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authorLinus Torvalds <torvalds@linux-foundation.org>2018-02-10 13:16:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-10 13:16:35 -0800
commit15303ba5d1cd9b28d03a980456c0978c0ea3b208 (patch)
treeb9200d5b7474661cf36468038529a5269ee83238 /Documentation
parent9a61df9e5f7471fe5be3e02bd0bed726b2761a54 (diff)
parent1ab03c072feb579c9fd116de25be2b211e6bff6a (diff)
downloadlinux-15303ba5d1cd9b28d03a980456c0978c0ea3b208.tar.bz2
Merge tag 'kvm-4.16-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Radim Krčmář: "ARM: - icache invalidation optimizations, improving VM startup time - support for forwarded level-triggered interrupts, improving performance for timers and passthrough platform devices - a small fix for power-management notifiers, and some cosmetic changes PPC: - add MMIO emulation for vector loads and stores - allow HPT guests to run on a radix host on POWER9 v2.2 CPUs without requiring the complex thread synchronization of older CPU versions - improve the handling of escalation interrupts with the XIVE interrupt controller - support decrement register migration - various cleanups and bugfixes. s390: - Cornelia Huck passed maintainership to Janosch Frank - exitless interrupts for emulated devices - cleanup of cpuflag handling - kvm_stat counter improvements - VSIE improvements - mm cleanup x86: - hypervisor part of SEV - UMIP, RDPID, and MSR_SMI_COUNT emulation - paravirtualized TLB shootdown using the new KVM_VCPU_PREEMPTED bit - allow guests to see TOPOEXT, GFNI, VAES, VPCLMULQDQ, and more AVX512 features - show vcpu id in its anonymous inode name - many fixes and cleanups - per-VCPU MSR bitmaps (already merged through x86/pti branch) - stable KVM clock when nesting on Hyper-V (merged through x86/hyperv)" * tag 'kvm-4.16-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (197 commits) KVM: PPC: Book3S: Add MMIO emulation for VMX instructions KVM: PPC: Book3S HV: Branch inside feature section KVM: PPC: Book3S HV: Make HPT resizing work on POWER9 KVM: PPC: Book3S HV: Fix handling of secondary HPTEG in HPT resizing code KVM: PPC: Book3S PR: Fix broken select due to misspelling KVM: x86: don't forget vcpu_put() in kvm_arch_vcpu_ioctl_set_sregs() KVM: PPC: Book3S PR: Fix svcpu copying with preemption enabled KVM: PPC: Book3S HV: Drop locks before reading guest memory kvm: x86: remove efer_reload entry in kvm_vcpu_stat KVM: x86: AMD Processor Topology Information x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO when running nested kvm: embed vcpu id to dentry of vcpu anon inode kvm: Map PFN-type memory regions as writable (if possible) x86/kvm: Make it compile on 32bit and with HYPYERVISOR_GUEST=n KVM: arm/arm64: Fixup userspace irqchip static key optimization KVM: arm/arm64: Fix userspace_irqchip_in_use counting KVM: arm/arm64: Fix incorrect timer_is_pending logic MAINTAINERS: update KVM/s390 maintainers MAINTAINERS: add Halil as additional vfio-ccw maintainer MAINTAINERS: add David as a reviewer for KVM/s390 ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/virtual/kvm/00-INDEX3
-rw-r--r--Documentation/virtual/kvm/amd-memory-encryption.rst247
-rw-r--r--Documentation/virtual/kvm/api.txt54
-rw-r--r--Documentation/virtual/kvm/arm/vgic-mapped-irqs.txt187
-rw-r--r--Documentation/virtual/kvm/cpuid.txt4
5 files changed, 307 insertions, 188 deletions
diff --git a/Documentation/virtual/kvm/00-INDEX b/Documentation/virtual/kvm/00-INDEX
index 69fe1a8b7ad1..3da73aabff5a 100644
--- a/Documentation/virtual/kvm/00-INDEX
+++ b/Documentation/virtual/kvm/00-INDEX
@@ -26,3 +26,6 @@ s390-diag.txt
- Diagnose hypercall description (for IBM S/390)
timekeeping.txt
- timekeeping virtualization for x86-based architectures.
+amd-memory-encryption.txt
+ - notes on AMD Secure Encrypted Virtualization feature and SEV firmware
+ command description
diff --git a/Documentation/virtual/kvm/amd-memory-encryption.rst b/Documentation/virtual/kvm/amd-memory-encryption.rst
new file mode 100644
index 000000000000..71d6d257074f
--- /dev/null
+++ b/Documentation/virtual/kvm/amd-memory-encryption.rst
@@ -0,0 +1,247 @@
+======================================
+Secure Encrypted Virtualization (SEV)
+======================================
+
+Overview
+========
+
+Secure Encrypted Virtualization (SEV) is a feature found on AMD processors.
+
+SEV is an extension to the AMD-V architecture which supports running
+virtual machines (VMs) under the control of a hypervisor. When enabled,
+the memory contents of a VM will be transparently encrypted with a key
+unique to that VM.
+
+The hypervisor can determine the SEV support through the CPUID
+instruction. The CPUID function 0x8000001f reports information related
+to SEV::
+
+ 0x8000001f[eax]:
+ Bit[1] indicates support for SEV
+ ...
+ [ecx]:
+ Bits[31:0] Number of encrypted guests supported simultaneously
+
+If support for SEV is present, MSR 0xc001_0010 (MSR_K8_SYSCFG) and MSR 0xc001_0015
+(MSR_K7_HWCR) can be used to determine if it can be enabled::
+
+ 0xc001_0010:
+ Bit[23] 1 = memory encryption can be enabled
+ 0 = memory encryption can not be enabled
+
+ 0xc001_0015:
+ Bit[0] 1 = memory encryption can be enabled
+ 0 = memory encryption can not be enabled
+
+When SEV support is available, it can be enabled in a specific VM by
+setting the SEV bit before executing VMRUN.::
+
+ VMCB[0x90]:
+ Bit[1] 1 = SEV is enabled
+ 0 = SEV is disabled
+
+SEV hardware uses ASIDs to associate a memory encryption key with a VM.
+Hence, the ASID for the SEV-enabled guests must be from 1 to a maximum value
+defined in the CPUID 0x8000001f[ecx] field.
+
+SEV Key Management
+==================
+
+The SEV guest key management is handled by a separate processor called the AMD
+Secure Processor (AMD-SP). Firmware running inside the AMD-SP provides a secure
+key management interface to perform common hypervisor activities such as
+encrypting bootstrap code, snapshot, migrating and debugging the guest. For more
+information, see the SEV Key Management spec [api-spec]_
+
+KVM implements the following commands to support common lifecycle events of SEV
+guests, such as launching, running, snapshotting, migrating and decommissioning.
+
+1. KVM_SEV_INIT
+---------------
+
+The KVM_SEV_INIT command is used by the hypervisor to initialize the SEV platform
+context. In a typical workflow, this command should be the first command issued.
+
+Returns: 0 on success, -negative on error
+
+2. KVM_SEV_LAUNCH_START
+-----------------------
+
+The KVM_SEV_LAUNCH_START command is used for creating the memory encryption
+context. To create the encryption context, user must provide a guest policy,
+the owner's public Diffie-Hellman (PDH) key and session information.
+
+Parameters: struct kvm_sev_launch_start (in/out)
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_launch_start {
+ __u32 handle; /* if zero then firmware creates a new handle */
+ __u32 policy; /* guest's policy */
+
+ __u64 dh_uaddr; /* userspace address pointing to the guest owner's PDH key */
+ __u32 dh_len;
+
+ __u64 session_addr; /* userspace address which points to the guest session information */
+ __u32 session_len;
+ };
+
+On success, the 'handle' field contains a new handle and on error, a negative value.
+
+For more details, see SEV spec Section 6.2.
+
+3. KVM_SEV_LAUNCH_UPDATE_DATA
+-----------------------------
+
+The KVM_SEV_LAUNCH_UPDATE_DATA is used for encrypting a memory region. It also
+calculates a measurement of the memory contents. The measurement is a signature
+of the memory contents that can be sent to the guest owner as an attestation
+that the memory was encrypted correctly by the firmware.
+
+Parameters (in): struct kvm_sev_launch_update_data
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_launch_update {
+ __u64 uaddr; /* userspace address to be encrypted (must be 16-byte aligned) */
+ __u32 len; /* length of the data to be encrypted (must be 16-byte aligned) */
+ };
+
+For more details, see SEV spec Section 6.3.
+
+4. KVM_SEV_LAUNCH_MEASURE
+-------------------------
+
+The KVM_SEV_LAUNCH_MEASURE command is used to retrieve the measurement of the
+data encrypted by the KVM_SEV_LAUNCH_UPDATE_DATA command. The guest owner may
+wait to provide the guest with confidential information until it can verify the
+measurement. Since the guest owner knows the initial contents of the guest at
+boot, the measurement can be verified by comparing it to what the guest owner
+expects.
+
+Parameters (in): struct kvm_sev_launch_measure
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_launch_measure {
+ __u64 uaddr; /* where to copy the measurement */
+ __u32 len; /* length of measurement blob */
+ };
+
+For more details on the measurement verification flow, see SEV spec Section 6.4.
+
+5. KVM_SEV_LAUNCH_FINISH
+------------------------
+
+After completion of the launch flow, the KVM_SEV_LAUNCH_FINISH command can be
+issued to make the guest ready for the execution.
+
+Returns: 0 on success, -negative on error
+
+6. KVM_SEV_GUEST_STATUS
+-----------------------
+
+The KVM_SEV_GUEST_STATUS command is used to retrieve status information about a
+SEV-enabled guest.
+
+Parameters (out): struct kvm_sev_guest_status
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_guest_status {
+ __u32 handle; /* guest handle */
+ __u32 policy; /* guest policy */
+ __u8 state; /* guest state (see enum below) */
+ };
+
+SEV guest state:
+
+::
+
+ enum {
+ SEV_STATE_INVALID = 0;
+ SEV_STATE_LAUNCHING, /* guest is currently being launched */
+ SEV_STATE_SECRET, /* guest is being launched and ready to accept the ciphertext data */
+ SEV_STATE_RUNNING, /* guest is fully launched and running */
+ SEV_STATE_RECEIVING, /* guest is being migrated in from another SEV machine */
+ SEV_STATE_SENDING /* guest is getting migrated out to another SEV machine */
+ };
+
+7. KVM_SEV_DBG_DECRYPT
+----------------------
+
+The KVM_SEV_DEBUG_DECRYPT command can be used by the hypervisor to request the
+firmware to decrypt the data at the given memory region.
+
+Parameters (in): struct kvm_sev_dbg
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_dbg {
+ __u64 src_uaddr; /* userspace address of data to decrypt */
+ __u64 dst_uaddr; /* userspace address of destination */
+ __u32 len; /* length of memory region to decrypt */
+ };
+
+The command returns an error if the guest policy does not allow debugging.
+
+8. KVM_SEV_DBG_ENCRYPT
+----------------------
+
+The KVM_SEV_DEBUG_ENCRYPT command can be used by the hypervisor to request the
+firmware to encrypt the data at the given memory region.
+
+Parameters (in): struct kvm_sev_dbg
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_dbg {
+ __u64 src_uaddr; /* userspace address of data to encrypt */
+ __u64 dst_uaddr; /* userspace address of destination */
+ __u32 len; /* length of memory region to encrypt */
+ };
+
+The command returns an error if the guest policy does not allow debugging.
+
+9. KVM_SEV_LAUNCH_SECRET
+------------------------
+
+The KVM_SEV_LAUNCH_SECRET command can be used by the hypervisor to inject secret
+data after the measurement has been validated by the guest owner.
+
+Parameters (in): struct kvm_sev_launch_secret
+
+Returns: 0 on success, -negative on error
+
+::
+
+ struct kvm_sev_launch_secret {
+ __u64 hdr_uaddr; /* userspace address containing the packet header */
+ __u32 hdr_len;
+
+ __u64 guest_uaddr; /* the guest memory region where the secret should be injected */
+ __u32 guest_len;
+
+ __u64 trans_uaddr; /* the hypervisor memory region which contains the secret */
+ __u32 trans_len;
+ };
+
+References
+==========
+
+.. [white-paper] http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf
+.. [api-spec] http://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf
+.. [amd-apm] http://support.amd.com/TechDocs/24593.pdf (section 15.34)
+.. [kvm-forum] http://www.linux-kvm.org/images/7/74/02x08A-Thomas_Lendacky-AMDs_Virtualizatoin_Memory_Encryption_Technology.pdf
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index fc3ae951bc07..792fa8717d13 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1841,6 +1841,7 @@ registers, find a list below:
PPC | KVM_REG_PPC_DBSR | 32
PPC | KVM_REG_PPC_TIDR | 64
PPC | KVM_REG_PPC_PSSCR | 64
+ PPC | KVM_REG_PPC_DEC_EXPIRY | 64
PPC | KVM_REG_PPC_TM_GPR0 | 64
...
PPC | KVM_REG_PPC_TM_GPR31 | 64
@@ -3403,7 +3404,7 @@ invalid, if invalid pages are written to (e.g. after the end of memory)
or if no page table is present for the addresses (e.g. when using
hugepages).
-4.108 KVM_PPC_GET_CPU_CHAR
+4.109 KVM_PPC_GET_CPU_CHAR
Capability: KVM_CAP_PPC_GET_CPU_CHAR
Architectures: powerpc
@@ -3449,6 +3450,57 @@ array bounds check and the array access.
These fields use the same bit definitions as the new
H_GET_CPU_CHARACTERISTICS hypercall.
+4.110 KVM_MEMORY_ENCRYPT_OP
+
+Capability: basic
+Architectures: x86
+Type: system
+Parameters: an opaque platform specific structure (in/out)
+Returns: 0 on success; -1 on error
+
+If the platform supports creating encrypted VMs then this ioctl can be used
+for issuing platform-specific memory encryption commands to manage those
+encrypted VMs.
+
+Currently, this ioctl is used for issuing Secure Encrypted Virtualization
+(SEV) commands on AMD Processors. The SEV commands are defined in
+Documentation/virtual/kvm/amd-memory-encryption.txt.
+
+4.111 KVM_MEMORY_ENCRYPT_REG_REGION
+
+Capability: basic
+Architectures: x86
+Type: system
+Parameters: struct kvm_enc_region (in)
+Returns: 0 on success; -1 on error
+
+This ioctl can be used to register a guest memory region which may
+contain encrypted data (e.g. guest RAM, SMRAM etc).
+
+It is used in the SEV-enabled guest. When encryption is enabled, a guest
+memory region may contain encrypted data. The SEV memory encryption
+engine uses a tweak such that two identical plaintext pages, each at
+different locations will have differing ciphertexts. So swapping or
+moving ciphertext of those pages will not result in plaintext being
+swapped. So relocating (or migrating) physical backing pages for the SEV
+guest will require some additional steps.
+
+Note: The current SEV key management spec does not provide commands to
+swap or migrate (move) ciphertext pages. Hence, for now we pin the guest
+memory region registered with the ioctl.
+
+4.112 KVM_MEMORY_ENCRYPT_UNREG_REGION
+
+Capability: basic
+Architectures: x86
+Type: system
+Parameters: struct kvm_enc_region (in)
+Returns: 0 on success; -1 on error
+
+This ioctl can be used to unregister the guest memory region registered
+with KVM_MEMORY_ENCRYPT_REG_REGION ioctl above.
+
+
5. The kvm_run structure
------------------------
diff --git a/Documentation/virtual/kvm/arm/vgic-mapped-irqs.txt b/Documentation/virtual/kvm/arm/vgic-mapped-irqs.txt
deleted file mode 100644
index 38bca2835278..000000000000
--- a/Documentation/virtual/kvm/arm/vgic-mapped-irqs.txt
+++ /dev/null
@@ -1,187 +0,0 @@
-KVM/ARM VGIC Forwarded Physical Interrupts
-==========================================
-
-The KVM/ARM code implements software support for the ARM Generic
-Interrupt Controller's (GIC's) hardware support for virtualization by
-allowing software to inject virtual interrupts to a VM, which the guest
-OS sees as regular interrupts. The code is famously known as the VGIC.
-
-Some of these virtual interrupts, however, correspond to physical
-interrupts from real physical devices. One example could be the
-architected timer, which itself supports virtualization, and therefore
-lets a guest OS program the hardware device directly to raise an
-interrupt at some point in time. When such an interrupt is raised, the
-host OS initially handles the interrupt and must somehow signal this
-event as a virtual interrupt to the guest. Another example could be a
-passthrough device, where the physical interrupts are initially handled
-by the host, but the device driver for the device lives in the guest OS
-and KVM must therefore somehow inject a virtual interrupt on behalf of
-the physical one to the guest OS.
-
-These virtual interrupts corresponding to a physical interrupt on the
-host are called forwarded physical interrupts, but are also sometimes
-referred to as 'virtualized physical interrupts' and 'mapped interrupts'.
-
-Forwarded physical interrupts are handled slightly differently compared
-to virtual interrupts generated purely by a software emulated device.
-
-
-The HW bit
-----------
-Virtual interrupts are signalled to the guest by programming the List
-Registers (LRs) on the GIC before running a VCPU. The LR is programmed
-with the virtual IRQ number and the state of the interrupt (Pending,
-Active, or Pending+Active). When the guest ACKs and EOIs a virtual
-interrupt, the LR state moves from Pending to Active, and finally to
-inactive.
-
-The LRs include an extra bit, called the HW bit. When this bit is set,
-KVM must also program an additional field in the LR, the physical IRQ
-number, to link the virtual with the physical IRQ.
-
-When the HW bit is set, KVM must EITHER set the Pending OR the Active
-bit, never both at the same time.
-
-Setting the HW bit causes the hardware to deactivate the physical
-interrupt on the physical distributor when the guest deactivates the
-corresponding virtual interrupt.
-
-
-Forwarded Physical Interrupts Life Cycle
-----------------------------------------
-
-The state of forwarded physical interrupts is managed in the following way:
-
- - The physical interrupt is acked by the host, and becomes active on
- the physical distributor (*).
- - KVM sets the LR.Pending bit, because this is the only way the GICV
- interface is going to present it to the guest.
- - LR.Pending will stay set as long as the guest has not acked the interrupt.
- - LR.Pending transitions to LR.Active on the guest read of the IAR, as
- expected.
- - On guest EOI, the *physical distributor* active bit gets cleared,
- but the LR.Active is left untouched (set).
- - KVM clears the LR on VM exits when the physical distributor
- active state has been cleared.
-
-(*): The host handling is slightly more complicated. For some forwarded
-interrupts (shared), KVM directly sets the active state on the physical
-distributor before entering the guest, because the interrupt is never actually
-handled on the host (see details on the timer as an example below). For other
-forwarded interrupts (non-shared) the host does not deactivate the interrupt
-when the host ISR completes, but leaves the interrupt active until the guest
-deactivates it. Leaving the interrupt active is allowed, because Linux
-configures the physical GIC with EOIMode=1, which causes EOI operations to
-perform a priority drop allowing the GIC to receive other interrupts of the
-default priority.
-
-
-Forwarded Edge and Level Triggered PPIs and SPIs
-------------------------------------------------
-Forwarded physical interrupts injected should always be active on the
-physical distributor when injected to a guest.
-
-Level-triggered interrupts will keep the interrupt line to the GIC
-asserted, typically until the guest programs the device to deassert the
-line. This means that the interrupt will remain pending on the physical
-distributor until the guest has reprogrammed the device. Since we
-always run the VM with interrupts enabled on the CPU, a pending
-interrupt will exit the guest as soon as we switch into the guest,
-preventing the guest from ever making progress as the process repeats
-over and over. Therefore, the active state on the physical distributor
-must be set when entering the guest, preventing the GIC from forwarding
-the pending interrupt to the CPU. As soon as the guest deactivates the
-interrupt, the physical line is sampled by the hardware again and the host
-takes a new interrupt if and only if the physical line is still asserted.
-
-Edge-triggered interrupts do not exhibit the same problem with
-preventing guest execution that level-triggered interrupts do. One
-option is to not use HW bit at all, and inject edge-triggered interrupts
-from a physical device as pure virtual interrupts. But that would
-potentially slow down handling of the interrupt in the guest, because a
-physical interrupt occurring in the middle of the guest ISR would
-preempt the guest for the host to handle the interrupt. Additionally,
-if you configure the system to handle interrupts on a separate physical
-core from that running your VCPU, you still have to interrupt the VCPU
-to queue the pending state onto the LR, even though the guest won't use
-this information until the guest ISR completes. Therefore, the HW
-bit should always be set for forwarded edge-triggered interrupts. With
-the HW bit set, the virtual interrupt is injected and additional
-physical interrupts occurring before the guest deactivates the interrupt
-simply mark the state on the physical distributor as Pending+Active. As
-soon as the guest deactivates the interrupt, the host takes another
-interrupt if and only if there was a physical interrupt between injecting
-the forwarded interrupt to the guest and the guest deactivating the
-interrupt.
-
-Consequently, whenever we schedule a VCPU with one or more LRs with the
-HW bit set, the interrupt must also be active on the physical
-distributor.
-
-
-Forwarded LPIs
---------------
-LPIs, introduced in GICv3, are always edge-triggered and do not have an
-active state. They become pending when a device signal them, and as
-soon as they are acked by the CPU, they are inactive again.
-
-It therefore doesn't make sense, and is not supported, to set the HW bit
-for physical LPIs that are forwarded to a VM as virtual interrupts,
-typically virtual SPIs.
-
-For LPIs, there is no other choice than to preempt the VCPU thread if
-necessary, and queue the pending state onto the LR.
-
-
-Putting It Together: The Architected Timer
-------------------------------------------
-The architected timer is a device that signals interrupts with level
-triggered semantics. The timer hardware is directly accessed by VCPUs
-which program the timer to fire at some point in time. Each VCPU on a
-system programs the timer to fire at different times, and therefore the
-hardware is multiplexed between multiple VCPUs. This is implemented by
-context-switching the timer state along with each VCPU thread.
-
-However, this means that a scenario like the following is entirely
-possible, and in fact, typical:
-
-1. KVM runs the VCPU
-2. The guest programs the time to fire in T+100
-3. The guest is idle and calls WFI (wait-for-interrupts)
-4. The hardware traps to the host
-5. KVM stores the timer state to memory and disables the hardware timer
-6. KVM schedules a soft timer to fire in T+(100 - time since step 2)
-7. KVM puts the VCPU thread to sleep (on a waitqueue)
-8. The soft timer fires, waking up the VCPU thread
-9. KVM reprograms the timer hardware with the VCPU's values
-10. KVM marks the timer interrupt as active on the physical distributor
-11. KVM injects a forwarded physical interrupt to the guest
-12. KVM runs the VCPU
-
-Notice that KVM injects a forwarded physical interrupt in step 11 without
-the corresponding interrupt having actually fired on the host. That is
-exactly why we mark the timer interrupt as active in step 10, because
-the active state on the physical distributor is part of the state
-belonging to the timer hardware, which is context-switched along with
-the VCPU thread.
-
-If the guest does not idle because it is busy, the flow looks like this
-instead:
-
-1. KVM runs the VCPU
-2. The guest programs the time to fire in T+100
-4. At T+100 the timer fires and a physical IRQ causes the VM to exit
- (note that this initially only traps to EL2 and does not run the host ISR
- until KVM has returned to the host).
-5. With interrupts still disabled on the CPU coming back from the guest, KVM
- stores the virtual timer state to memory and disables the virtual hw timer.
-6. KVM looks at the timer state (in memory) and injects a forwarded physical
- interrupt because it concludes the timer has expired.
-7. KVM marks the timer interrupt as active on the physical distributor
-7. KVM enables the timer, enables interrupts, and runs the VCPU
-
-Notice that again the forwarded physical interrupt is injected to the
-guest without having actually been handled on the host. In this case it
-is because the physical interrupt is never actually seen by the host because the
-timer is disabled upon guest return, and the virtual forwarded interrupt is
-injected on the KVM guest entry path.
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index 3c65feb83010..dcab6dc11e3b 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -54,6 +54,10 @@ KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit
|| || before enabling paravirtualized
|| || spinlock support.
------------------------------------------------------------------------------
+KVM_FEATURE_PV_TLB_FLUSH || 9 || guest checks this feature bit
+ || || before enabling paravirtualized
+ || || tlb flush.
+------------------------------------------------------------------------------
KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
|| || per-cpu warps are expected in
|| || kvmclock.