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authorPaolo Bonzini <pbonzini@redhat.com>2021-11-30 11:46:07 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2021-11-30 15:40:48 +0300
commit7cfc5c653b07782e7059527df8dc1e3143a7591e (patch)
treea5b87c639298951bfee39ba9e2b14f36d9dd6af8 /arch
parente90e51d5f01d2baae5dcce280866bbb96816e978 (diff)
downloadlinux-7cfc5c653b07782e7059527df8dc1e3143a7591e.tar.xz
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 <seanjc@google.com> Fixes: 8221c1370056 ("svm: Manage vcpu load/unload when enable AVIC") Cc: stable@vger.kernel.org Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/svm/avic.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index affc0ea98d30..9d6066eb7c10 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)