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From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Subject: [PATCH v2 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest
Date: Tue, 28 May 2019 08:53:15 +0800	[thread overview]
Message-ID: <1559004795-19927-4-git-send-email-wanpengli@tencent.com> (raw)
In-Reply-To: <1559004795-19927-1-git-send-email-wanpengli@tencent.com>

From: Wanpeng Li <wanpengli@tencent.com>

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 Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.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 97ca194..1c39683 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_SHED_YIELD          ||    12 || 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 e18a9f9..c018fc8 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -643,7 +643,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 			     (1 << KVM_FEATURE_PV_UNHALT) |
 			     (1 << KVM_FEATURE_PV_TLB_FLUSH) |
 			     (1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
-			     (1 << KVM_FEATURE_PV_SEND_IPI);
+			     (1 << KVM_FEATURE_PV_SEND_IPI) |
+			     (1 << KVM_FEATURE_PV_SCHED_YIELD);
 
 		if (sched_info_on())
 			entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
-- 
2.7.4


      parent reply	other threads:[~2019-05-28  0:53 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28  0:53 [PATCH v2 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-05-28  0:53 ` [PATCH v2 1/3] KVM: X86: Implement PV sched yield in linux guest Wanpeng Li
2019-05-28  0:53 ` [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-05-28  2:15   ` [PATCH RESEND v2] " Wanpeng Li
2019-05-28  6:08     ` kbuild test robot
2019-05-28  6:14       ` Wanpeng Li
2019-05-28  7:23     ` kbuild test robot
2019-05-28  7:50   ` [PATCH RESEND v2 0/3] KVM: Yield to IPI target if necessary Wanpeng Li
2019-05-28  7:50     ` [PATCH RESEND v2 1/3] KVM: X86: Implement PV sched yield in linux guest Wanpeng Li
2019-05-28  7:50     ` [PATCH RESEND v2 2/3] KVM: X86: Implement PV sched yield hypercall Wanpeng Li
2019-05-28  7:50     ` [PATCH RESEND v2 3/3] KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest Wanpeng Li
2019-05-28  9:11   ` [PATCH v2 2/3] KVM: X86: Implement PV sched yield hypercall Christian Borntraeger
2019-05-28  9:57     ` Wanpeng Li
2019-05-29 12:28   ` Liran Alon
2019-05-30  1:09     ` Wanpeng Li
2019-05-28  0:53 ` Wanpeng Li [this message]

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