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KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT

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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>
This commit is contained in:
Vitaly Kuznetsov 2020-05-25 16:41:22 +02:00 committed by Paolo Bonzini
parent 557a961abb
commit 72de5fa4c1
6 changed files with 19 additions and 5 deletions
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6
Documentation/virt/kvm/cpuid.rst
View File

@ -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

12
Documentation/virt/kvm/msr.rst
View File

@ -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.

1
arch/x86/include/uapi/asm/kvm_para.h
View File

@ -31,6 +31,7 @@
#define KVM_FEATURE_PV_SEND_IPI 11
#define KVM_FEATURE_POLL_CONTROL 12
#define KVM_FEATURE_PV_SCHED_YIELD 13
#define KVM_FEATURE_ASYNC_PF_INT 14
#define KVM_HINTS_REALTIME 0

3
arch/x86/kvm/cpuid.c
View File

@ -711,7 +711,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
(1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
(1 << KVM_FEATURE_PV_SEND_IPI) |
(1 << KVM_FEATURE_POLL_CONTROL) |
(1 << KVM_FEATURE_PV_SCHED_YIELD);
(1 << KVM_FEATURE_PV_SCHED_YIELD) |
(1 << KVM_FEATURE_ASYNC_PF_INT);
if (sched_info_on())
entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);

1
arch/x86/kvm/x86.c
View File

@ -3446,6 +3446,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_X86_ROBUST_SINGLESTEP:
case KVM_CAP_XSAVE:
case KVM_CAP_ASYNC_PF:
case KVM_CAP_ASYNC_PF_INT:
case KVM_CAP_GET_TSC_KHZ:
case KVM_CAP_KVMCLOCK_CTRL:
case KVM_CAP_READONLY_MEM:

1
include/uapi/linux/kvm.h
View File

@ -1018,6 +1018,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_S390_PROTECTED 180
#define KVM_CAP_PPC_SECURE_GUEST 181
#define KVM_CAP_HALT_POLL 182
#define KVM_CAP_ASYNC_PF_INT 183
#ifdef KVM_CAP_IRQ_ROUTING