linux-kernel - [PATCH 9/9] KVM: SVM: Skip intercepted PAUSE instructions after emulation

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Message-Id: <20210205005750.3841462-10-seanjc@google.com>
Date:   Thu,  4 Feb 2021 16:57:50 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Jiri Kosina <trivial@...nel.org>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 9/9] KVM: SVM: Skip intercepted PAUSE instructions after emulation

Skip PAUSE after interception to avoid unnecessarily re-executing the
instruction in the guest, e.g. after regaining control post-yield.
This is a benign bug as KVM disables PAUSE interception if filtering is
off, including the case where pause_filter_count is set to zero.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b6acc73d356a..ac634b9eba8a 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2992,7 +2992,7 @@ static int pause_interception(struct kvm_vcpu *vcpu)
 		grow_ple_window(vcpu);
 
 	kvm_vcpu_on_spin(vcpu, in_kernel);
-	return 1;
+	return kvm_skip_emulated_instruction(vcpu);
 }
 
 static int invpcid_interception(struct kvm_vcpu *vcpu)
-- 
2.30.0.365.g02bc693789-goog