KVM: Improve readability of KVM API doc

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>

Documentation/virtual/kvm/api.txt

@@ -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