Commit 684c0422 authored by Oliver Upton's avatar Oliver Upton Committed by Paolo Bonzini
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KVM: nVMX: Handle pending #DB when injecting INIT VM-exit 



SDM 27.3.4 states that the 'pending debug exceptions' VMCS field will
be populated if a VM-exit caused by an INIT signal takes priority over a
debug-trap. Emulate this behavior when synthesizing an INIT signal
VM-exit into L1.

Fixes: 4b9852f4 ("KVM: x86: Fix INIT signal handling in various CPU states")
Signed-off-by: default avatarOliver Upton <oupton@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 307f1cfa

arch/x86/kvm/vmx/nested.c

+28 −0
Original line number Diff line number Diff line
@@ -3575,6 +3575,33 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu, 
	nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, intr_info, exit_qual);

}



/*

 * Returns true if a debug trap is pending delivery.

 *

 * In KVM, debug traps bear an exception payload. As such, the class of a #DB

 * exception may be inferred from the presence of an exception payload.

 */

static inline bool vmx_pending_dbg_trap(struct kvm_vcpu *vcpu)

{

	return vcpu->arch.exception.pending &&

			vcpu->arch.exception.nr == DB_VECTOR &&

			vcpu->arch.exception.payload;

}



/*

 * Certain VM-exits set the 'pending debug exceptions' field to indicate a

 * recognized #DB (data or single-step) that has yet to be delivered. Since KVM

 * represents these debug traps with a payload that is said to be compatible

 * with the 'pending debug exceptions' field, write the payload to the VMCS

 * field if a VM-exit is delivered before the debug trap.

 */

static void nested_vmx_update_pending_dbg(struct kvm_vcpu *vcpu)

{

	if (vmx_pending_dbg_trap(vcpu))

		vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS,

			    vcpu->arch.exception.payload);

}



static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)

{

	struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -3587,6 +3614,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr) 
		test_bit(KVM_APIC_INIT, &apic->pending_events)) {

		if (block_nested_events)

			return -EBUSY;

		nested_vmx_update_pending_dbg(vcpu);

		clear_bit(KVM_APIC_INIT, &apic->pending_events);

		nested_vmx_vmexit(vcpu, EXIT_REASON_INIT_SIGNAL, 0, 0);

		return 0;