KVM: PPC: Implement alignment interrupt

Mac OS X has some applications - namely the Finder - that require alignment
interrupts to work properly. So we need to implement them.

But the spec for 970 and 750 also looks different. While 750 requires the
DSISR and DAR fields to reflect some instruction bits (DSISR) and the fault
address (DAR), the 970 declares this as an optional feature. So we need
to reconstruct DSISR and DAR manually.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/include/asm/kvm_book3s.h

@@ -131,6 +131,8 @@ extern void kvmppc_rmcall(ulong srr0, ulong srr1);
 extern void kvmppc_load_up_fpu(void);
 extern void kvmppc_load_up_altivec(void);
 extern void kvmppc_load_up_vsx(void);
+extern u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst);
+extern ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst);
 
 static inline struct kvmppc_vcpu_book3s *to_book3s(struct kvm_vcpu *vcpu)
 {

arch/powerpc/kvm/book3s.c

@@ -906,6 +906,16 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		}
 		break;
 	}
+	case BOOK3S_INTERRUPT_ALIGNMENT:
+		if (kvmppc_read_inst(vcpu) == EMULATE_DONE) {
+			to_book3s(vcpu)->dsisr = kvmppc_alignment_dsisr(vcpu,
+				vcpu->arch.last_inst);
+			vcpu->arch.dear = kvmppc_alignment_dar(vcpu,
+				vcpu->arch.last_inst);
+			kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
+		}
+		r = RESUME_GUEST;
+		break;
 	case BOOK3S_INTERRUPT_MACHINE_CHECK:
 	case BOOK3S_INTERRUPT_TRACE:
 		kvmppc_book3s_queue_irqprio(vcpu, exit_nr);

arch/powerpc/kvm/book3s_64_emulate.c

@@ -44,6 +44,11 @@
 /* DCBZ is actually 1014, but we patch it to 1010 so we get a trap */
 #define OP_31_XOP_DCBZ		1010
 
+#define OP_LFS			48
+#define OP_LFD			50
+#define OP_STFS			52
+#define OP_STFD			54
+
 #define SPRN_GQR0		912
 #define SPRN_GQR1		913
 #define SPRN_GQR2		914
@@ -474,3 +479,73 @@ int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
 	return emulated;
 }
 
+u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst)
+{
+	u32 dsisr = 0;
+
+	/*
+	 * This is what the spec says about DSISR bits (not mentioned = 0):
+	 *
+	 * 12:13		[DS]	Set to bits 30:31
+	 * 15:16		[X]	Set to bits 29:30
+	 * 17			[X]	Set to bit 25
+	 *			[D/DS]	Set to bit 5
+	 * 18:21		[X]	Set to bits 21:24
+	 *			[D/DS]	Set to bits 1:4
+	 * 22:26			Set to bits 6:10 (RT/RS/FRT/FRS)
+	 * 27:31			Set to bits 11:15 (RA)
+	 */
+
+	switch (get_op(inst)) {
+	/* D-form */
+	case OP_LFS:
+	case OP_LFD:
+	case OP_STFD:
+	case OP_STFS:
+		dsisr |= (inst >> 12) & 0x4000;	/* bit 17 */
+		dsisr |= (inst >> 17) & 0x3c00; /* bits 18:21 */
+		break;
+	/* X-form */
+	case 31:
+		dsisr |= (inst << 14) & 0x18000; /* bits 15:16 */
+		dsisr |= (inst << 8)  & 0x04000; /* bit 17 */
+		dsisr |= (inst << 3)  & 0x03c00; /* bits 18:21 */
+		break;
+	default:
+		printk(KERN_INFO "KVM: Unaligned instruction 0x%x\n", inst);
+		break;
+	}
+
+	dsisr |= (inst >> 16) & 0x03ff; /* bits 22:31 */
+
+	return dsisr;
+}
+
+ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst)
+{
+	ulong dar = 0;
+	ulong ra;
+
+	switch (get_op(inst)) {
+	case OP_LFS:
+	case OP_LFD:
+	case OP_STFD:
+	case OP_STFS:
+		ra = get_ra(inst);
+		if (ra)
+			dar = kvmppc_get_gpr(vcpu, ra);
+		dar += (s32)((s16)inst);
+		break;
+	case 31:
+		ra = get_ra(inst);
+		if (ra)
+			dar = kvmppc_get_gpr(vcpu, ra);
+		dar += kvmppc_get_gpr(vcpu, get_rb(inst));
+		break;
+	default:
+		printk(KERN_INFO "KVM: Unaligned instruction 0x%x\n", inst);
+		break;
+	}
+
+	return dar;
+}