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Subject[RFC PATCH v2 3/6] KVM: emulate: cleanup decode_rm
Date
Remove the if conditional - that will help us avoid
an "else initialize to 0" Also, rearrange operators
for slightly better code.

Signed-off-by: Bandan Das <bsd@redhat.com>
---
arch/x86/kvm/emulate.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a6d9892..9cbaba2 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1064,19 +1064,17 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
struct operand *op)
{
u8 sib;
- int index_reg = 0, base_reg = 0, scale;
+ int index_reg, base_reg, scale;
int rc = X86EMUL_CONTINUE;
ulong modrm_ea = 0;

- if (ctxt->rex_prefix) {
- ctxt->modrm_reg = (ctxt->rex_prefix & 4) << 1; /* REX.R */
- index_reg = (ctxt->rex_prefix & 2) << 2; /* REX.X */
- ctxt->modrm_rm = base_reg = (ctxt->rex_prefix & 1) << 3; /* REG.B */
- }
+ index_reg = (ctxt->rex_prefix << 2) & 8; /* REX.X */
+ base_reg = (ctxt->rex_prefix << 3) & 8; /* REG.B */

- ctxt->modrm_mod |= (ctxt->modrm & 0xc0) >> 6;
- ctxt->modrm_reg |= (ctxt->modrm & 0x38) >> 3;
- ctxt->modrm_rm |= (ctxt->modrm & 0x07);
+ ctxt->modrm_mod = (ctxt->modrm & 0xc0) >> 6;
+ ctxt->modrm_reg = ((ctxt->rex_prefix << 1) & 8) | /* REX.R */
+ ((ctxt->modrm & 0x38) >> 3);
+ ctxt->modrm_rm = base_reg | (ctxt->modrm & 0x07);
ctxt->modrm_seg = VCPU_SREG_DS;

if (ctxt->modrm_mod == 3) {
--
1.8.3.1


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