Commit 7e5b5ef8 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: SVM: Re-inject INTn instead of retrying the insn on "failure" 



Re-inject INTn software interrupts instead of retrying the instruction if
the CPU encountered an intercepted exception while vectoring the INTn,
e.g. if KVM intercepted a #PF when utilizing shadow paging.  Retrying the
instruction is architecturally wrong e.g. will result in a spurious #DB
if there's a code breakpoint on the INT3/O, and lack of re-injection also
breaks nested virtualization, e.g. if L1 injects a software interrupt and
vectoring the injected interrupt encounters an exception that is
intercepted by L0 but not L1.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarMaciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <1654ad502f860948e4f2d57b8bd881d67301f785.1651440202.git.maciej.szmigiero@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 6ef88d6e

arch/x86/kvm/svm/nested.c

+3 −4
Original line number Diff line number Diff line
@@ -617,10 +617,9 @@ static inline bool is_evtinj_soft(u32 evtinj) 
	if (!(evtinj & SVM_EVTINJ_VALID))

		return false;



	/*

	 * Intentionally return false for SOFT events, SVM doesn't yet support

	 * re-injecting soft interrupts.

	 */

	if (type == SVM_EVTINJ_TYPE_SOFT)

		return true;



	return type == SVM_EVTINJ_TYPE_EXEPT && kvm_exception_is_soft(vector);

}

arch/x86/kvm/svm/svm.c

+19 −4
Original line number Diff line number Diff line
@@ -3438,12 +3438,22 @@ static void svm_inject_nmi(struct kvm_vcpu *vcpu) 
static void svm_inject_irq(struct kvm_vcpu *vcpu)

{

	struct vcpu_svm *svm = to_svm(vcpu);

	u32 type;



	if (vcpu->arch.interrupt.soft) {

		if (svm_update_soft_interrupt_rip(vcpu))

			return;



		type = SVM_EVTINJ_TYPE_SOFT;

	} else {

		type = SVM_EVTINJ_TYPE_INTR;

	}



	trace_kvm_inj_virq(vcpu->arch.interrupt.nr);

	++vcpu->stat.irq_injections;



	svm->vmcb->control.event_inj = vcpu->arch.interrupt.nr |

		SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR;

				       SVM_EVTINJ_VALID | type;

}



void svm_complete_interrupt_delivery(struct kvm_vcpu *vcpu, int delivery_mode,
@@ -3723,6 +3733,8 @@ static inline void sync_lapic_to_cr8(struct kvm_vcpu *vcpu) 
static void svm_complete_soft_interrupt(struct kvm_vcpu *vcpu, u8 vector,

					int type)

{

	bool is_exception = (type == SVM_EXITINTINFO_TYPE_EXEPT);

	bool is_soft = (type == SVM_EXITINTINFO_TYPE_SOFT);

	struct vcpu_svm *svm = to_svm(vcpu);



	/*
@@ -3734,8 +3746,7 @@ static void svm_complete_soft_interrupt(struct kvm_vcpu *vcpu, u8 vector, 
	 * the same event, i.e. if the event is a soft exception/interrupt,

	 * otherwise next_rip is unused on VMRUN.

	 */

	if (nrips && type == SVM_EXITINTINFO_TYPE_EXEPT &&

	    kvm_exception_is_soft(vector) &&

	if (nrips && (is_soft || (is_exception && kvm_exception_is_soft(vector))) &&

	    kvm_is_linear_rip(vcpu, svm->soft_int_old_rip + svm->soft_int_csbase))

		svm->vmcb->control.next_rip = svm->soft_int_next_rip;

	/*
@@ -3746,7 +3757,7 @@ static void svm_complete_soft_interrupt(struct kvm_vcpu *vcpu, u8 vector, 
	 * hit a #NP in the guest, and the #NP encountered a #PF, the #NP will

	 * be the reported vectored event, but RIP still needs to be unwound.

	 */

	else if (!nrips && type == SVM_EXITINTINFO_TYPE_EXEPT &&

	else if (!nrips && (is_soft || is_exception) &&

		 kvm_is_linear_rip(vcpu, svm->soft_int_next_rip + svm->soft_int_csbase))

		kvm_rip_write(vcpu, svm->soft_int_old_rip);

}
@@ -3808,9 +3819,13 @@ static void svm_complete_interrupts(struct kvm_vcpu *vcpu) 
	case SVM_EXITINTINFO_TYPE_INTR:

		kvm_queue_interrupt(vcpu, vector, false);

		break;

	case SVM_EXITINTINFO_TYPE_SOFT:

		kvm_queue_interrupt(vcpu, vector, true);

		break;

	default:

		break;

	}



}



static void svm_cancel_injection(struct kvm_vcpu *vcpu)