPUID
@ -1119,6 +1172,7 @@ support. Instead it is reported via
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
@ -1142,6 +1196,7 @@ of 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.
4.48 KVM_ASSIGN_PCI_DEVICE
Capability: KVM_CAP_DEVICE_ASSIGNMENT
@ -1185,6 +1240,7 @@ 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 with the device.
4.49 KVM_DEASSIGN_PCI_DEVICE
Capability: KVM_CAP_DEVICE_DEASSIGNMENT
@ -1198,6 +1254,7 @@ 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
@ -1231,6 +1288,7 @@ The following flags are defined:
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
@ -1245,6 +1303,7 @@ 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
@ -1293,6 +1352,7 @@ struct kvm_irq_routing_msi {
__u32 pad;
};
4.53 KVM_ASSIGN_SET_MSIX_NR
Capability: KVM_CAP_DEVICE_MSIX
@ -1314,6 +1374,7 @@ struct kvm_assigned_msix_nr {
#define KVM_MAX_MSIX_PER_DEV 256
4.54 KVM_ASSIGN_SET_MSIX_ENTRY
Capability: KVM_CAP_DEVICE_MSIX
@ -1332,7 +1393,8 @@ struct kvm_assigned_msix_entry {
__u16 padding[3];
};
4.54 KVM_SET_TSC_KHZ
4.55 KVM_SET_TSC_KHZ
Capability: KVM_CAP_TSC_CONTROL
Architectures: x86
@ -1343,7 +1405,8 @@ Returns: 0 on success, -1 on error
Specifies the tsc frequency for the virtual machine. The unit of the
frequency is KHz.
4.55 KVM_GET_TSC_KHZ
4.56 KVM_GET_TSC_KHZ
Capability: KVM_CAP_GET_TSC_KHZ
Architectures: x86
@ -1355,7 +1418,8 @@ 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.
4.56 KVM_GET_LAPIC
4.57 KVM_GET_LAPIC
Capability: KVM_CAP_IRQCHIP
Architectures: x86
@ -1371,7 +1435,8 @@ struct kvm_lapic_state {
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.
4.57 KVM_SET_LAPIC
4.58 KVM_SET_LAPIC
Capability: KVM_CAP_IRQCHIP
Architectures: x86
@ -1387,7 +1452,8 @@ struct kvm_lapic_state {
Copies the input argument into the the Local APIC registers. The data format
and layout are the same as documented in the architecture manual.
4.58 KVM_IOEVENTFD
4.59 KVM_IOEVENTFD
Capability: KVM_CAP_IOEVENTFD
Architectures: all
@ -1417,7 +1483,8 @@ The following flags are defined:
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.
4.59 KVM_DIRTY_TLB
4.60 KVM_DIRTY_TLB
Capability: KVM_CAP_SW_TLB
Architectures: ppc
@ -1449,7 +1516,8 @@ The "num_dirty" field is a performance hint for KVM to determine whether it
should skip processing the bitmap and just invalidate everything. It must
be set to the number of set bits in the bitmap.
4.60 KVM_ASSIGN_SET_INTX_MASK
4.61 KVM_ASSIGN_SET_INTX_MASK
Capability: KVM_CAP_PCI_2_3
Architectures: x86
@ -1482,6 +1550,7 @@ 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
@ -1517,6 +1586,7 @@ 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
@ -1549,6 +1619,7 @@ 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
@ -1574,6 +1645,7 @@ following algorithm:
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
@ -1593,6 +1665,7 @@ 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
@ -1612,6 +1685,7 @@ 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
@ -1628,6 +1702,7 @@ 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
@ -1653,6 +1728,7 @@ registers, find a list below:
| |
PPC | KVM_REG_PPC_HIOR | 64
4.69 KVM_GET_ONE_REG
Capability: KVM_CAP_ONE_REG
@ -1669,6 +1745,7 @@ at the memory location pointed to by "addr".
The list of registers accessible using this interface is identical to the
list in 4.64.
4.70 KVM_KVMCLOCK_CTRL
Capability: KVM_CAP_KVMCLOCK_CTRL
@ -1689,6 +1766,7 @@ 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
@ -1710,7 +1788,9 @@ struct kvm_msi {
No flags are defined so far. The corresponding field must be 0.
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
@ -1951,7 +2031,9 @@ and usually define the validity of a groups of registers. (e.g. one bit
};
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
@ -1967,6 +2049,7 @@ The following information is provided along with the description:
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
@ -1980,6 +2063,7 @@ between the guest and the host.
When this capability is enabled, KVM_EXIT_OSI can occur.
6.2 KVM_CAP_PPC_PAPR
Architectures: ppc
@ -1998,6 +2082,7 @@ HTAB invisible to the guest.
When this capability is enabled, KVM_EXIT_PAPR_HCALL can occur.
6.3 KVM_CAP_SW_TLB
Architectures: ppc