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authorVitaly Kuznetsov <vkuznets@redhat.com>2020-05-25 17:41:22 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2020-06-01 11:26:08 +0300
commit72de5fa4c16195827252b961ba44028a39dfeaff (patch)
treee662fd0440ec378bd99ce131cee9b51f08bb0863 /Documentation/virt
parent557a961abbe06ed9dfd3b55ef7bd6e68295cda3d (diff)
downloadlinux-72de5fa4c16195827252b961ba44028a39dfeaff.tar.xz
KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT
Introduce new capability to indicate that KVM supports interrupt based delivery of 'page ready' APF events. This includes support for both MSR_KVM_ASYNC_PF_INT and MSR_KVM_ASYNC_PF_ACK. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20200525144125.143875-8-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virt')
-rw-r--r--Documentation/virt/kvm/cpuid.rst6
-rw-r--r--Documentation/virt/kvm/msr.rst12
2 files changed, 14 insertions, 4 deletions
diff --git a/Documentation/virt/kvm/cpuid.rst b/Documentation/virt/kvm/cpuid.rst
index f721c89327ec..a7dff9186bed 100644
--- a/Documentation/virt/kvm/cpuid.rst
+++ b/Documentation/virt/kvm/cpuid.rst
@@ -86,6 +86,12 @@ KVM_FEATURE_PV_SCHED_YIELD 13 guest checks this feature bit
before using paravirtualized
sched yield.
+KVM_FEATURE_ASYNC_PF_INT 14 guest checks this feature bit
+ before using the second async
+ pf control msr 0x4b564d06 and
+ async pf acknowledgment msr
+ 0x4b564d07.
+
KVM_FEATURE_CLOCSOURCE_STABLE_BIT 24 host will warn if no guest-side
per-cpu warps are expeced in
kvmclock
diff --git a/Documentation/virt/kvm/msr.rst b/Documentation/virt/kvm/msr.rst
index 9b107889b033..e37a14c323d2 100644
--- a/Documentation/virt/kvm/msr.rst
+++ b/Documentation/virt/kvm/msr.rst
@@ -213,7 +213,8 @@ data:
cpl == 0. Bit 2 is 1 if asynchronous page faults are delivered to L1 as
#PF vmexits. Bit 2 can be set only if KVM_FEATURE_ASYNC_PF_VMEXIT is
present in CPUID. Bit 3 enables interrupt based delivery of 'page ready'
- events.
+ events. Bit 3 can only be set if KVM_FEATURE_ASYNC_PF_INT is present in
+ CPUID.
'Page not present' events are currently always delivered as synthetic
#PF exception. During delivery of these events APF CR2 register contains
@@ -242,7 +243,8 @@ data:
Note, MSR_KVM_ASYNC_PF_INT MSR specifying the interrupt vector for 'page
ready' APF delivery needs to be written to before enabling APF mechanism
- in MSR_KVM_ASYNC_PF_EN or interrupt #0 can get injected.
+ in MSR_KVM_ASYNC_PF_EN or interrupt #0 can get injected. The MSR is
+ available if KVM_FEATURE_ASYNC_PF_INT is present in CPUID.
Note, previously, 'page ready' events were delivered via the same #PF
exception as 'page not present' events but this is now deprecated. If
@@ -360,7 +362,8 @@ data:
Interrupt vector for asynchnonous 'page ready' notifications delivery.
The vector has to be set up before asynchronous page fault mechanism
- is enabled in MSR_KVM_ASYNC_PF_EN.
+ is enabled in MSR_KVM_ASYNC_PF_EN. The MSR is only available if
+ KVM_FEATURE_ASYNC_PF_INT is present in CPUID.
MSR_KVM_ASYNC_PF_ACK:
0x4b564d07
@@ -371,4 +374,5 @@ data:
When the guest is done processing 'page ready' APF event and 'token'
field in 'struct kvm_vcpu_pv_apf_data' is cleared it is supposed to
write '1' to bit 0 of the MSR, this causes the host to re-scan its queue
- and check if there are more notifications pending.
+ and check if there are more notifications pending. The MSR is available
+ if KVM_FEATURE_ASYNC_PF_INT is present in CPUID.