KVM: nSVM: inject exceptions via svm_check_nested_events

This allows exceptions injected by the emulator to be properly delivered
as vmexits.  The code also becomes simpler, because we can just let all
L0-intercepted exceptions go through the usual path.  In particular, our
emulation of the VMX #DB exit qualification is very much simplified,
because the vmexit injection path can use kvm_deliver_exception_payload
to update DR6.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.c

@@ -331,17 +331,8 @@ static void svm_queue_exception(struct kvm_vcpu *vcpu)
 	struct vcpu_svm *svm = to_svm(vcpu);
 	unsigned nr = vcpu->arch.exception.nr;
 	bool has_error_code = vcpu->arch.exception.has_error_code;
-	bool reinject = vcpu->arch.exception.injected;
 	u32 error_code = vcpu->arch.exception.error_code;
 
-	/*
-	 * If we are within a nested VM we'd better #VMEXIT and let the guest
-	 * handle the exception
-	 */
-	if (!reinject &&
-	    nested_svm_check_exception(svm, nr, has_error_code, error_code))
-		return;
-
 	kvm_deliver_exception_payload(&svm->vcpu);
 
 	if (nr == BP_VECTOR && !nrips) {