Commit 3d9b938e authored by Nelson Elhage's avatar Nelson Elhage Committed by Avi Kivity
Browse files

KVM: emulator: Use linearize() when fetching instructions 



Since segments need to be handled slightly differently when fetching
instructions, we add a __linearize helper that accepts a new 'fetch' boolean.

[avi: fix oops caused by wrong segmented_address initialization order]

Signed-off-by: default avatarNelson Elhage <nelhage@ksplice.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 7c4c0f4f

arch/x86/include/asm/kvm_emulate.h

+0 −1
Original line number Diff line number Diff line
@@ -265,7 +265,6 @@ struct x86_emulate_ctxt { 
	unsigned long eip; /* eip before instruction emulation */

	/* Emulated execution mode, represented by an X86EMUL_MODE value. */

	int mode;

	u32 cs_base;



	/* interruptibility state, as a result of execution of STI or MOV SS */

	int interruptibility;

arch/x86/kvm/emulate.c

+18 −8
Original line number Diff line number Diff line
@@ -540,9 +540,9 @@ static int emulate_nm(struct x86_emulate_ctxt *ctxt) 
	return emulate_exception(ctxt, NM_VECTOR, 0, false);

}



static int linearize(struct x86_emulate_ctxt *ctxt,

static int __linearize(struct x86_emulate_ctxt *ctxt,

		     struct segmented_address addr,

		     unsigned size, bool write,

		     unsigned size, bool write, bool fetch,

		     ulong *linear)

{

	struct decode_cache *c = &ctxt->decode;
@@ -569,7 +569,7 @@ static int linearize(struct x86_emulate_ctxt *ctxt, 
		if (((desc.type & 8) || !(desc.type & 2)) && write)

			goto bad;

		/* unreadable code segment */

		if ((desc.type & 8) && !(desc.type & 2))

		if (!fetch && (desc.type & 8) && !(desc.type & 2))

			goto bad;

		lim = desc_limit_scaled(&desc);

		if ((desc.type & 8) || !(desc.type & 4)) {
@@ -602,7 +602,7 @@ static int linearize(struct x86_emulate_ctxt *ctxt, 
		}

		break;

	}

	if (c->ad_bytes != 8)

	if (fetch ? ctxt->mode != X86EMUL_MODE_PROT64 : c->ad_bytes != 8)

		la &= (u32)-1;

	*linear = la;

	return X86EMUL_CONTINUE;
@@ -613,6 +613,15 @@ bad: 
		return emulate_gp(ctxt, addr.seg);

}



static int linearize(struct x86_emulate_ctxt *ctxt,

		     struct segmented_address addr,

		     unsigned size, bool write,

		     ulong *linear)

{

	return __linearize(ctxt, addr, size, write, false, linear);

}





static int segmented_read_std(struct x86_emulate_ctxt *ctxt,

			      struct segmented_address addr,

			      void *data,
@@ -637,11 +646,13 @@ static int do_fetch_insn_byte(struct x86_emulate_ctxt *ctxt, 
	int size, cur_size;



	if (eip == fc->end) {

		unsigned long linear = eip + ctxt->cs_base;

		if (ctxt->mode != X86EMUL_MODE_PROT64)

			linear &= (u32)-1;

		unsigned long linear;

		struct segmented_address addr = { .seg=VCPU_SREG_CS, .ea=eip};

		cur_size = fc->end - fc->start;

		size = min(15UL - cur_size, PAGE_SIZE - offset_in_page(eip));

		rc = __linearize(ctxt, addr, size, false, true, &linear);

		if (rc != X86EMUL_CONTINUE)

			return rc;

		rc = ops->fetch(linear, fc->data + cur_size,

				size, ctxt->vcpu, &ctxt->exception);

		if (rc != X86EMUL_CONTINUE)
@@ -3127,7 +3138,6 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) 
	c->fetch.end = c->fetch.start + insn_len;

	if (insn_len > 0)

		memcpy(c->fetch.data, insn, insn_len);

	ctxt->cs_base = seg_base(ctxt, ops, VCPU_SREG_CS);



	switch (mode) {

	case X86EMUL_MODE_REAL:

CRA Git | Maintained and supported by SUSTech CRA and CCSE