KVM: PPC: Make PV mtmsrd L=1 work with r30 and r31

We had an arbitrary limitation in mtmsrd L=1 that kept us from using r30 and
r31 as input registers. Let's get rid of that and get more potential speedups!

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

1 files changed, 17 insertions, 4 deletions

diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index 10b681c092ed..48a033865410 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -158,6 +158,7 @@ static u32 *kvm_alloc(int len)
 
 extern u32 kvm_emulate_mtmsrd_branch_offs;
 extern u32 kvm_emulate_mtmsrd_reg_offs;
+extern u32 kvm_emulate_mtmsrd_orig_ins_offs;
 extern u32 kvm_emulate_mtmsrd_len;
 extern u32 kvm_emulate_mtmsrd[];
 
@@ -186,7 +187,21 @@ static void kvm_patch_ins_mtmsrd(u32 *inst, u32 rt)
         /* Modify the chunk to fit the invocation */
         memcpy(p, kvm_emulate_mtmsrd, kvm_emulate_mtmsrd_len * 4);
         p[kvm_emulate_mtmsrd_branch_offs] |= distance_end & KVM_INST_B_MASK;
-        p[kvm_emulate_mtmsrd_reg_offs] |= rt;
+        switch (get_rt(rt)) {
+        case 30:
+                kvm_patch_ins_ll(&p[kvm_emulate_mtmsrd_reg_offs],
+                                 magic_var(scratch2), KVM_RT_30);
+                break;
+        case 31:
+                kvm_patch_ins_ll(&p[kvm_emulate_mtmsrd_reg_offs],
+                                 magic_var(scratch1), KVM_RT_30);
+                break;
+        default:
+                p[kvm_emulate_mtmsrd_reg_offs] |= rt;
+                break;
+        }
+
+        p[kvm_emulate_mtmsrd_orig_ins_offs] = *inst;
         flush_icache_range((ulong)p, (ulong)p + kvm_emulate_mtmsrd_len * 4);
 
         /* Patch the invocation */
@@ -423,9 +438,7 @@ static void kvm_check_ins(u32 *inst, u32 features)
 
         /* Rewrites */
         case KVM_INST_MTMSRD_L1:
-                /* We use r30 and r31 during the hook */
-                if (get_rt(inst_rt) < 30)
-                        kvm_patch_ins_mtmsrd(inst, inst_rt);
+                kvm_patch_ins_mtmsrd(inst, inst_rt);
                 break;
         case KVM_INST_MTMSR:
         case KVM_INST_MTMSRD_L0: