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Message-Id: <20200525144125.143875-8-vkuznets@redhat.com>
Date: Mon, 25 May 2020 16:41:22 +0200
From: Vitaly Kuznetsov <vkuznets@...hat.com>
To: kvm@...r.kernel.org, x86@...nel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
"H. Peter Anvin" <hpa@...or.com>,
Wanpeng Li <wanpengli@...cent.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Jim Mattson <jmattson@...gle.com>,
Vivek Goyal <vgoyal@...hat.com>, Gavin Shan <gshan@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 07/10] 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@...hat.com>
---
Documentation/virt/kvm/cpuid.rst | 6 ++++++
Documentation/virt/kvm/msr.rst | 12 ++++++++----
arch/x86/include/uapi/asm/kvm_para.h | 1 +
arch/x86/kvm/cpuid.c | 3 ++-
arch/x86/kvm/x86.c | 1 +
include/uapi/linux/kvm.h | 1 +
6 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/Documentation/virt/kvm/cpuid.rst b/Documentation/virt/kvm/cpuid.rst
index 01b081f6e7ea..98cbd257ac33 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 8ea3fbcc67fd..d409cc26193f 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
@@ -243,7 +244,8 @@ 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
@@ -361,7 +363,8 @@ 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
@@ -372,4 +375,5 @@ 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 caused 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.
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 7ac20df80ba8..812e9b4c1114 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -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
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 901cd1fdecd9..790fe4988001 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -712,7 +712,8 @@ 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);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ffe1497b7beb..cc1bf6cfc5e0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3404,6 +3404,7 @@ 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:
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 428c7dde6b4b..15012f78a691 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1017,6 +1017,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_S390_VCPU_RESETS 179
#define KVM_CAP_S390_PROTECTED 180
#define KVM_CAP_PPC_SECURE_GUEST 181
+#define KVM_CAP_ASYNC_PF_INT 182
#ifdef KVM_CAP_IRQ_ROUTING
--
2.25.4
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