KVM: x86 emulator: Make emulate_pop() a little more generic

Allow emulate_pop() to read into arbitrary memory rather than just the
source operand.  Needed for complicated instructions like far returns.

Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 6 insertions, 9 deletions

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 54fb09889a80..94459f313f12 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -1136,18 +1136,19 @@ static inline void emulate_push(struct x86_emulate_ctxt *ctxt)
 }
 
 static int emulate_pop(struct x86_emulate_ctxt *ctxt,
-                       struct x86_emulate_ops *ops)
+                       struct x86_emulate_ops *ops,
+                       void *dest, int len)
 {
         struct decode_cache *c = &ctxt->decode;
         int rc;
 
         rc = ops->read_emulated(register_address(c, ss_base(ctxt),
                                                  c->regs[VCPU_REGS_RSP]),
-                                &c->src.val, c->src.bytes, ctxt->vcpu);
+                                dest, len, ctxt->vcpu);
         if (rc != 0)
                 return rc;
 
-        register_address_increment(c, &c->regs[VCPU_REGS_RSP], c->src.bytes);
+        register_address_increment(c, &c->regs[VCPU_REGS_RSP], len);
         return rc;
 }
 
@@ -1157,11 +1158,9 @@ static inline int emulate_grp1a(struct x86_emulate_ctxt *ctxt,
         struct decode_cache *c = &ctxt->decode;
         int rc;
 
-        c->src.bytes = c->dst.bytes;
-        rc = emulate_pop(ctxt, ops);
+        rc = emulate_pop(ctxt, ops, &c->dst.val, c->dst.bytes);
         if (rc != 0)
                 return rc;
-        c->dst.val = c->src.val;
         return 0;
 }
 
@@ -1467,11 +1466,9 @@ special_insn:
                 break;
         case 0x58 ... 0x5f: /* pop reg */
         pop_instruction:
-                c->src.bytes = c->op_bytes;
-                rc = emulate_pop(ctxt, ops);
+                rc = emulate_pop(ctxt, ops, &c->dst.val, c->op_bytes);
                 if (rc != 0)
                         goto done;
-                c->dst.val = c->src.val;
                 break;
         case 0x63:              /* movsxd */
                 if (ctxt->mode != X86EMUL_MODE_PROT64)