linux-kernel - [PATCH 2/4] KVM: x86: SVM: disable preemption in avic_refresh_apicv_exec

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Date:   Tue,  1 Mar 2022 15:55:24 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Jim Mattson <jmattson@...gle.com>,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH 2/4] KVM: x86: SVM: disable preemption in avic_refresh_apicv_exec_ctrl

avic_refresh_apicv_exec_ctrl is called from vcpu_enter_guest,
without preemption disabled, however avic_vcpu_load, and
avic_vcpu_put expect preemption to be disabled.

This issue was found by lockdep.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/avic.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index aea0b13773fd3..e23159f3a62ba 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -640,12 +640,16 @@ void avic_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
 	}
 	vmcb_mark_dirty(vmcb, VMCB_AVIC);
 
+	preempt_disable();
+
 	if (activated)
 		avic_vcpu_load(vcpu, vcpu->cpu);
 	else
 		avic_vcpu_put(vcpu);
 
 	avic_set_pi_irte_mode(vcpu, activated);
+
+	preempt_enable();
 }
 
 static void svm_ir_list_del(struct vcpu_svm *svm, struct amd_iommu_pi_data *pi)
-- 
2.26.3