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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 v2 3/3] KVM: X86: Do not yield to self
Date: Fri,  9 Apr 2021 12:18:31 +0800	[thread overview]
Message-ID: <1617941911-5338-3-git-send-email-wanpengli@tencent.com> (raw)
In-Reply-To: <1617941911-5338-1-git-send-email-wanpengli@tencent.com>

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>
---
v1 -> v2:
 * update comments

 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 f08e9b4..ce9a1d2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8231,6 +8231,10 @@ static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id)
 	if (!target || !READ_ONCE(target->ready))
 		goto no_yield;
 
+	/* Ignore requests to yield to self */
+	if (vcpu == target)
+		goto no_yield;
+
 	if (kvm_vcpu_yield_to(target) <= 0)
 		goto no_yield;
 
-- 
2.7.4


  parent reply	other threads:[~2021-04-09  4:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-09  4:18 [PATCH v2 1/3] x86/kvm: Don't bother __pv_cpu_mask when !CONFIG_SMP Wanpeng Li
2021-04-09  4:18 ` [PATCH v2 2/3] KVM: X86: Count attempted/successful directed yield Wanpeng Li
2021-04-09  4:18 ` Wanpeng Li [this message]
2021-04-17 12:34 ` [PATCH v2 1/3] x86/kvm: Don't bother __pv_cpu_mask when !CONFIG_SMP Paolo Bonzini

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