[PATCH 0/3] KVM: emulate AAM, XLAT, SALC

[PATCH 0/3] KVM: emulate AAM, XLAT, SALC

[Paolo Bonzini]

These three instructions are not emulated, but can be found in
real mode code.

These are also good for stable, but they conflict before 3.9 and are
not really useful since emulate_invalid_guest_state defaulted to false.
So I'm not marking them for earlier releases.

Paolo Bonzini (3):
  KVM: emulator: emulate AAM
  KVM: emulator: emulate XLAT
  KVM: emulator: emulate SALC

 arch/x86/kvm/emulate.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

-- 
1.8.1.4

Re: [PATCH 3/3] KVM: emulator: emulate SALC

[Gleb Natapov]

On Thu, May 09, 2013 at 11:16:07AM +0200, Paolo Bonzini wrote:
> This is an almost-undocumented instruction available in 32-bit mode.
> I say "almost" undocumented because AMD documents it in their opcode
> maps just to say that it is unavailable in 64-bit mode (sections
> "A.2.1 One-Byte Opcodes" and "B.3 Invalid and Reassigned Instructions
> in 64-Bit Mode").
> 
> It is roughly equivalent to "sbb %al, %al" except it does not
> set the flags.  Use fastop to emulate it, but do not use the opcode
> directly because it would fail if the host is 64-bit!
> 
> Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
> Cc: stable@kernel.org # 3.9
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/emulate.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 210bb4e..f62d4c8 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -534,6 +534,9 @@ FOP_SETCC(setle)
>  FOP_SETCC(setnle)
>  FOP_END;
>  
> +FOP_START(salc) "pushf; sbb %al, %al; popf; ret \n\t"

FOP_RET

> +FOP_END;
> +
>  #define __emulate_1op_rax_rdx(ctxt, _op, _suffix, _ex)			\
>  	do {								\
>  		unsigned long _tmp;					\
> @@ -3951,7 +3954,8 @@ static const struct opcode opcode_table[256] = {
>  	G(Src2One | ByteOp, group2), G(Src2One, group2),
>  	G(Src2CL | ByteOp, group2), G(Src2CL, group2),
>  	I(DstAcc | SrcImmUByte | No64, em_aam),
> -	I(DstAcc | SrcImmUByte | No64, em_aad), N,
> +	I(DstAcc | SrcImmUByte | No64, em_aad),
> +	F(DstAcc | ByteOp | No64, em_salc),
>  	I(DstAcc | SrcXLat | ByteOp, em_mov),
>  	/* 0xD8 - 0xDF */
>  	N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,
> -- 
> 1.8.1.4

--
			Gleb.

Re: [PATCH 3/3] KVM: emulator: emulate SALC

[Paolo Bonzini]

Il 09/05/2013 11:25, Gleb Natapov ha scritto:
> On Thu, May 09, 2013 at 11:16:07AM +0200, Paolo Bonzini wrote:
>> This is an almost-undocumented instruction available in 32-bit mode.
>> I say "almost" undocumented because AMD documents it in their opcode
>> maps just to say that it is unavailable in 64-bit mode (sections
>> "A.2.1 One-Byte Opcodes" and "B.3 Invalid and Reassigned Instructions
>> in 64-Bit Mode").
>>
>> It is roughly equivalent to "sbb %al, %al" except it does not
>> set the flags.  Use fastop to emulate it, but do not use the opcode
>> directly because it would fail if the host is 64-bit!
>>
>> Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
>> Cc: stable@kernel.org # 3.9
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  arch/x86/kvm/emulate.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
>> index 210bb4e..f62d4c8 100644
>> --- a/arch/x86/kvm/emulate.c
>> +++ b/arch/x86/kvm/emulate.c
>> @@ -534,6 +534,9 @@ FOP_SETCC(setle)
>>  FOP_SETCC(setnle)
>>  FOP_END;
>>  
>> +FOP_START(salc) "pushf; sbb %al, %al; popf; ret \n\t"
> 
> FOP_RET

Ah, I missed that macro.  I was mimicking FOP_SETCC which doesn't use
it.  Will resend.

Paolo

>> +FOP_END;
>> +
>>  #define __emulate_1op_rax_rdx(ctxt, _op, _suffix, _ex)			\
>>  	do {								\
>>  		unsigned long _tmp;					\
>> @@ -3951,7 +3954,8 @@ static const struct opcode opcode_table[256] = {
>>  	G(Src2One | ByteOp, group2), G(Src2One, group2),
>>  	G(Src2CL | ByteOp, group2), G(Src2CL, group2),
>>  	I(DstAcc | SrcImmUByte | No64, em_aam),
>> -	I(DstAcc | SrcImmUByte | No64, em_aad), N,
>> +	I(DstAcc | SrcImmUByte | No64, em_aad),
>> +	F(DstAcc | ByteOp | No64, em_salc),
>>  	I(DstAcc | SrcXLat | ByteOp, em_mov),
>>  	/* 0xD8 - 0xDF */
>>  	N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,
>> -- 
>> 1.8.1.4
> 
> --
> 			Gleb.
> 

Re: [PATCH 3/3] KVM: emulator: emulate SALC

[Gleb Natapov]

On Thu, May 09, 2013 at 11:30:27AM +0200, Paolo Bonzini wrote:
> Il 09/05/2013 11:25, Gleb Natapov ha scritto:
> > On Thu, May 09, 2013 at 11:16:07AM +0200, Paolo Bonzini wrote:
> >> This is an almost-undocumented instruction available in 32-bit mode.
> >> I say "almost" undocumented because AMD documents it in their opcode
> >> maps just to say that it is unavailable in 64-bit mode (sections
> >> "A.2.1 One-Byte Opcodes" and "B.3 Invalid and Reassigned Instructions
> >> in 64-Bit Mode").
> >>
> >> It is roughly equivalent to "sbb %al, %al" except it does not
> >> set the flags.  Use fastop to emulate it, but do not use the opcode
> >> directly because it would fail if the host is 64-bit!
> >>
> >> Reported-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
> >> Cc: stable@kernel.org # 3.9
> >> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >> ---
> >>  arch/x86/kvm/emulate.c | 6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> >> index 210bb4e..f62d4c8 100644
> >> --- a/arch/x86/kvm/emulate.c
> >> +++ b/arch/x86/kvm/emulate.c
> >> @@ -534,6 +534,9 @@ FOP_SETCC(setle)
> >>  FOP_SETCC(setnle)
> >>  FOP_END;
> >>  
> >> +FOP_START(salc) "pushf; sbb %al, %al; popf; ret \n\t"
> > 
> > FOP_RET
> 
> Ah, I missed that macro.  I was mimicking FOP_SETCC which doesn't use
> it.  Will resend.
> 
I think it does not use it by mistake.

> Paolo
> 
> >> +FOP_END;
> >> +
> >>  #define __emulate_1op_rax_rdx(ctxt, _op, _suffix, _ex)			\
> >>  	do {								\
> >>  		unsigned long _tmp;					\
> >> @@ -3951,7 +3954,8 @@ static const struct opcode opcode_table[256] = {
> >>  	G(Src2One | ByteOp, group2), G(Src2One, group2),
> >>  	G(Src2CL | ByteOp, group2), G(Src2CL, group2),
> >>  	I(DstAcc | SrcImmUByte | No64, em_aam),
> >> -	I(DstAcc | SrcImmUByte | No64, em_aad), N,
> >> +	I(DstAcc | SrcImmUByte | No64, em_aad),
> >> +	F(DstAcc | ByteOp | No64, em_salc),
> >>  	I(DstAcc | SrcXLat | ByteOp, em_mov),
> >>  	/* 0xD8 - 0xDF */
> >>  	N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,
> >> -- 
> >> 1.8.1.4
> > 
> > --
> > 			Gleb.
> > 

--
			Gleb.