arm64: KVM: Inject a Virtual SError if it was pending

If we have caught an SError whilst exiting, we've tagged the
exit code with the pending information. In that case, let's
re-inject the error into the guest, after having adjusted
the PC if required.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm64/kvm/handle_exit.c

@@ -170,6 +170,26 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 {
 	exit_handle_fn exit_handler;
 
+	if (ARM_SERROR_PENDING(exception_index)) {
+		u8 hsr_ec = ESR_ELx_EC(kvm_vcpu_get_hsr(vcpu));
+
+		/*
+		 * HVC/SMC already have an adjusted PC, which we need
+		 * to correct in order to return to after having
+		 * injected the SError.
+		 */
+		if (hsr_ec == ESR_ELx_EC_HVC32 || hsr_ec == ESR_ELx_EC_HVC64 ||
+		    hsr_ec == ESR_ELx_EC_SMC32 || hsr_ec == ESR_ELx_EC_SMC64) {
+			u32 adj =  kvm_vcpu_trap_il_is32bit(vcpu) ? 4 : 2;
+			*vcpu_pc(vcpu) -= adj;
+		}
+
+		kvm_inject_vabt(vcpu);
+		return 1;
+	}
+
+	exception_index = ARM_EXCEPTION_CODE(exception_index);
+
 	switch (exception_index) {
 	case ARM_EXCEPTION_IRQ:
 		return 1;