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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: 61e5f69ef0 ("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>
This commit is contained in:
Maxim Levitsky 2021-11-08 11:02:45 +02:00 committed by Paolo Bonzini
parent e6cd31f1a8
commit cae72dcc3b
4 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/kvm_host.h
View File

@ -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;

3
arch/x86/kvm/svm/avic.c
View File

@ -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);
}

3
arch/x86/kvm/vmx/vmx.c
View File

@ -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);
}

20
arch/x86/kvm/x86.c
View File

@ -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: