KVM: PPC: Combine extension interrupt handlers

When we for example get an Altivec interrupt, but our guest doesn't support
altivec, we need to inject a program interrupt, not an altivec interrupt.

The same goes for paired singles. When an altivec interrupt arrives, we're
pretty sure we need to emulate the instruction because it's a paired single
operation.

So let's make all the ext handlers aware that they need to jump to the
program interrupt handler when an extension interrupt arrives that
was not supposed to arrive for the guest CPU.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/kvm/book3s.c

@@ -37,6 +37,8 @@
 /* #define DEBUG_EXT */
 
 static void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr);
+static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
+			     ulong msr);
 
 struct kvm_stats_debugfs_item debugfs_entries[] = {
 	{ "exits",       VCPU_STAT(sum_exits) },
@@ -629,6 +631,30 @@ static void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr)
 	kvmppc_recalc_shadow_msr(vcpu);
 }
 
+static int kvmppc_check_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr)
+{
+	ulong srr0 = vcpu->arch.pc;
+	int ret;
+
+	/* Need to do paired single emulation? */
+	if (!(vcpu->arch.hflags & BOOK3S_HFLAG_PAIRED_SINGLE))
+		return EMULATE_DONE;
+
+	/* Read out the instruction */
+	ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &vcpu->arch.last_inst, false);
+	if (ret == -ENOENT) {
+		vcpu->arch.msr = kvmppc_set_field(vcpu->arch.msr, 33, 33, 1);
+		vcpu->arch.msr = kvmppc_set_field(vcpu->arch.msr, 34, 36, 0);
+		vcpu->arch.msr = kvmppc_set_field(vcpu->arch.msr, 42, 47, 0);
+		kvmppc_book3s_queue_irqprio(vcpu, BOOK3S_INTERRUPT_INST_STORAGE);
+	} else if(ret == EMULATE_DONE) {
+		/* Need to emulate */
+		return EMULATE_FAIL;
+	}
+
+	return EMULATE_AGAIN;
+}
+
 /* Handle external providers (FPU, Altivec, VSX) */
 static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
 			     ulong msr)
@@ -773,6 +799,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		enum emulation_result er;
 		ulong flags;
 
+program_interrupt:
 		flags = vcpu->arch.shadow_srr1 & 0x1f0000ull;
 
 		if (vcpu->arch.msr & MSR_PR) {
@@ -816,14 +843,32 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		r = RESUME_GUEST;
 		break;
 	case BOOK3S_INTERRUPT_FP_UNAVAIL:
-		r = kvmppc_handle_ext(vcpu, exit_nr, MSR_FP);
-		break;
 	case BOOK3S_INTERRUPT_ALTIVEC:
-		r = kvmppc_handle_ext(vcpu, exit_nr, MSR_VEC);
-		break;
 	case BOOK3S_INTERRUPT_VSX:
-		r = kvmppc_handle_ext(vcpu, exit_nr, MSR_VSX);
+	{
+		int ext_msr = 0;
+
+		switch (exit_nr) {
+		case BOOK3S_INTERRUPT_FP_UNAVAIL: ext_msr = MSR_FP;  break;
+		case BOOK3S_INTERRUPT_ALTIVEC:    ext_msr = MSR_VEC; break;
+		case BOOK3S_INTERRUPT_VSX:        ext_msr = MSR_VSX; break;
+		}
+
+		switch (kvmppc_check_ext(vcpu, exit_nr)) {
+		case EMULATE_DONE:
+			/* everything ok - let's enable the ext */
+			r = kvmppc_handle_ext(vcpu, exit_nr, ext_msr);
+			break;
+		case EMULATE_FAIL:
+			/* we need to emulate this instruction */
+			goto program_interrupt;
+			break;
+		default:
+			/* nothing to worry about - go again */
+			break;
+		}
 		break;
+	}
 	case BOOK3S_INTERRUPT_MACHINE_CHECK:
 	case BOOK3S_INTERRUPT_TRACE:
 		kvmppc_book3s_queue_irqprio(vcpu, exit_nr);