KVM: x86 emulator: introduce Op3264 for mov cr and mov dr instructions

The operands for these instructions are 32 bits or 64 bits, depending on
long mode, and ignoring REX prefixes, or the operand size prefix.

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

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a832019138f38eb03c1c38e7049fe4081fac2590..b7adfcc2f74f0393f367241bd67e7fe22fa8f44e 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -83,6 +83,7 @@
 #define Group       (1<<14)     /* Bits 3:5 of modrm byte extend opcode */
 #define GroupDual   (1<<15)     /* Alternate decoding of mod == 3 */
 /* Misc flags */
+#define Op3264      (1<<24) /* Operand is 64b in long mode, 32b otherwise */
 #define Undefined   (1<<25) /* No Such Instruction */
 #define Lock        (1<<26) /* lock prefix is allowed for the instruction */
 #define Priv        (1<<27) /* instruction generates #GP if current CPL != 0 */
@@ -2406,6 +2407,13 @@ done_prefixes:
        if (mode == X86EMUL_MODE_PROT64 && (c->d & Stack))
                c->op_bytes = 8;
 
+       if (c->d & Op3264) {
+               if (mode == X86EMUL_MODE_PROT64)
+                       c->op_bytes = 8;
+               else
+                       c->op_bytes = 4;
+       }
+
        /* ModRM and SIB bytes. */
        if (c->d & ModRM) {
                rc = decode_modrm(ctxt, ops);