From: Paolo Bonzini Date: Tue, 30 Nov 2021 08:46:07 +0000 (-0500) Subject: KVM: fix avic_set_running for preemptable kernels X-Git-Tag: v6.1-rc5~2050^2~288 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7cfc5c653b07782e7059527df8dc1e3143a7591e;p=platform%2Fkernel%2Flinux-starfive.git KVM: fix avic_set_running for preemptable kernels avic_set_running() passes the current CPU to avic_vcpu_load(), albeit via vcpu->cpu rather than smp_processor_id(). If the thread is migrated while avic_set_running runs, the call to avic_vcpu_load() can use a stale value for the processor id. Avoid this by blocking preemption over the entire execution of avic_set_running(). Reported-by: Sean Christopherson Fixes: 8221c1370056 ("svm: Manage vcpu load/unload when enable AVIC") Cc: stable@vger.kernel.org Reviewed-by: Maxim Levitsky Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index affc0ea..9d6066e 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -989,16 +989,18 @@ void avic_vcpu_put(struct kvm_vcpu *vcpu) static void avic_set_running(struct kvm_vcpu *vcpu, bool is_run) { struct vcpu_svm *svm = to_svm(vcpu); + int cpu = get_cpu(); + WARN_ON(cpu != vcpu->cpu); svm->avic_is_running = is_run; - if (!kvm_vcpu_apicv_active(vcpu)) - return; - - if (is_run) - avic_vcpu_load(vcpu, vcpu->cpu); - else - avic_vcpu_put(vcpu); + if (kvm_vcpu_apicv_active(vcpu)) { + if (is_run) + avic_vcpu_load(vcpu, cpu); + else + avic_vcpu_put(vcpu); + } + put_cpu(); } void svm_vcpu_blocking(struct kvm_vcpu *vcpu)