linux-kernel - [PATCH v3 12/26] KVM: SVM: Remove unnecessary APICv/AVIC update in vCPU unblocking path

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Message-Id: <20211208015236.1616697-13-seanjc@google.com>
Date:   Wed,  8 Dec 2021 01:52:22 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, Joerg Roedel <joro@...tes.org>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        kvm@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v3 12/26] KVM: SVM: Remove unnecessary APICv/AVIC update in
 vCPU unblocking path

Remove handling of KVM_REQ_APICV_UPDATE from svm_vcpu_unblocking(), it's
no longer needed as it was made obsolete by commit df7e4827c549 ("KVM:
SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC").
Prior to that commit, the manual check was necessary to ensure the AVIC
stuff was updated by avic_set_running() when a request to enable APICv
became pending while the vCPU was blocking, as the request handling
itself would not do the update.  But, as evidenced by the commit, that
logic was flawed and subject to various races.

Now that svm_refresh_apicv_exec_ctrl() does avic_vcpu_load/put() in
response to an APICv status change, drop the manual check in the
unblocking path.

Suggested-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/avic.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 37575b71cdf3..16e4ebd980a2 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -1039,7 +1039,5 @@ void svm_vcpu_blocking(struct kvm_vcpu *vcpu)

 void svm_vcpu_unblocking(struct kvm_vcpu *vcpu)
 {
-	if (kvm_check_request(KVM_REQ_APICV_UPDATE, vcpu))
-		kvm_vcpu_update_apicv(vcpu);
 	avic_set_running(vcpu, true);
 }
-- 
2.34.1.400.ga245620fadb-goog