[PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to not depend on CR2

[PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to not depend on CR2

[Sheng Yang]

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From c7b60a362930679e24df27e6a412cdbdf1a55f69 Mon Sep 17 00:00:00 2001
From: Sheng Yang <sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Date: Thu, 15 Nov 2007 14:52:28 +0800
Subject: [PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to 
not depend on CR2

The current 'lods' and 'stos' is depending on incoming CR2 rather than decode
memory address from registers.

And 'cmpxchg8b' should be decode memory address too.

Signed-off-by: Sheng Yang <sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/kvm/x86_emulate.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index dfcbda5..c020010 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -214,7 +214,8 @@ static u16 twobyte_table[256] = {
 	0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov,
 	    DstReg | SrcMem16 | ModRM | Mov,
 	/* 0xC0 - 0xCF */
-	0, 0, 0, DstMem | SrcReg | ModRM | Mov, 0, 0, 0, ImplicitOps | ModRM,
+	0, 0, 0, DstMem | SrcReg | ModRM | Mov,
+	0, 0, 0, ImplicitOps | ModRM | MemAbs,
 	0, 0, 0, 0, 0, 0, 0, 0,
 	/* 0xD0 - 0xDF */
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -1533,7 +1534,9 @@ special_insn:
 	case 0xaa ... 0xab:	/* stos */
 		c->dst.type = OP_MEM;
 		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-		c->dst.ptr = (unsigned long *)cr2;
+		c->dst.ptr = (unsigned long *)register_address(
+						   ctxt->es_base,
+						   c->regs[VCPU_REGS_RDI]);
 		c->dst.val = c->regs[VCPU_REGS_RAX];
 		register_address_increment(c->regs[VCPU_REGS_RDI],
 				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
@@ -1543,9 +1546,13 @@ special_insn:
 		c->dst.type = OP_REG;
 		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
 		c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
-		if ((rc = ops->read_emulated(cr2, &c->dst.val,
-					     c->dst.bytes,
-					     ctxt->vcpu)) != 0)
+		if ((rc = ops->read_emulated(register_address(
+				c->override_base ? *c->override_base :
+						   ctxt->ds_base,
+						 c->regs[VCPU_REGS_RSI]),
+						 &c->dst.val,
+						 c->dst.bytes,
+						 ctxt->vcpu)) != 0)
 			goto done;
 
 		register_address_increment(c->regs[VCPU_REGS_RSI],
-- 
1.5.2


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From c7b60a362930679e24df27e6a412cdbdf1a55f69 Mon Sep 17 00:00:00 2001
From: Sheng Yang <sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Date: Thu, 15 Nov 2007 14:52:28 +0800
Subject: [PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to not depend on CR2

The current 'lods' and 'stos' is depending on incoming CR2 rather than decode
memory address from registers.

And 'cmpxchg8b' should be decode memory address too.

Signed-off-by: Sheng Yang <sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/kvm/x86_emulate.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index dfcbda5..c020010 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -214,7 +214,8 @@ static u16 twobyte_table[256] = {
 	0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov,
 	    DstReg | SrcMem16 | ModRM | Mov,
 	/* 0xC0 - 0xCF */
-	0, 0, 0, DstMem | SrcReg | ModRM | Mov, 0, 0, 0, ImplicitOps | ModRM,
+	0, 0, 0, DstMem | SrcReg | ModRM | Mov,
+	0, 0, 0, ImplicitOps | ModRM | MemAbs,
 	0, 0, 0, 0, 0, 0, 0, 0,
 	/* 0xD0 - 0xDF */
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -1533,7 +1534,9 @@ special_insn:
 	case 0xaa ... 0xab:	/* stos */
 		c->dst.type = OP_MEM;
 		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
-		c->dst.ptr = (unsigned long *)cr2;
+		c->dst.ptr = (unsigned long *)register_address(
+						   ctxt->es_base,
+						   c->regs[VCPU_REGS_RDI]);
 		c->dst.val = c->regs[VCPU_REGS_RAX];
 		register_address_increment(c->regs[VCPU_REGS_RDI],
 				       (ctxt->eflags & EFLG_DF) ? -c->dst.bytes
@@ -1543,9 +1546,13 @@ special_insn:
 		c->dst.type = OP_REG;
 		c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
 		c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
-		if ((rc = ops->read_emulated(cr2, &c->dst.val,
-					     c->dst.bytes,
-					     ctxt->vcpu)) != 0)
+		if ((rc = ops->read_emulated(register_address(
+				c->override_base ? *c->override_base :
+						   ctxt->ds_base,
+						 c->regs[VCPU_REGS_RSI]),
+						 &c->dst.val,
+						 c->dst.bytes,
+						 ctxt->vcpu)) != 0)
 			goto done;
 
 		register_address_increment(c->regs[VCPU_REGS_RSI],
-- 
1.5.2


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Re: [PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to not depend on CR2

[Avi Kivity]

Sheng Yang wrote:
> From c7b60a362930679e24df27e6a412cdbdf1a55f69 Mon Sep 17 00:00:00 2001
> From: Sheng Yang <sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Date: Thu, 15 Nov 2007 14:52:28 +0800
> Subject: [PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to 
> not depend on CR2
>
> The current 'lods' and 'stos' is depending on incoming CR2 rather than decode
> memory address from registers.
>   


Applied, thanks.

> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
> index dfcbda5..c020010 100644
> --- a/drivers/kvm/x86_emulate.c
> +++ b/drivers/kvm/x86_emulate.c
> @@ -214,7 +214,8 @@ static u16 twobyte_table[256] = {
>  	0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov,
>  	    DstReg | SrcMem16 | ModRM | Mov,
>  	/* 0xC0 - 0xCF */
> -	0, 0, 0, DstMem | SrcReg | ModRM | Mov, 0, 0, 0, ImplicitOps | ModRM,
> +	0, 0, 0, DstMem | SrcReg | ModRM | Mov,
> +	0, 0, 0, ImplicitOps | ModRM | MemAbs,
>  	0, 0, 0, 0, 0, 0, 0, 0,
>  	/* 0xD0 - 0xDF */
>  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>   

Dropped this part: ModRM and MemAbs are mutually exclusive. MemAbs is 
where you have an absolute address in the instruction that is not 
encoded with mod r/m.

Didn't see anything else about cmpchg{8,16}b.  Is something missing?


-- 
error compiling committee.c: too many arguments to function


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Re: [PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods', 'stos' to not depend on CR2

[Sheng Yang]

On Thursday 15 November 2007 18:05:30 Avi Kivity wrote:
> Sheng Yang wrote:
> > From c7b60a362930679e24df27e6a412cdbdf1a55f69 Mon Sep 17 00:00:00 2001
> > From: Sheng Yang <sheng.yang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> > Date: Thu, 15 Nov 2007 14:52:28 +0800
> > Subject: [PATCH 1/2] KVM: x86 emulator: modify 'cmpxchg8b', 'lods',
> > 'stos' to not depend on CR2
> >
> > The current 'lods' and 'stos' is depending on incoming CR2 rather than
> > decode memory address from registers.
>
> Applied, thanks.
>
> > diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
> > index dfcbda5..c020010 100644
> > --- a/drivers/kvm/x86_emulate.c
> > +++ b/drivers/kvm/x86_emulate.c
> > @@ -214,7 +214,8 @@ static u16 twobyte_table[256] = {
> >  	0, 0, ByteOp | DstReg | SrcMem | ModRM | Mov,
> >  	    DstReg | SrcMem16 | ModRM | Mov,
> >  	/* 0xC0 - 0xCF */
> > -	0, 0, 0, DstMem | SrcReg | ModRM | Mov, 0, 0, 0, ImplicitOps | ModRM,
> > +	0, 0, 0, DstMem | SrcReg | ModRM | Mov,
> > +	0, 0, 0, ImplicitOps | ModRM | MemAbs,
> >  	0, 0, 0, 0, 0, 0, 0, 0,
> >  	/* 0xD0 - 0xDF */
> >  	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
>
> Dropped this part: ModRM and MemAbs are mutually exclusive. MemAbs is
> where you have an absolute address in the instruction that is not
> encoded with mod r/m.
>
> Didn't see anything else about cmpchg{8,16}b.  Is something missing?

In fact, this was about cmpchg{8,16}b. And yes, you're right. I miss that. 
Only ModRM is needed.

-- 
Thanks
Yang, Sheng

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