KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active
KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using
standard kvm's inject_pending_event, and not via APICv/AVIC.
Since this is a debug feature, just inhibit APICv/AVIC while
KVM_GUESTDBG_BLOCKIRQ is in use on at least one vCPU.
Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")
Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Tested-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211108090245.166408-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3234524..b71023c6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1034,6 +1034,7 @@ struct kvm_x86_msr_filter {
#define APICV_INHIBIT_REASON_IRQWIN 3
#define APICV_INHIBIT_REASON_PIT_REINJ 4
#define APICV_INHIBIT_REASON_X2APIC 5
+#define APICV_INHIBIT_REASON_BLOCKIRQ 6
struct kvm_arch {
unsigned long n_used_mmu_pages;
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 8052d92..affc0ea 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -904,7 +904,8 @@ bool svm_check_apicv_inhibit_reasons(ulong bit)
BIT(APICV_INHIBIT_REASON_NESTED) |
BIT(APICV_INHIBIT_REASON_IRQWIN) |
BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
- BIT(APICV_INHIBIT_REASON_X2APIC);
+ BIT(APICV_INHIBIT_REASON_X2APIC) |
+ BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
return supported & BIT(bit);
}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 71f54d8..e4fc9ff 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7565,7 +7565,8 @@ static void hardware_unsetup(void)
static bool vmx_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_BLOCKIRQ);
return supported & BIT(bit);
}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6bfef1d..d7d2f1b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10753,6 +10753,24 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
return ret;
}
+static void kvm_arch_vcpu_guestdbg_update_apicv_inhibit(struct kvm *kvm)
+{
+ bool inhibit = false;
+ struct kvm_vcpu *vcpu;
+ int i;
+
+ down_write(&kvm->arch.apicv_update_lock);
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ) {
+ inhibit = true;
+ break;
+ }
+ }
+ __kvm_request_apicv_update(kvm, !inhibit, APICV_INHIBIT_REASON_BLOCKIRQ);
+ up_write(&kvm->arch.apicv_update_lock);
+}
+
int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg)
{
@@ -10805,6 +10823,8 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
static_call(kvm_x86_update_exception_bitmap)(vcpu);
+ kvm_arch_vcpu_guestdbg_update_apicv_inhibit(vcpu->kvm);
+
r = 0;
out:
