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Subject[PATCH v3 10/16] svm: Disable AVIC when launching guest with SVM support
Date
Since AVIC does not currently work w/ nested virtualization, disable AVIC
for the guest if setting CPUID Fn80000001_ECX[SVM] (i.e. indicate support
for SVM, which is needed for nested virtualization).

Suggested-by: Alexander Graf <graf@amazon.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/kvm/svm.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a01bc6a..e02ee1a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6029,6 +6029,16 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
return;

guest_cpuid_clear(vcpu, X86_FEATURE_X2APIC);
+
+ /*
+ * Currently, AVIC does not work with nested virtualization.
+ * So, we disable AVIC when cpuid for SVM is set in the L1 guest.
+ */
+ if (nested && guest_cpuid_has(vcpu, X86_FEATURE_SVM)) {
+ vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+ kvm_make_apicv_deactivate_request(vcpu, true);
+ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
+ }
}

static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
--
1.8.3.1
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