[PATCH v2 05/13] x86/kvm/emulate: Introduce COP2W

Peter Zijlstra
2025-04-30T11:26:48Z

Replace the FASTOP2W instructions.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/kvm/emulate.c | 47 ++++++++++++++++++++++++++++-------------------
1 file changed, 28 insertions(+), 19 deletions(-)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -335,6 +335,15 @@ static int em_##op(struct x86_emulate_ct
ON64(case 8: COP_ASM2(op##q, rdx, rax); break;) \
COP_END

+/* 2-operand, word only (no byte op) */
+#define COP2W(op) \
+ COP_START(op) \
+ case 1: break; \
+ case 2: COP_ASM2(op##w, ax, dx); break; \
+ case 4: COP_ASM2(op##l, eax, edx); break; \
+ ON64(case 8: COP_ASM2(op##q, rax, rdx); break;) \
+ COP_END
+
/*
* fastop functions have a special calling convention:
*
@@ -1064,7 +1073,7 @@ FASTOP1SRC2EX(idiv, idiv_ex);
FASTOP3WCL(shld);
FASTOP3WCL(shrd);

-FASTOP2W(imul);
+COP2W(imul);

COP1(not);
COP1(neg);
@@ -1079,12 +1088,12 @@ FASTOP2CL(shl);
FASTOP2CL(shr);
FASTOP2CL(sar);

-FASTOP2W(bsf);
-FASTOP2W(bsr);
-FASTOP2W(bt);
-FASTOP2W(bts);
-FASTOP2W(btr);
-FASTOP2W(btc);
+COP2W(bsf);
+COP2W(bsr);
+COP2W(bt);
+COP2W(bts);
+COP2W(btr);
+COP2W(btc);

COP2R(cmp, cmp_r);

@@ -1093,7 +1102,7 @@ static int em_bsf_c(struct x86_emulate_c
/* If src is zero, do not writeback, but update flags */
if (ctxt->src.val == 0)
ctxt->dst.type = OP_NONE;
- return fastop(ctxt, em_bsf);
+ return em_bsf(ctxt);
}

static int em_bsr_c(struct x86_emulate_ctxt *ctxt)
@@ -1101,7 +1110,7 @@ static int em_bsr_c(struct x86_emulate_c
/* If src is zero, do not writeback, but update flags */
if (ctxt->src.val == 0)
ctxt->dst.type = OP_NONE;
- return fastop(ctxt, em_bsr);
+ return em_bsr(ctxt);
}

static __always_inline u8 test_cc(unsigned int condition, unsigned long flags)
@@ -3221,7 +3230,7 @@ static int em_xchg(struct x86_emulate_ct
static int em_imul_3op(struct x86_emulate_ctxt *ctxt)
{
ctxt->dst.val = ctxt->src2.val;
- return fastop(ctxt, em_imul);
+ return em_imul(ctxt);
}

static int em_cwd(struct x86_emulate_ctxt *ctxt)
@@ -4135,10 +4144,10 @@ static const struct group_dual group7 =

static const struct opcode group8[] = {
N, N, N, N,
- F(DstMem | SrcImmByte | NoWrite, em_bt),
- F(DstMem | SrcImmByte | Lock | PageTable, em_bts),
- F(DstMem | SrcImmByte | Lock, em_btr),
- F(DstMem | SrcImmByte | Lock | PageTable, em_btc),
+ I(DstMem | SrcImmByte | NoWrite, em_bt),
+ I(DstMem | SrcImmByte | Lock | PageTable, em_bts),
+ I(DstMem | SrcImmByte | Lock, em_btr),
+ I(DstMem | SrcImmByte | Lock | PageTable, em_btc),
};

/*
@@ -4459,27 +4468,27 @@ static const struct opcode twobyte_table
/* 0xA0 - 0xA7 */
I(Stack | Src2FS, em_push_sreg), I(Stack | Src2FS, em_pop_sreg),
II(ImplicitOps, em_cpuid, cpuid),
- F(DstMem | SrcReg | ModRM | BitOp | NoWrite, em_bt),
+ I(DstMem | SrcReg | ModRM | BitOp | NoWrite, em_bt),
F(DstMem | SrcReg | Src2ImmByte | ModRM, em_shld),
F(DstMem | SrcReg | Src2CL | ModRM, em_shld), N, N,
/* 0xA8 - 0xAF */
I(Stack | Src2GS, em_push_sreg), I(Stack | Src2GS, em_pop_sreg),
II(EmulateOnUD | ImplicitOps, em_rsm, rsm),
- F(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_bts),
+ I(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_bts),
F(DstMem | SrcReg | Src2ImmByte | ModRM, em_shrd),
F(DstMem | SrcReg | Src2CL | ModRM, em_shrd),
- GD(0, &group15), F(DstReg | SrcMem | ModRM, em_imul),
+ GD(0, &group15), I(DstReg | SrcMem | ModRM, em_imul),
/* 0xB0 - 0xB7 */
I2bv(DstMem | SrcReg | ModRM | Lock | PageTable | SrcWrite, em_cmpxchg),
I(DstReg | SrcMemFAddr | ModRM | Src2SS, em_lseg),
- F(DstMem | SrcReg | ModRM | BitOp | Lock, em_btr),
+ I(DstMem | SrcReg | ModRM | BitOp | Lock, em_btr),
I(DstReg | SrcMemFAddr | ModRM | Src2FS, em_lseg),
I(DstReg | SrcMemFAddr | ModRM | Src2GS, em_lseg),
D(DstReg | SrcMem8 | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov),
/* 0xB8 - 0xBF */
N, N,
G(BitOp, group8),
- F(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_btc),
+ I(DstMem | SrcReg | ModRM | BitOp | Lock | PageTable, em_btc),
I(DstReg | SrcMem | ModRM, em_bsf_c),
I(DstReg | SrcMem | ModRM, em_bsr_c),
D(DstReg | SrcMem8 | ModRM | Mov), D(DstReg | SrcMem16 | ModRM | Mov),