KVM: x86 emulator: populate OP_MEM operand during decoding.

All struct operand fields are initialized during decoding for all
operand types except OP_MEM, but there is no reason for that. Move
OP_MEM operand initialization into decoding stage for consistency.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8225ec2..0eed683 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1057,6 +1057,10 @@ done_prefixes:
 
        if (c->ad_bytes != 8)
                c->modrm_ea = (u32)c->modrm_ea;
+
+       if (c->rip_relative)
+               c->modrm_ea += c->eip;
+
        /*
         * Decode and fetch the source operand: register, memory
         * or immediate.
@@ -1091,6 +1095,8 @@ done_prefixes:
                        break;
                }
                c->src.type = OP_MEM;
+               c->src.ptr = (unsigned long *)c->modrm_ea;
+               c->src.val = 0;
                break;
        case SrcImm:
        case SrcImmU:
@@ -1169,8 +1175,10 @@ done_prefixes:
                c->src2.val = 1;
                break;
        case Src2Mem16:
-               c->src2.bytes = 2;
                c->src2.type = OP_MEM;
+               c->src2.bytes = 2;
+               c->src2.ptr = (unsigned long *)(c->modrm_ea + c->src.bytes);
+               c->src2.val = 0;
                break;
        }
 
@@ -1192,6 +1200,15 @@ done_prefixes:
                        break;
                }
                c->dst.type = OP_MEM;
+               c->dst.ptr = (unsigned long *)c->modrm_ea;
+               c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
+               c->dst.val = 0;
+               if (c->d & BitOp) {
+                       unsigned long mask = ~(c->dst.bytes * 8 - 1);
+
+                       c->dst.ptr = (void *)c->dst.ptr +
+                                                  (c->src.val & mask) / 8;
+               }
                break;
        case DstAcc:
                c->dst.type = OP_REG;
@@ -1215,9 +1232,6 @@ done_prefixes:
                break;
        }
 
-       if (c->rip_relative)
-               c->modrm_ea += c->eip;
-
 done:
        return (rc == X86EMUL_UNHANDLEABLE) ? -1 : 0;
 }
@@ -1638,14 +1652,13 @@ static inline int emulate_grp45(struct x86_emulate_ctxt *ctxt,
 }
 
 static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
-                              struct x86_emulate_ops *ops,
-                              unsigned long memop)
+                              struct x86_emulate_ops *ops)
 {
        struct decode_cache *c = &ctxt->decode;
        u64 old, new;
        int rc;
 
-       rc = ops->read_emulated(memop, &old, 8, ctxt->vcpu);
+       rc = ops->read_emulated(c->modrm_ea, &old, 8, ctxt->vcpu);
        if (rc != X86EMUL_CONTINUE)
                return rc;
 
@@ -1660,7 +1673,7 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
                new = ((u64)c->regs[VCPU_REGS_RCX] << 32) |
                       (u32) c->regs[VCPU_REGS_RBX];
 
-               rc = ops->cmpxchg_emulated(memop, &old, &new, 8, ctxt->vcpu);
+               rc = ops->cmpxchg_emulated(c->modrm_ea, &old, &new, 8, ctxt->vcpu);
                if (rc != X86EMUL_CONTINUE)
                        return rc;
                ctxt->eflags |= EFLG_ZF;
@@ -2382,7 +2395,6 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt,
 int
 x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 {
-       unsigned long memop = 0;
        u64 msr_data;
        unsigned long saved_eip = 0;
        struct decode_cache *c = &ctxt->decode;
@@ -2417,9 +2429,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                goto done;
        }
 
-       if (((c->d & ModRM) && (c->modrm_mod != 3)) || (c->d & MemAbs))
-               memop = c->modrm_ea;
-
        if (c->rep_prefix && (c->d & String)) {
                /* All REP prefixes have the same first termination condition */
                if (address_mask(c, c->regs[VCPU_REGS_RCX]) == 0) {
@@ -2451,8 +2460,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
        }
 
        if (c->src.type == OP_MEM) {
-               c->src.ptr = (unsigned long *)memop;
-               c->src.val = 0;
                rc = ops->read_emulated((unsigned long)c->src.ptr,
                                        &c->src.val,
                                        c->src.bytes,
@@ -2463,8 +2470,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
        }
 
        if (c->src2.type == OP_MEM) {
-               c->src2.ptr = (unsigned long *)(memop + c->src.bytes);
-               c->src2.val = 0;
                rc = ops->read_emulated((unsigned long)c->src2.ptr,
                                        &c->src2.val,
                                        c->src2.bytes,
@@ -2477,25 +2482,12 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
                goto special_insn;
 
 
-       if (c->dst.type == OP_MEM) {
-               c->dst.ptr = (unsigned long *)memop;
-               c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-               c->dst.val = 0;
-               if (c->d & BitOp) {
-                       unsigned long mask = ~(c->dst.bytes * 8 - 1);
-
-                       c->dst.ptr = (void *)c->dst.ptr +
-                                                  (c->src.val & mask) / 8;
-               }
-               if (!(c->d & Mov)) {
-                       /* optimisation - avoid slow emulated read */
-                       rc = ops->read_emulated((unsigned long)c->dst.ptr,
-                                               &c->dst.val,
-                                               c->dst.bytes,
-                                               ctxt->vcpu);
-                       if (rc != X86EMUL_CONTINUE)
-                               goto done;
-               }
+       if ((c->dst.type == OP_MEM) && !(c->d & Mov)) {
+               /* optimisation - avoid slow emulated read if Mov */
+               rc = ops->read_emulated((unsigned long)c->dst.ptr, &c->dst.val,
+                                       c->dst.bytes, ctxt->vcpu);
+               if (rc != X86EMUL_CONTINUE)
+                       goto done;
        }
        c->dst.orig_val = c->dst.val;
 
@@ -3062,7 +3054,7 @@ twobyte_insn:
                        kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
                        goto done;
                case 7: /* invlpg*/
-                       emulate_invlpg(ctxt->vcpu, memop);
+                       emulate_invlpg(ctxt->vcpu, c->modrm_ea);
                        /* Disable writeback. */
                        c->dst.type = OP_NONE;
                        break;
@@ -3263,7 +3255,7 @@ twobyte_insn:
                                                        (u64) c->src.val;
                break;
        case 0xc7:              /* Grp9 (cmpxchg8b) */
-               rc = emulate_grp9(ctxt, ops, memop);
+               rc = emulate_grp9(ctxt, ops);
                if (rc != X86EMUL_CONTINUE)
                        goto done;
                c->dst.type = OP_NONE;