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KVM: x86: Share emulator's common register decoding code

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Remove all duplicate handling of register operands, including picking
the right register class and fetching it, by extracting a new function
that can be used for both REG and MODRM operands.

Centralize setting op->orig_val = op->val in fetch_register_operand()
as well.

No functional change intended.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Chang S. Bae <chang.seok.bae@intel.com>
Link: https://patch.msgid.link/20251114003633.60689-6-pbonzini@redhat.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Paolo Bonzini 2025-11-13 19:36:28 -05:00 committed by Sean Christopherson
parent 1a84b07aca
commit 7e11eec989
1 changed files with 17 additions and 32 deletions
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49
arch/x86/kvm/emulate.c
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@ -1026,6 +1026,7 @@ static void fetch_register_operand(struct operand *op)
op->val = *(u64 *)op->addr.reg;
break;
}
op->orig_val = op->val;
}
static int em_fninit(struct x86_emulate_ctxt *ctxt)
@ -1071,16 +1072,9 @@ static int em_fnstsw(struct x86_emulate_ctxt *ctxt)
return X86EMUL_CONTINUE;
}
static void decode_register_operand(struct x86_emulate_ctxt *ctxt,
struct operand *op)
static void __decode_register_operand(struct x86_emulate_ctxt *ctxt,
struct operand *op, int reg)
{
unsigned int reg;
if (ctxt->d & ModRM)
reg = ctxt->modrm_reg;
else
reg = (ctxt->b & 7) | ((ctxt->rex_prefix & 1) << 3);
if (ctxt->d & Sse) {
op->type = OP_XMM;
op->bytes = 16;
@ -1099,9 +1093,20 @@ static void decode_register_operand(struct x86_emulate_ctxt *ctxt,
op->type = OP_REG;
op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
op->addr.reg = decode_register(ctxt, reg, ctxt->d & ByteOp);
fetch_register_operand(op);
op->orig_val = op->val;
}
static void decode_register_operand(struct x86_emulate_ctxt *ctxt,
struct operand *op)
{
unsigned int reg;
if (ctxt->d & ModRM)
reg = ctxt->modrm_reg;
else
reg = (ctxt->b & 7) | ((ctxt->rex_prefix & 1) << 3);
__decode_register_operand(ctxt, op, reg);
}
static void adjust_modrm_seg(struct x86_emulate_ctxt *ctxt, int base_reg)
@ -1128,24 +1133,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
ctxt->modrm_seg = VCPU_SREG_DS;
if (ctxt->modrm_mod == 3 || (ctxt->d & NoMod)) {
op->type = OP_REG;
op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
op->addr.reg = decode_register(ctxt, ctxt->modrm_rm,
ctxt->d & ByteOp);
if (ctxt->d & Sse) {
op->type = OP_XMM;
op->bytes = 16;
op->addr.xmm = ctxt->modrm_rm;
kvm_read_sse_reg(ctxt->modrm_rm, &op->vec_val);
return rc;
}
if (ctxt->d & Mmx) {
op->type = OP_MM;
op->bytes = 8;
op->addr.mm = ctxt->modrm_rm & 7;
return rc;
}
fetch_register_operand(op);
__decode_register_operand(ctxt, op, ctxt->modrm_rm);
return rc;
}
@ -4619,14 +4607,12 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
op->addr.reg = reg_rmw(ctxt, VCPU_REGS_RAX);
fetch_register_operand(op);
op->orig_val = op->val;
break;
case OpAccLo:
op->type = OP_REG;
op->bytes = (ctxt->d & ByteOp) ? 2 : ctxt->op_bytes;
op->addr.reg = reg_rmw(ctxt, VCPU_REGS_RAX);
fetch_register_operand(op);
op->orig_val = op->val;
break;
case OpAccHi:
if (ctxt->d & ByteOp) {
@ -4637,7 +4623,6 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
op->bytes = ctxt->op_bytes;
op->addr.reg = reg_rmw(ctxt, VCPU_REGS_RDX);
fetch_register_operand(op);
op->orig_val = op->val;
break;
case OpDI:
op->type = OP_MEM;