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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>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: [PATCH] KVM: X86: Do not yield to self
Date: Thu,  8 Apr 2021 19:23:09 +0800	[thread overview]
Message-ID: <1617880989-8019-1-git-send-email-wanpengli@tencent.com> (raw)

From: Wanpeng Li <wanpengli@tencent.com>

If the target is self we do not need to yield, we can avoid malicious 
guest to play this.

Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
Rebased on https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpengli@tencent.com/

 arch/x86/kvm/x86.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 43c9f9b..260650f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8230,6 +8230,10 @@ static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id)
 	if (!target)
 		goto no_yield;
 
+	/* yield to self */
+	if (vcpu->vcpu_id == target->vcpu_id)
+		goto no_yield;
+
 	if (!READ_ONCE(target->ready))
 		goto no_yield;
 
-- 
2.7.4


             reply	other threads:[~2021-04-08 11:23 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-08 11:23 Wanpeng Li [this message]
2021-04-08 16:56 ` [PATCH] KVM: X86: Do not yield to self Sean Christopherson
2021-04-09  3:05   ` Wanpeng Li

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