Commit e390f4d6 authored by Liam Ni's avatar Liam Ni Committed by Paolo Bonzini
Browse files

KVM:x86: Clean up ModR/M "reg" initialization in reg op decoding 



Refactor decode_register_operand() to get the ModR/M register if and
only if the instruction uses a ModR/M encoding to make it more obvious
how the register operand is retrieved.

Signed-off-by: default avatarLiam Ni <zhiguangni01@gmail.com>
Link: https://lore.kernel.org/r/20220908141210.1375828-1-zhiguangni01@zhaoxin.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 02dfc44f

arch/x86/kvm/emulate.c

+4 −2
Original line number Diff line number Diff line
@@ -1137,9 +1137,11 @@ static int em_fnstsw(struct x86_emulate_ctxt *ctxt) 
static void decode_register_operand(struct x86_emulate_ctxt *ctxt,

				    struct operand *op)

{

	unsigned reg = ctxt->modrm_reg;

	unsigned int reg;



	if (!(ctxt->d & ModRM))

	if (ctxt->d & ModRM)

		reg = ctxt->modrm_reg;

	else

		reg = (ctxt->b & 7) | ((ctxt->rex_prefix & 1) << 3);



	if (ctxt->d & Sse) {