Currently, AVIC is inhibited when booting a VM w/ x2APIC support.
because AVIC cannot virtualize x2APIC MSR register accesses.
However, the AVIC doorbell can be used to accelerate interrupt
injection into a running vCPU, while all guest accesses to x2APIC MSRs
will be intercepted and emulated by KVM.
With hybrid-AVIC support, the APICV_INHIBIT_REASON_X2APIC is
no longer enforced.
Suggested-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
arch/x86/kvm/svm/avic.c | 10 +++++++++-
arch/x86/kvm/svm/svm.c | 9 ---------
2 files changed, 9 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index d07c58f06bed..3b6a96043633 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -92,12 +92,20 @@ static void avic_activate_vmcb(struct vcpu_svm *svm)
vmcb->control.avic_physical_id &= ~AVIC_PHYSICAL_MAX_INDEX_MASK;
vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
- if (apic_x2apic_mode(svm->vcpu.arch.apic)) {
+
+ /* Note:
+ * KVM can support hybrid-x2AVIC mode, where KVM emulates x2APIC
+ * MSR accesses, while interrupt injection to a running vCPU
+ * can be achieve using AVIC doorbell.
+ */
+ if (apic_x2apic_mode(svm->vcpu.arch.apic) &&
+ (avic_mode == AVIC_MODE_X2)) {
vmcb->control.int_ctl |= X2APIC_MODE_MASK;
vmcb->control.avic_physical_id |= X2AVIC_MAX_PHYSICAL_ID;
/* Disabling MSR intercept for x2APIC registers */
avic_set_x2apic_msr_interception(svm, false);
} else {
+ /* For xAVIC and hybrid-x2AVIC modes */
vmcb->control.avic_physical_id |= AVIC_MAX_PHYSICAL_ID;
/* Enabling MSR intercept for x2APIC registers */
avic_set_x2apic_msr_interception(svm, true);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 96a1fc1a1d1b..c0a3d4a1f3dc 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4041,7 +4041,6 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
struct kvm_cpuid_entry2 *best;
- struct kvm *kvm = vcpu->kvm;
vcpu->arch.xsaves_enabled = guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) &&
boot_cpu_has(X86_FEATURE_XSAVE) &&
@@ -4073,14 +4072,6 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
vcpu->arch.reserved_gpa_bits &= ~(1UL << (best->ebx & 0x3f));
}
- if (kvm_vcpu_apicv_active(vcpu)) {
- /*
- * AVIC does not work with an x2APIC mode guest. If the X2APIC feature
- * is exposed to the guest, disable AVIC.
- */
- if (guest_cpuid_has(vcpu, X86_FEATURE_X2APIC))
- kvm_set_apicv_inhibit(kvm, APICV_INHIBIT_REASON_X2APIC);
- }
init_vmcb_after_set_cpuid(vcpu);
}
--
2.25.1
