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Commit 573e80fe authored by Bandan Das's avatar Bandan Das Committed by Paolo Bonzini
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KVM: emulate: rework seg_override 



x86_decode_insn already sets a default for seg_override,
so remove it from the zeroed area. Also replace set/get functions
with direct access to the field.

Signed-off-by: default avatarBandan Das <bsd@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c44b4c6a

arch/x86/include/asm/kvm_emulate.h

+1 −2
Original line number Diff line number Diff line
@@ -295,12 +295,10 @@ struct x86_emulate_ctxt { 
	struct operand dst;

	int (*execute)(struct x86_emulate_ctxt *ctxt);

	int (*check_perm)(struct x86_emulate_ctxt *ctxt);

	bool has_seg_override;

	bool rip_relative;

	u8 rex_prefix;

	u8 lock_prefix;

	u8 rep_prefix;

	u8 seg_override;

	/* bitmaps of registers in _regs[] that can be read */

	u32 regs_valid;

	/* bitmaps of registers in _regs[] that have been written */
@@ -311,6 +309,7 @@ struct x86_emulate_ctxt { 
	u8 modrm_reg;

	u8 modrm_rm;

	u8 modrm_seg;

	u8 seg_override;

	u64 d;

	unsigned long _eip;

	struct operand memop;

arch/x86/kvm/emulate.c

+16 −25
Original line number Diff line number Diff line
@@ -514,12 +514,6 @@ static u32 desc_limit_scaled(struct desc_struct *desc) 
	return desc->g ? (limit << 12) | 0xfff : limit;

}



static void set_seg_override(struct x86_emulate_ctxt *ctxt, int seg)

{

	ctxt->has_seg_override = true;

	ctxt->seg_override = seg;

}



static unsigned long seg_base(struct x86_emulate_ctxt *ctxt, int seg)

{

	if (ctxt->mode == X86EMUL_MODE_PROT64 && seg < VCPU_SREG_FS)
@@ -528,14 +522,6 @@ static unsigned long seg_base(struct x86_emulate_ctxt *ctxt, int seg) 
	return ctxt->ops->get_cached_segment_base(ctxt, seg);

}



static unsigned seg_override(struct x86_emulate_ctxt *ctxt)

{

	if (!ctxt->has_seg_override)

		return 0;



	return ctxt->seg_override;

}



static int emulate_exception(struct x86_emulate_ctxt *ctxt, int vec,

			     u32 error, bool valid)

{
@@ -4169,7 +4155,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, 
		op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;

		op->addr.mem.ea =

			register_address(ctxt, reg_read(ctxt, VCPU_REGS_RSI));

		op->addr.mem.seg = seg_override(ctxt);

		op->addr.mem.seg = ctxt->seg_override;

		op->val = 0;

		op->count = 1;

		break;
@@ -4180,7 +4166,7 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op, 
			register_address(ctxt,

				reg_read(ctxt, VCPU_REGS_RBX) +

				(reg_read(ctxt, VCPU_REGS_RAX) & 0xff));

		op->addr.mem.seg = seg_override(ctxt);

		op->addr.mem.seg = ctxt->seg_override;

		op->val = 0;

		break;

	case OpImmFAddr:
@@ -4227,6 +4213,7 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) 
	int mode = ctxt->mode;

	int def_op_bytes, def_ad_bytes, goffset, simd_prefix;

	bool op_prefix = false;

	bool has_seg_override = false;

	struct opcode opcode;



	ctxt->memop.type = OP_NONE;
@@ -4280,11 +4267,13 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) 
		case 0x2e:	/* CS override */

		case 0x36:	/* SS override */

		case 0x3e:	/* DS override */

			set_seg_override(ctxt, (ctxt->b >> 3) & 3);

			has_seg_override = true;

			ctxt->seg_override = (ctxt->b >> 3) & 3;

			break;

		case 0x64:	/* FS override */

		case 0x65:	/* GS override */

			set_seg_override(ctxt, ctxt->b & 7);

			has_seg_override = true;

			ctxt->seg_override = ctxt->b & 7;

			break;

		case 0x40 ... 0x4f: /* REX */

			if (mode != X86EMUL_MODE_PROT64)
@@ -4422,17 +4411,19 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) 
	/* ModRM and SIB bytes. */

	if (ctxt->d & ModRM) {

		rc = decode_modrm(ctxt, &ctxt->memop);

		if (!ctxt->has_seg_override)

			set_seg_override(ctxt, ctxt->modrm_seg);

		if (!has_seg_override) {

			has_seg_override = true;

			ctxt->seg_override = ctxt->modrm_seg;

		}

	} else if (ctxt->d & MemAbs)

		rc = decode_abs(ctxt, &ctxt->memop);

	if (rc != X86EMUL_CONTINUE)

		goto done;



	if (!ctxt->has_seg_override)

		set_seg_override(ctxt, VCPU_SREG_DS);

	if (!has_seg_override)

		ctxt->seg_override = VCPU_SREG_DS;



	ctxt->memop.addr.mem.seg = seg_override(ctxt);

	ctxt->memop.addr.mem.seg = ctxt->seg_override;



	if (ctxt->memop.type == OP_MEM && ctxt->ad_bytes != 8)

		ctxt->memop.addr.mem.ea = (u32)ctxt->memop.addr.mem.ea;
@@ -4534,8 +4525,8 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *)) 


void init_decode_cache(struct x86_emulate_ctxt *ctxt)

{

	memset(&ctxt->has_seg_override, 0,

	       (void *)&ctxt->modrm - (void *)&ctxt->has_seg_override);

	memset(&ctxt->rip_relative, 0,

	       (void *)&ctxt->modrm - (void *)&ctxt->rip_relative);



	ctxt->io_read.pos = 0;

	ctxt->io_read.end = 0;