[PATCH 08/11] KVM: x86 emulator: fix access registers for instructions with ModR/M byte and Mod = 3

Avi Kivity
2007-10-21T11:10:06Z

From: Aurelien Jarno <aurelien@aurel32.net>

The patch belows changes the access type to register from memory for
instructions that are declared as SrcMem or DstMem, but have a
ModR/M byte with Mod = 3.

It fixes (at least) the lmsw and smsw instructions on an AMD64 CPU,
which are needed for FreeBSD.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
drivers/kvm/x86_emulate.c | 16 ++++++++++++++++
1 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 0a8696d..a6ace30 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -825,6 +825,14 @@ done_prefixes:
if (twobyte && b == 0x01 && modrm_reg == 7)
break;
srcmem_common:
+ /*
+ * For instructions with a ModR/M byte, switch to register
+ * access if Mod = 3.
+ */
+ if ((d & ModRM) && modrm_mod == 3) {
+ src.type = OP_REG;
+ break;
+ }
src.type = OP_MEM;
src.ptr = (unsigned long *)cr2;
src.val = 0;
@@ -893,6 +901,14 @@ done_prefixes:
dst.ptr = (unsigned long *)cr2;
dst.bytes = (d & ByteOp) ? 1 : op_bytes;
dst.val = 0;
+ /*
+ * For instructions with a ModR/M byte, switch to register
+ * access if Mod = 3.
+ */
+ if ((d & ModRM) && modrm_mod == 3) {
+ dst.type = OP_REG;
+ break;
+ }
if (d & BitOp) {
unsigned long mask = ~(dst.bytes * 8 - 1);

--
1.5.3