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[1/4] KVM: selftests: x86: Fix an error in comment of amx_test

Message ID 20230110185823.1856951-2-mizhang@google.com
State New
Headers show
Series [1/4] KVM: selftests: x86: Fix an error in comment of amx_test | expand

Commit Message

Mingwei Zhang Jan. 10, 2023, 6:58 p.m. UTC
After the execution of __tilerelease(), AMX component will be in INIT
state. Therefore, execution of xsavec saving the AMX state into memory will
cause the XSTATE_BV[18] cleared in xheader. However, the XCOMP_BV[18] will
remain set. Fix the error in comment.

Cc: Jim Mattson <jmattson@google.com>
Cc: Venkatesh Srinivas <venkateshs@google.com>
Cc: Aaron Lewis <aaronlewis@google.com>

Signed-off-by: Mingwei Zhang <mizhang@google.com>
---
 tools/testing/selftests/kvm/x86_64/amx_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Sean Christopherson Feb. 8, 2023, 1:13 a.m. UTC | #1
On Tue, Jan 10, 2023, Mingwei Zhang wrote:
> After the execution of __tilerelease(), AMX component will be in INIT
> state. Therefore, execution of xsavec saving the AMX state into memory will

s/xsavec/XSAVEC

> cause the XSTATE_BV[18] cleared in xheader. However, the XCOMP_BV[18] will
> remain set. Fix the error in comment.
> 
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Venkatesh Srinivas <venkateshs@google.com>
> Cc: Aaron Lewis <aaronlewis@google.com>
> 

No need for a blank line.

> Signed-off-by: Mingwei Zhang <mizhang@google.com>
> ---
>  tools/testing/selftests/kvm/x86_64/amx_test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
> index bd72c6eb3b67..16533949a189 100644
> --- a/tools/testing/selftests/kvm/x86_64/amx_test.c
> +++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
> @@ -204,7 +204,7 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
>  	GUEST_SYNC(4);
>  	__tilerelease();
>  	GUEST_SYNC(5);
> -	/* bit 18 not in the XCOMP_BV after xsavec() */
> +	/* bit 18 not in the XSTATE_BV after xsavec() */

I would rather overhaul the entire comment, e.g.

	/* Verify XTILEDATA is not set in XSTATE_BV after XSAVEC */

I had to look at the definition of XFEATURE_XTILEDATA to verify that yes, indeed,
bit 18 is XTILEDATA.

As for xsavec() vs. XSAVE, IIUC the clearing of XCOMP_BV[18] is a side effect of
XSAVEC the instruction, not something extra done by xsavec() the function.

>  	set_xstatebv(xsave_data, XFEATURE_MASK_XTILEDATA);
>  	__xsavec(xsave_data, XFEATURE_MASK_XTILEDATA);
>  	GUEST_ASSERT((get_xstatebv(xsave_data) & XFEATURE_MASK_XTILEDATA) == 0);
> -- 
> 2.39.0.314.g84b9a713c41-goog
>
Mingwei Zhang Feb. 13, 2023, 6:57 p.m. UTC | #2
On Tue, Feb 7, 2023 at 5:13 PM Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, Jan 10, 2023, Mingwei Zhang wrote:
> > After the execution of __tilerelease(), AMX component will be in INIT
> > state. Therefore, execution of xsavec saving the AMX state into memory will
>
> s/xsavec/XSAVEC
>
> > cause the XSTATE_BV[18] cleared in xheader. However, the XCOMP_BV[18] will
> > remain set. Fix the error in comment.
> >
> > Cc: Jim Mattson <jmattson@google.com>
> > Cc: Venkatesh Srinivas <venkateshs@google.com>
> > Cc: Aaron Lewis <aaronlewis@google.com>
> >
>
> No need for a blank line.

ack.
>
> > Signed-off-by: Mingwei Zhang <mizhang@google.com>
> > ---
> >  tools/testing/selftests/kvm/x86_64/amx_test.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
> > index bd72c6eb3b67..16533949a189 100644
> > --- a/tools/testing/selftests/kvm/x86_64/amx_test.c
> > +++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
> > @@ -204,7 +204,7 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
> >       GUEST_SYNC(4);
> >       __tilerelease();
> >       GUEST_SYNC(5);
> > -     /* bit 18 not in the XCOMP_BV after xsavec() */
> > +     /* bit 18 not in the XSTATE_BV after xsavec() */
>
> I would rather overhaul the entire comment, e.g.
>
>         /* Verify XTILEDATA is not set in XSTATE_BV after XSAVEC */
>
> I had to look at the definition of XFEATURE_XTILEDATA to verify that yes, indeed,
> bit 18 is XTILEDATA.
>
> As for xsavec() vs. XSAVE, IIUC the clearing of XCOMP_BV[18] is a side effect of
> XSAVEC the instruction, not something extra done by xsavec() the function.

I see, that's why you asked me to use capital words.
>
> >       set_xstatebv(xsave_data, XFEATURE_MASK_XTILEDATA);
> >       __xsavec(xsave_data, XFEATURE_MASK_XTILEDATA);
> >       GUEST_ASSERT((get_xstatebv(xsave_data) & XFEATURE_MASK_XTILEDATA) == 0);
> > --
> > 2.39.0.314.g84b9a713c41-goog
> >
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index bd72c6eb3b67..16533949a189 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -204,7 +204,7 @@  static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
 	GUEST_SYNC(4);
 	__tilerelease();
 	GUEST_SYNC(5);
-	/* bit 18 not in the XCOMP_BV after xsavec() */
+	/* bit 18 not in the XSTATE_BV after xsavec() */
 	set_xstatebv(xsave_data, XFEATURE_MASK_XTILEDATA);
 	__xsavec(xsave_data, XFEATURE_MASK_XTILEDATA);
 	GUEST_ASSERT((get_xstatebv(xsave_data) & XFEATURE_MASK_XTILEDATA) == 0);