KVM: PPC: Emulator: clean up SPR reads and writes

When reading and writing SPRs, every SPR emulation piece had to read
or write the respective GPR the value was read from or stored in itself.

This approach is pretty prone to failure. What if we accidentally
implement mfspr emulation where we just do "break" and nothing else?
Suddenly we would get a random value in the return register - which is
always a bad idea.

So let's consolidate the generic code paths and only give the core
specific SPR handling code readily made variables to read/write from/to.

Functionally, this patch doesn't change anything, but it increases the
readability of the code and makes is less prone to bugs.

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

1 files changed, 66 insertions, 44 deletions

diff --git a/arch/powerpc/kvm/e500_emulate.c b/arch/powerpc/kvm/e500_emulate.c
index 9b2dcda71950..8b99e076dc81 100644
--- a/arch/powerpc/kvm/e500_emulate.c
+++ b/arch/powerpc/kvm/e500_emulate.c
@@ -140,11 +140,10 @@ int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
         return emulated;
 }
 
-int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
+int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
 {
         struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
         int emulated = EMULATE_DONE;
-        ulong spr_val = kvmppc_get_gpr(vcpu, rs);
 
         switch (sprn) {
 #ifndef CONFIG_KVM_BOOKE_HV
@@ -154,25 +153,32 @@ int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
         case SPRN_PID1:
                 if (spr_val != 0)
                         return EMULATE_FAIL;
-                vcpu_e500->pid[1] = spr_val; break;
+                vcpu_e500->pid[1] = spr_val;
+                break;
         case SPRN_PID2:
                 if (spr_val != 0)
                         return EMULATE_FAIL;
-                vcpu_e500->pid[2] = spr_val; break;
+                vcpu_e500->pid[2] = spr_val;
+                break;
         case SPRN_MAS0:
-                vcpu->arch.shared->mas0 = spr_val; break;
+                vcpu->arch.shared->mas0 = spr_val;
+                break;
         case SPRN_MAS1:
-                vcpu->arch.shared->mas1 = spr_val; break;
+                vcpu->arch.shared->mas1 = spr_val;
+                break;
         case SPRN_MAS2:
-                vcpu->arch.shared->mas2 = spr_val; break;
+                vcpu->arch.shared->mas2 = spr_val;
+                break;
         case SPRN_MAS3:
                 vcpu->arch.shared->mas7_3 &= ~(u64)0xffffffff;
                 vcpu->arch.shared->mas7_3 |= spr_val;
                 break;
         case SPRN_MAS4:
-                vcpu->arch.shared->mas4 = spr_val; break;
+                vcpu->arch.shared->mas4 = spr_val;
+                break;
         case SPRN_MAS6:
-                vcpu->arch.shared->mas6 = spr_val; break;
+                vcpu->arch.shared->mas6 = spr_val;
+                break;
         case SPRN_MAS7:
                 vcpu->arch.shared->mas7_3 &= (u64)0xffffffff;
                 vcpu->arch.shared->mas7_3 |= (u64)spr_val << 32;
@@ -183,11 +189,14 @@ int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
                 vcpu_e500->l1csr0 &= ~(L1CSR0_DCFI | L1CSR0_CLFC);
                 break;
         case SPRN_L1CSR1:
-                vcpu_e500->l1csr1 = spr_val; break;
+                vcpu_e500->l1csr1 = spr_val;
+                break;
         case SPRN_HID0:
-                vcpu_e500->hid0 = spr_val; break;
+                vcpu_e500->hid0 = spr_val;
+                break;
         case SPRN_HID1:
-                vcpu_e500->hid1 = spr_val; break;
+                vcpu_e500->hid1 = spr_val;
+                break;
 
         case SPRN_MMUCSR0:
                 emulated = kvmppc_e500_emul_mt_mmucsr0(vcpu_e500,
@@ -216,90 +225,103 @@ int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
                 break;
 #endif
         default:
-                emulated = kvmppc_booke_emulate_mtspr(vcpu, sprn, rs);
+                emulated = kvmppc_booke_emulate_mtspr(vcpu, sprn, spr_val);
         }
 
         return emulated;
 }
 
-int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
+int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
 {
         struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
         int emulated = EMULATE_DONE;
 
         switch (sprn) {
 #ifndef CONFIG_KVM_BOOKE_HV
-                unsigned long val;
-
         case SPRN_PID:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->pid[0]); break;
+                *spr_val = vcpu_e500->pid[0];
+                break;
         case SPRN_PID1:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->pid[1]); break;
+                *spr_val = vcpu_e500->pid[1];
+                break;
         case SPRN_PID2:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->pid[2]); break;
+                *spr_val = vcpu_e500->pid[2];
+                break;
         case SPRN_MAS0:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->mas0); break;
+                *spr_val = vcpu->arch.shared->mas0;
+                break;
         case SPRN_MAS1:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->mas1); break;
+                *spr_val = vcpu->arch.shared->mas1;
+                break;
         case SPRN_MAS2:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->mas2); break;
+                *spr_val = vcpu->arch.shared->mas2;
+                break;
         case SPRN_MAS3:
-                val = (u32)vcpu->arch.shared->mas7_3;
-                kvmppc_set_gpr(vcpu, rt, val);
+                *spr_val = (u32)vcpu->arch.shared->mas7_3;
                 break;
         case SPRN_MAS4:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->mas4); break;
+                *spr_val = vcpu->arch.shared->mas4;
+                break;
         case SPRN_MAS6:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->mas6); break;
+                *spr_val = vcpu->arch.shared->mas6;
+                break;
         case SPRN_MAS7:
-                val = vcpu->arch.shared->mas7_3 >> 32;
-                kvmppc_set_gpr(vcpu, rt, val);
+                *spr_val = vcpu->arch.shared->mas7_3 >> 32;
                 break;
 #endif
         case SPRN_TLB0CFG:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.tlbcfg[0]); break;
+                *spr_val = vcpu->arch.tlbcfg[0];
+                break;
         case SPRN_TLB1CFG:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.tlbcfg[1]); break;
+                *spr_val = vcpu->arch.tlbcfg[1];
+                break;
         case SPRN_L1CSR0:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->l1csr0); break;
+                *spr_val = vcpu_e500->l1csr0;
+                break;
         case SPRN_L1CSR1:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->l1csr1); break;
+                *spr_val = vcpu_e500->l1csr1;
+                break;
         case SPRN_HID0:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->hid0); break;
+                *spr_val = vcpu_e500->hid0;
+                break;
         case SPRN_HID1:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->hid1); break;
+                *spr_val = vcpu_e500->hid1;
+                break;
         case SPRN_SVR:
-                kvmppc_set_gpr(vcpu, rt, vcpu_e500->svr); break;
+                *spr_val = vcpu_e500->svr;
+                break;
 
         case SPRN_MMUCSR0:
-                kvmppc_set_gpr(vcpu, rt, 0); break;
+                *spr_val = 0;
+                break;
 
         case SPRN_MMUCFG:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.mmucfg); break;
+                *spr_val = vcpu->arch.mmucfg;
+                break;
 
         /* extra exceptions */
         case SPRN_IVOR32:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL]);
+                *spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_UNAVAIL];
                 break;
         case SPRN_IVOR33:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_FP_DATA]);
+                *spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_FP_DATA];
                 break;
         case SPRN_IVOR34:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_FP_ROUND]);
+                *spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_SPE_FP_ROUND];
                 break;
         case SPRN_IVOR35:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.ivor[BOOKE_IRQPRIO_PERFORMANCE_MONITOR]);
+                *spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_PERFORMANCE_MONITOR];
                 break;
 #ifdef CONFIG_KVM_BOOKE_HV
         case SPRN_IVOR36:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.ivor[BOOKE_IRQPRIO_DBELL]);
+                *spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_DBELL];
                 break;
         case SPRN_IVOR37:
-                kvmppc_set_gpr(vcpu, rt, vcpu->arch.ivor[BOOKE_IRQPRIO_DBELL_CRIT]);
+                *spr_val = vcpu->arch.ivor[BOOKE_IRQPRIO_DBELL_CRIT];
                 break;
 #endif
         default:
-                emulated = kvmppc_booke_emulate_mfspr(vcpu, sprn, rt);
+                emulated = kvmppc_booke_emulate_mfspr(vcpu, sprn, spr_val);
         }
 
         return emulated;