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[Qemu-devel] [PATCH] i386: correct cpu_x86_cpuid(0xd)

Sebastian Andrzej Siewior posted 1 patch 7 years, 1 month ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20180928104319.3296-1-bigeasy@linutronix.de
Test checkpatch passed
Test docker-clang@ubuntu failed
target/i386/cpu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
[Qemu-devel] [PATCH] i386: correct cpu_x86_cpuid(0xd)
Posted by Sebastian Andrzej Siewior 7 years, 1 month ago 
Intel SDM says for CPUID function 0DH, sub-function 0:

| • ECX enumerates the size (in bytes) required by the XSAVE instruction for an
|   XSAVE area containing all the user state components supported by this
|   processor.
| • EBX enumerates the size (in bytes) required by the XSAVE instruction for an
|   XSAVE area containing all the user state components corresponding to bits
|   currently set in XCR0.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 target/i386/cpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index f24295e6e4bb7..00c18444c0bac 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -4178,7 +4178,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             *ecx = xsave_area_size(x86_cpu_xsave_components(cpu));
             *eax = env->features[FEAT_XSAVE_COMP_LO];
             *edx = env->features[FEAT_XSAVE_COMP_HI];
-            *ebx = *ecx;
+            *ebx = xsave_area_size(env->xcr0);
         } else if (count == 1) {
             *eax = env->features[FEAT_XSAVE];
         } else if (count < ARRAY_SIZE(x86_ext_save_areas)) {
-- 
2.19.0
Re: [Qemu-devel] [PATCH] i386: correct cpu_x86_cpuid(0xd)
Posted by Eduardo Habkost 7 years, 1 month ago 
On Fri, Sep 28, 2018 at 12:43:19PM +0200, Sebastian Andrzej Siewior wrote:
> Intel SDM says for CPUID function 0DH, sub-function 0:
> 
> | • ECX enumerates the size (in bytes) required by the XSAVE instruction for an
> |   XSAVE area containing all the user state components supported by this
> |   processor.
> | • EBX enumerates the size (in bytes) required by the XSAVE instruction for an
> |   XSAVE area containing all the user state components corresponding to bits
> |   currently set in XCR0.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  target/i386/cpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index f24295e6e4bb7..00c18444c0bac 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -4178,7 +4178,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>              *ecx = xsave_area_size(x86_cpu_xsave_components(cpu));
>              *eax = env->features[FEAT_XSAVE_COMP_LO];
>              *edx = env->features[FEAT_XSAVE_COMP_HI];
> -            *ebx = *ecx;
> +            *ebx = xsave_area_size(env->xcr0);

Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>

For reference, KVM isn't affected by this bug because KVM kernel code updates
CPUID data at runtime, at:

int kvm_update_cpuid(struct kvm_vcpu *vcpu)
{
	[...]
	best = kvm_find_cpuid_entry(vcpu, 0xD, 0);
	if (!best) {
		[...]
	} else {
		[...]
		best->ebx = xstate_required_size(vcpu->arch.xcr0, false);
	}
	[...]
}


>          } else if (count == 1) {
>              *eax = env->features[FEAT_XSAVE];
>          } else if (count < ARRAY_SIZE(x86_ext_save_areas)) {
> -- 
> 2.19.0
> 

-- 
Eduardo
Re: [Qemu-devel] [PATCH] i386: correct cpu_x86_cpuid(0xd)
Posted by Sebastian Andrzej Siewior 7 years ago 
On 2018-09-28 11:54:11 [-0300], Eduardo Habkost wrote:
> On Fri, Sep 28, 2018 at 12:43:19PM +0200, Sebastian Andrzej Siewior wrote:
> > Intel SDM says for CPUID function 0DH, sub-function 0:
> > 
> > | • ECX enumerates the size (in bytes) required by the XSAVE instruction for an
> > |   XSAVE area containing all the user state components supported by this
> > |   processor.
> > | • EBX enumerates the size (in bytes) required by the XSAVE instruction for an
> > |   XSAVE area containing all the user state components corresponding to bits
> > |   currently set in XCR0.
> > 
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> > ---
> >  target/i386/cpu.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index f24295e6e4bb7..00c18444c0bac 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -4178,7 +4178,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
> >              *ecx = xsave_area_size(x86_cpu_xsave_components(cpu));
> >              *eax = env->features[FEAT_XSAVE_COMP_LO];
> >              *edx = env->features[FEAT_XSAVE_COMP_HI];
> > -            *ebx = *ecx;
> > +            *ebx = xsave_area_size(env->xcr0);
> 
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>

ping

Sebastian
Re: [Qemu-devel] [PATCH] i386: correct cpu_x86_cpuid(0xd)
Posted by Paolo Bonzini 7 years ago 
On 17/10/2018 20:12, Sebastian Andrzej Siewior wrote:
> On 2018-09-28 11:54:11 [-0300], Eduardo Habkost wrote:
>> On Fri, Sep 28, 2018 at 12:43:19PM +0200, Sebastian Andrzej Siewior wrote:
>>> Intel SDM says for CPUID function 0DH, sub-function 0:
>>>
>>> | • ECX enumerates the size (in bytes) required by the XSAVE instruction for an
>>> |   XSAVE area containing all the user state components supported by this
>>> |   processor.
>>> | • EBX enumerates the size (in bytes) required by the XSAVE instruction for an
>>> |   XSAVE area containing all the user state components corresponding to bits
>>> |   currently set in XCR0.
>>>
>>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>>> ---
>>>  target/i386/cpu.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>>> index f24295e6e4bb7..00c18444c0bac 100644
>>> --- a/target/i386/cpu.c
>>> +++ b/target/i386/cpu.c
>>> @@ -4178,7 +4178,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>>>              *ecx = xsave_area_size(x86_cpu_xsave_components(cpu));
>>>              *eax = env->features[FEAT_XSAVE_COMP_LO];
>>>              *edx = env->features[FEAT_XSAVE_COMP_HI];
>>> -            *ebx = *ecx;
>>> +            *ebx = xsave_area_size(env->xcr0);
>>
>> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> 
> ping

It's queued for my next pull request.

Paolo
Re: [Qemu-devel] [PATCH] i386: correct cpu_x86_cpuid(0xd)
Posted by Sebastian Andrzej Siewior 7 years ago 
On 2018-10-17 20:40:17 [+0200], Paolo Bonzini wrote:
> It's queued for my next pull request.

thanks.

> Paolo

Sebastian

Patchew 2.1-devel-b67e4c2

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