From 32b72ecc83b651fb8633ac4bd44957c54367699d Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpengli@tencent.com>
Date: Tue, 11 Jun 2019 20:23:50 +0800
Subject: [PATCH] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest
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Expose PV_SCHED_YIELD feature bit to guest, the guest can check this
feature bit before using paravirtualized sched yield.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
Documentation/virtual/kvm/cpuid.txt | 4 ++++
arch/x86/kvm/cpuid.c | 3 ++-
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index 97ca1940a0dc9..979a77ba5377b 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -66,6 +66,10 @@ KVM_FEATURE_PV_SEND_IPI || 11 || guest checks this feature bit
|| || before using paravirtualized
|| || send IPIs.
------------------------------------------------------------------------------
+KVM_FEATURE_PV_SCHED_YIELD || 13 || guest checks this feature bit
+ || || before using paravirtualized
+ || || sched yield.
+------------------------------------------------------------------------------
KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
|| || per-cpu warps are expected in
|| || kvmclock.
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 68c74e948e28a..004cbd84c3519 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -659,7 +659,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
(1 << KVM_FEATURE_PV_TLB_FLUSH) |
(1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
(1 << KVM_FEATURE_PV_SEND_IPI) |
- (1 << KVM_FEATURE_POLL_CONTROL);
+ (1 << KVM_FEATURE_POLL_CONTROL) |
+ (1 << KVM_FEATURE_PV_SCHED_YIELD);
if (sched_info_on())
entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
--
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