Commit cae72dcc authored by Maxim Levitsky's avatar Maxim Levitsky Committed by Paolo Bonzini
Browse files

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: 61e5f69e ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")

Reported-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Tested-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211108090245.166408-1-mlevitsk@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent e6cd31f1

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/svm/avic.c

+2 −1
Original line number Diff line number Diff line
@@ -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);

}

arch/x86/kvm/vmx/vmx.c

+2 −1
Original line number Diff line number Diff line
@@ -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);

}

arch/x86/kvm/x86.c

+20 −0
Original line number Diff line number Diff line
@@ -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: