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Subject[PATCH v2 3/3] KVM: SVM: Add irqchip_split() checks before enabling AVIC
Date
SVM AVIC hardware accelerates guest write to APIC_EOI register
(for edge-trigger interrupt), which means it does not trap to KVM.

So, only enable SVM AVIC only in split irqchip mode.
(e.g. launching qemu w/ option '-machine kernel_irqchip=split').

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
arch/x86/kvm/svm.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index d1b3eb4..a7b96e7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1176,7 +1176,6 @@ static void avic_init_vmcb(struct vcpu_svm *svm)
vmcb->control.avic_physical_id = ppa & AVIC_HPA_MASK;
vmcb->control.avic_physical_id |= AVIC_MAX_PHYSICAL_ID_COUNT;
vmcb->control.int_ctl |= AVIC_ENABLE_MASK;
- svm->vcpu.arch.apicv_active = true;
}

static void init_vmcb(struct vcpu_svm *svm)
@@ -1292,7 +1291,7 @@ static void init_vmcb(struct vcpu_svm *svm)
set_intercept(svm, INTERCEPT_PAUSE);
}

- if (avic)
+ if (kvm_vcpu_apicv_active(&svm->vcpu))
avic_init_vmcb(svm);

/*
@@ -1594,6 +1593,12 @@ static int avic_init_vcpu(struct vcpu_svm *svm)
if (!avic)
return 0;

+ if (!kvm_vcpu_apicv_active(&svm->vcpu)) {
+ pr_debug("%s: Disable AVIC due to non-split irqchip.\n",
+ __func__);
+ return 0;
+ }
+
ret = avic_init_backing_page(&svm->vcpu);
if (ret)
return ret;
@@ -4388,7 +4393,7 @@ static void svm_set_virtual_x2apic_mode(struct kvm_vcpu *vcpu, bool set)

static bool svm_get_enable_apicv(struct kvm_vcpu *vcpu)
{
- return avic;
+ return avic && irqchip_split(vcpu->kvm);
}

static void svm_hwapic_irr_update(struct kvm_vcpu *vcpu, int max_irr)
@@ -4405,7 +4410,7 @@ static void svm_refresh_apicv_exec_ctrl(struct kvm_vcpu *vcpu)
struct vcpu_svm *svm = to_svm(vcpu);
struct vmcb *vmcb = svm->vmcb;

- if (!avic)
+ if (!kvm_vcpu_apicv_active(&svm->vcpu))
return;

vmcb->control.int_ctl &= ~AVIC_ENABLE_MASK;
--
1.8.3.1
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