From 4e62417bf317504c0b85e0d7abd236f334f54eaf Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Wed, 17 Oct 2007 19:30:41 +0200 Subject: [PATCH] KVM: x86 emulator: fix access registers for instructions with ModR/M byte and Mod = 3 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 Signed-off-by: Avi Kivity --- drivers/kvm/x86_emulate.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c index 0a8696d9b8..a6ace302e0 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); -- 2.39.5