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authorSuravee Suthikulpanit2019-11-14 14:15:14 -0600
committerPaolo Bonzini2020-02-05 15:17:43 +0100
commit9a0bf05430699dc94b7ced940f6270c7cf1d77ef (patch)
tree5c88a9e9a81cbf399dcc2eb6a9458aeadc5f9ce2 /arch
parentf4fdc0a2edf48f16f7b10cceaf4781fc56ab7fd9 (diff)
svm: Deactivate AVIC when launching guest with nested SVM support
Since AVIC does not currently work w/ nested virtualization, deactivate AVIC for the guest if setting CPUID Fn80000001_ECX[SVM] (i.e. indicate support for SVM, which is needed for nested virtualization). Also, introduce a new APICV_INHIBIT_REASON_NESTED bit to be used for this reason. Suggested-by: Alexander Graf <graf@amazon.com> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/kvm_host.h1
-rw-r--r--arch/x86/kvm/svm.c11
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 90bfe8becc56..ce19dea5f2dd 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -877,6 +877,7 @@ enum kvm_irqchip_mode {
#define APICV_INHIBIT_REASON_DISABLE 0
#define APICV_INHIBIT_REASON_HYPERV 1
+#define APICV_INHIBIT_REASON_NESTED 2
struct kvm_arch {
unsigned long n_used_mmu_pages;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 3b87ccd320d1..af90f83d7123 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -5988,6 +5988,14 @@ 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))
+ kvm_request_apicv_update(vcpu->kvm, false,
+ APICV_INHIBIT_REASON_NESTED);
}
#define F feature_bit
@@ -7319,7 +7327,8 @@ static bool svm_apic_init_signal_blocked(struct kvm_vcpu *vcpu)
static bool svm_check_apicv_inhibit_reasons(ulong bit)
{
ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
- BIT(APICV_INHIBIT_REASON_HYPERV);
+ BIT(APICV_INHIBIT_REASON_HYPERV) |
+ BIT(APICV_INHIBIT_REASON_NESTED);
return supported & BIT(bit);
}