Commit 36089fed authored by Wei Yongjun's avatar Wei Yongjun Committed by Avi Kivity
Browse files

KVM: x86 emulator: disable writeback when decode dest operand 



This patch change to disable writeback when decode dest
operand if the dest type is ImplicitOps or not specified.

Signed-off-by: default avatarWei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 06cb7046

arch/x86/kvm/emulate.c

+6 −17
Original line number Diff line number Diff line
@@ -2627,9 +2627,6 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 


	/* Decode and fetch the destination operand: register or memory. */

	switch (c->d & DstMask) {

	case ImplicitOps:

		/* Special instructions do their own operand decoding. */

		return 0;

	case DstReg:

		decode_register_operand(&c->dst, c,

			 c->twobyte && (c->b == 0xb6 || c->b == 0xb7));
@@ -2664,6 +2661,11 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt) 
					 c->regs[VCPU_REGS_RDI]);

		c->dst.val = 0;

		break;

	case ImplicitOps:

		/* Special instructions do their own operand decoding. */

	default:

		c->dst.type = OP_NONE; /* Disable writeback. */

		return 0;

	}



done:
@@ -3115,7 +3117,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
	case 0xf5:	/* cmc */

		/* complement carry flag from eflags reg */

		ctxt->eflags ^= EFLG_CF;

		c->dst.type = OP_NONE;	/* Disable writeback. */

		break;

	case 0xf6 ... 0xf7:	/* Grp3 */

		if (!emulate_grp3(ctxt, ops))
@@ -3123,16 +3124,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
		break;

	case 0xf8: /* clc */

		ctxt->eflags &= ~EFLG_CF;

		c->dst.type = OP_NONE;	/* Disable writeback. */

		break;

	case 0xfa: /* cli */

		if (emulator_bad_iopl(ctxt, ops)) {

			emulate_gp(ctxt, 0);

			goto done;

		} else {

		} else

			ctxt->eflags &= ~X86_EFLAGS_IF;

			c->dst.type = OP_NONE;	/* Disable writeback. */

		}

		break;

	case 0xfb: /* sti */

		if (emulator_bad_iopl(ctxt, ops)) {
@@ -3141,16 +3139,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
		} else {

			ctxt->interruptibility = KVM_X86_SHADOW_INT_STI;

			ctxt->eflags |= X86_EFLAGS_IF;

			c->dst.type = OP_NONE;	/* Disable writeback. */

		}

		break;

	case 0xfc: /* cld */

		ctxt->eflags &= ~EFLG_DF;

		c->dst.type = OP_NONE;	/* Disable writeback. */

		break;

	case 0xfd: /* std */

		ctxt->eflags |= EFLG_DF;

		c->dst.type = OP_NONE;	/* Disable writeback. */

		break;

	case 0xfe: /* Grp4 */

	grp45:
@@ -3287,16 +3282,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
		break;

	case 0x06:

		emulate_clts(ctxt->vcpu);

		c->dst.type = OP_NONE;

		break;

	case 0x09:		/* wbinvd */

		kvm_emulate_wbinvd(ctxt->vcpu);

		c->dst.type = OP_NONE;

		break;

	case 0x08:		/* invd */

	case 0x0d:		/* GrpP (prefetch) */

	case 0x18:		/* Grp16 (prefetch/nop) */

		c->dst.type = OP_NONE;

		break;

	case 0x20: /* mov cr, reg */

		switch (c->modrm_reg) {
@@ -3349,7 +3341,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
			goto done;

		}

		rc = X86EMUL_CONTINUE;

		c->dst.type = OP_NONE;

		break;

	case 0x32:

		/* rdmsr */
@@ -3361,7 +3352,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
			c->regs[VCPU_REGS_RDX] = msr_data >> 32;

		}

		rc = X86EMUL_CONTINUE;

		c->dst.type = OP_NONE;

		break;

	case 0x34:		/* sysenter */

		rc = emulate_sysenter(ctxt, ops);
@@ -3385,7 +3375,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
	case 0x80 ... 0x8f: /* jnz rel, etc*/

		if (test_cc(c->b, ctxt->eflags))

			jmp_rel(c, c->src.val);

		c->dst.type = OP_NONE;

		break;

	case 0xa0:	  /* push fs */

		emulate_push_sreg(ctxt, ops, VCPU_SREG_FS);