From a1fa4cbd53d9bc7bb0eaa7bcf7c8a5904372a4ec Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Fri, 9 Apr 2021 12:18:31 +0800 Subject: [PATCH] KVM: X86: Do not yield to self If the target is self we do not need to yield, we can avoid malicious guest to play this. Signed-off-by: Wanpeng Li Message-Id: <1617941911-5338-3-git-send-email-wanpengli@tencent.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- 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 05a4bce181d7..66d2ab074a5f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8228,6 +8228,10 @@ 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; -- 2.20.1