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, 4 insertions, 67 deletions

diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index a27d4dc3b4a..f63b5cbd822 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -148,11 +148,10 @@ u32 kvmppc_get_dec(struct kvm_vcpu *vcpu, u64 tb)
 int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {
 	u32 inst = kvmppc_get_last_inst(vcpu);
-	int ra;
-	int rb;
-	int rs;
-	int rt;
-	int sprn;
+	int ra = get_ra(inst);
+	int rs = get_rs(inst);
+	int rt = get_rt(inst);
+	int sprn = get_sprn(inst);
 	enum emulation_result emulated = EMULATE_DONE;
 	int advance = 1;
 
@@ -189,43 +188,31 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 			advance = 0;
 			break;
 		case OP_31_XOP_LWZX:
-			rt = get_rt(inst);
 			emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
 			break;
 
 		case OP_31_XOP_LBZX:
-			rt = get_rt(inst);
 			emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
 			break;
 
 		case OP_31_XOP_LBZUX:
-			rt = get_rt(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
 			kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
 			break;
 
 		case OP_31_XOP_STWX:
-			rs = get_rs(inst);
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               4, 1);
 			break;
 
 		case OP_31_XOP_STBX:
-			rs = get_rs(inst);
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               1, 1);
 			break;
 
 		case OP_31_XOP_STBUX:
-			rs = get_rs(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               1, 1);
@@ -233,28 +220,19 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 			break;
 
 		case OP_31_XOP_LHAX:
-			rt = get_rt(inst);
 			emulated = kvmppc_handle_loads(run, vcpu, rt, 2, 1);
 			break;
 
 		case OP_31_XOP_LHZX:
-			rt = get_rt(inst);
 			emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
 			break;
 
 		case OP_31_XOP_LHZUX:
-			rt = get_rt(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
 			kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
 			break;
 
 		case OP_31_XOP_MFSPR:
-			sprn = get_sprn(inst);
-			rt = get_rt(inst);
-
 			switch (sprn) {
 			case SPRN_SRR0:
 				kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->srr0);
@@ -310,20 +288,12 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 			break;
 
 		case OP_31_XOP_STHX:
-			rs = get_rs(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               2, 1);
 			break;
 
 		case OP_31_XOP_STHUX:
-			rs = get_rs(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               2, 1);
@@ -331,8 +301,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 			break;
 
 		case OP_31_XOP_MTSPR:
-			sprn = get_sprn(inst);
-			rs = get_rs(inst);
 			switch (sprn) {
 			case SPRN_SRR0:
 				vcpu->arch.shared->srr0 = kvmppc_get_gpr(vcpu, rs);
@@ -384,7 +352,6 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 			break;
 
 		case OP_31_XOP_LWBRX:
-			rt = get_rt(inst);
 			emulated = kvmppc_handle_load(run, vcpu, rt, 4, 0);
 			break;
 
@@ -392,25 +359,16 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 			break;
 
 		case OP_31_XOP_STWBRX:
-			rs = get_rs(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               4, 0);
 			break;
 
 		case OP_31_XOP_LHBRX:
-			rt = get_rt(inst);
 			emulated = kvmppc_handle_load(run, vcpu, rt, 2, 0);
 			break;
 
 		case OP_31_XOP_STHBRX:
-			rs = get_rs(inst);
-			ra = get_ra(inst);
-			rb = get_rb(inst);
-
 			emulated = kvmppc_handle_store(run, vcpu,
 						       kvmppc_get_gpr(vcpu, rs),
 			                               2, 0);
@@ -423,39 +381,30 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 		break;
 
 	case OP_LWZ:
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
 		break;
 
 	case OP_LWZU:
-		ra = get_ra(inst);
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_load(run, vcpu, rt, 4, 1);
 		kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
 		break;
 
 	case OP_LBZ:
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
 		break;
 
 	case OP_LBZU:
-		ra = get_ra(inst);
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_load(run, vcpu, rt, 1, 1);
 		kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
 		break;
 
 	case OP_STW:
-		rs = get_rs(inst);
 		emulated = kvmppc_handle_store(run, vcpu,
 					       kvmppc_get_gpr(vcpu, rs),
 		                               4, 1);
 		break;
 
 	case OP_STWU:
-		ra = get_ra(inst);
-		rs = get_rs(inst);
 		emulated = kvmppc_handle_store(run, vcpu,
 					       kvmppc_get_gpr(vcpu, rs),
 		                               4, 1);
@@ -463,15 +412,12 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 		break;
 
 	case OP_STB:
-		rs = get_rs(inst);
 		emulated = kvmppc_handle_store(run, vcpu,
 					       kvmppc_get_gpr(vcpu, rs),
 		                               1, 1);
 		break;
 
 	case OP_STBU:
-		ra = get_ra(inst);
-		rs = get_rs(inst);
 		emulated = kvmppc_handle_store(run, vcpu,
 					       kvmppc_get_gpr(vcpu, rs),
 		                               1, 1);
@@ -479,39 +425,30 @@ int kvmppc_emulate_instruction(struct kvm_run *run, struct kvm_vcpu *vcpu)
 		break;
 
 	case OP_LHZ:
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
 		break;
 
 	case OP_LHZU:
-		ra = get_ra(inst);
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_load(run, vcpu, rt, 2, 1);
 		kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
 		break;
 
 	case OP_LHA:
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_loads(run, vcpu, rt, 2, 1);
 		break;
 
 	case OP_LHAU:
-		ra = get_ra(inst);
-		rt = get_rt(inst);
 		emulated = kvmppc_handle_loads(run, vcpu, rt, 2, 1);
 		kvmppc_set_gpr(vcpu, ra, vcpu->arch.vaddr_accessed);
 		break;
 
 	case OP_STH:
-		rs = get_rs(inst);
 		emulated = kvmppc_handle_store(run, vcpu,
 					       kvmppc_get_gpr(vcpu, rs),
 		                               2, 1);
 		break;
 
 	case OP_STHU:
-		ra = get_ra(inst);
-		rs = get_rs(inst);
 		emulated = kvmppc_handle_store(run, vcpu,
 					       kvmppc_get_gpr(vcpu, rs),
 		                               2, 1);