KVM: PPC: Emulator: clean up instruction parsing

Instructions on PPC are pretty similarly encoded. So instead of
every instruction emulation code decoding the instruction fields
itself, we can move that code to more generic places and rely on
the compiler to optimize the unused bits away.

This has 2 advantages. It makes the code smaller and it makes the
code less error prone, as the instruction fields are always
available, so accidental misusage is reduced.

Functionally, this patch doesn't change anything.

Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 38 insertions, 34 deletions

diff --git a/arch/powerpc/kvm/book3s_emulate.c b/arch/powerpc/kvm/book3s_emulate.c
index 135663a3e4fc..c023bcd253ff 100644
--- a/arch/powerpc/kvm/book3s_emulate.c
+++ b/arch/powerpc/kvm/book3s_emulate.c
@@ -87,6 +87,10 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
                            unsigned int inst, int *advance)
 {
 	int emulated = EMULATE_DONE;
+	int rt = get_rt(inst);
+	int rs = get_rs(inst);
+	int ra = get_ra(inst);
+	int rb = get_rb(inst);
 
 	switch (get_op(inst)) {
 	case 19:
@@ -106,21 +110,22 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 	case 31:
 		switch (get_xop(inst)) {
 		case OP_31_XOP_MFMSR:
-			kvmppc_set_gpr(vcpu, get_rt(inst),
-				       vcpu->arch.shared->msr);
+			kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->msr);
 			break;
 		case OP_31_XOP_MTMSRD:
 		{
-			ulong rs = kvmppc_get_gpr(vcpu, get_rs(inst));
+			ulong rs_val = kvmppc_get_gpr(vcpu, rs);
 			if (inst & 0x10000) {
-				vcpu->arch.shared->msr &= ~(MSR_RI | MSR_EE);
-				vcpu->arch.shared->msr |= rs & (MSR_RI | MSR_EE);
+				ulong new_msr = vcpu->arch.shared->msr;
+				new_msr &= ~(MSR_RI | MSR_EE);
+				new_msr |= rs_val & (MSR_RI | MSR_EE);
+				vcpu->arch.shared->msr = new_msr;
 			} else
-				kvmppc_set_msr(vcpu, rs);
+				kvmppc_set_msr(vcpu, rs_val);
 			break;
 		}
 		case OP_31_XOP_MTMSR:
-			kvmppc_set_msr(vcpu, kvmppc_get_gpr(vcpu, get_rs(inst)));
+			kvmppc_set_msr(vcpu, kvmppc_get_gpr(vcpu, rs));
 			break;
 		case OP_31_XOP_MFSR:
 		{
@@ -130,7 +135,7 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			if (vcpu->arch.mmu.mfsrin) {
 				u32 sr;
 				sr = vcpu->arch.mmu.mfsrin(vcpu, srnum);
-				kvmppc_set_gpr(vcpu, get_rt(inst), sr);
+				kvmppc_set_gpr(vcpu, rt, sr);
 			}
 			break;
 		}
@@ -138,29 +143,29 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		{
 			int srnum;
 
-			srnum = (kvmppc_get_gpr(vcpu, get_rb(inst)) >> 28) & 0xf;
+			srnum = (kvmppc_get_gpr(vcpu, rb) >> 28) & 0xf;
 			if (vcpu->arch.mmu.mfsrin) {
 				u32 sr;
 				sr = vcpu->arch.mmu.mfsrin(vcpu, srnum);
-				kvmppc_set_gpr(vcpu, get_rt(inst), sr);
+				kvmppc_set_gpr(vcpu, rt, sr);
 			}
 			break;
 		}
 		case OP_31_XOP_MTSR:
 			vcpu->arch.mmu.mtsrin(vcpu,
 				(inst >> 16) & 0xf,
-				kvmppc_get_gpr(vcpu, get_rs(inst)));
+				kvmppc_get_gpr(vcpu, rs));
 			break;
 		case OP_31_XOP_MTSRIN:
 			vcpu->arch.mmu.mtsrin(vcpu,
-				(kvmppc_get_gpr(vcpu, get_rb(inst)) >> 28) & 0xf,
-				kvmppc_get_gpr(vcpu, get_rs(inst)));
+				(kvmppc_get_gpr(vcpu, rb) >> 28) & 0xf,
+				kvmppc_get_gpr(vcpu, rs));
 			break;
 		case OP_31_XOP_TLBIE:
 		case OP_31_XOP_TLBIEL:
 		{
 			bool large = (inst & 0x00200000) ? true : false;
-			ulong addr = kvmppc_get_gpr(vcpu, get_rb(inst));
+			ulong addr = kvmppc_get_gpr(vcpu, rb);
 			vcpu->arch.mmu.tlbie(vcpu, addr, large);
 			break;
 		}
@@ -171,15 +176,15 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 				return EMULATE_FAIL;
 
 			vcpu->arch.mmu.slbmte(vcpu,
-					kvmppc_get_gpr(vcpu, get_rs(inst)),
-					kvmppc_get_gpr(vcpu, get_rb(inst)));
+					kvmppc_get_gpr(vcpu, rs),
+					kvmppc_get_gpr(vcpu, rb));
 			break;
 		case OP_31_XOP_SLBIE:
 			if (!vcpu->arch.mmu.slbie)
 				return EMULATE_FAIL;
 
 			vcpu->arch.mmu.slbie(vcpu,
-					kvmppc_get_gpr(vcpu, get_rb(inst)));
+					kvmppc_get_gpr(vcpu, rb));
 			break;
 		case OP_31_XOP_SLBIA:
 			if (!vcpu->arch.mmu.slbia)
@@ -191,22 +196,22 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			if (!vcpu->arch.mmu.slbmfee) {
 				emulated = EMULATE_FAIL;
 			} else {
-				ulong t, rb;
+				ulong t, rb_val;
 
-				rb = kvmppc_get_gpr(vcpu, get_rb(inst));
-				t = vcpu->arch.mmu.slbmfee(vcpu, rb);
-				kvmppc_set_gpr(vcpu, get_rt(inst), t);
+				rb_val = kvmppc_get_gpr(vcpu, rb);
+				t = vcpu->arch.mmu.slbmfee(vcpu, rb_val);
+				kvmppc_set_gpr(vcpu, rt, t);
 			}
 			break;
 		case OP_31_XOP_SLBMFEV:
 			if (!vcpu->arch.mmu.slbmfev) {
 				emulated = EMULATE_FAIL;
 			} else {
-				ulong t, rb;
+				ulong t, rb_val;
 
-				rb = kvmppc_get_gpr(vcpu, get_rb(inst));
-				t = vcpu->arch.mmu.slbmfev(vcpu, rb);
-				kvmppc_set_gpr(vcpu, get_rt(inst), t);
+				rb_val = kvmppc_get_gpr(vcpu, rb);
+				t = vcpu->arch.mmu.slbmfev(vcpu, rb_val);
+				kvmppc_set_gpr(vcpu, rt, t);
 			}
 			break;
 		case OP_31_XOP_DCBA:
@@ -214,17 +219,17 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
 			break;
 		case OP_31_XOP_DCBZ:
 		{
-			ulong rb = kvmppc_get_gpr(vcpu, get_rb(inst));
-			ulong ra = 0;
+			ulong rb_val = kvmppc_get_gpr(vcpu, rb);
+			ulong ra_val = 0;
 			ulong addr, vaddr;
 			u32 zeros[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
 			u32 dsisr;
 			int r;
 
-			if (get_ra(inst))
-				ra = kvmppc_get_gpr(vcpu, get_ra(inst));
+			if (ra)
+				ra_val = kvmppc_get_gpr(vcpu, ra);
 
-			addr = (ra + rb) & ~31ULL;
+			addr = (ra_val + rb_val) & ~31ULL;
 			if (!(vcpu->arch.shared->msr & MSR_SF))
 				addr &= 0xffffffff;
 			vaddr = addr;
@@ -565,23 +570,22 @@ u32 kvmppc_alignment_dsisr(struct kvm_vcpu *vcpu, unsigned int inst)
 ulong kvmppc_alignment_dar(struct kvm_vcpu *vcpu, unsigned int inst)
 {
 	ulong dar = 0;
-	ulong ra;
+	ulong ra = get_ra(inst);
+	ulong rb = get_rb(inst);
 
 	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));
+		dar += kvmppc_get_gpr(vcpu, rb);
 		break;
 	default:
 		printk(KERN_INFO "KVM: Unaligned instruction 0x%x\n", inst);