From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"Luck, Tony" <tony.luck@intel.com>,
Andy Lutomirski <luto@kernel.org>,
Rik van Riel <riel@surriel.com>,
"Shankar, Ravi V" <ravi.v.shankar@intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
"Yu, Fenghua" <fenghua.yu@intel.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 1/6] x86/fpu/xstate: Fix small issues before adding supervisor xstates
Date: Fri, 22 Nov 2019 13:22:37 -0800 [thread overview]
Message-ID: <b33151bdfb5611de7db8493cb8fcca4b8f372267.camel@intel.com> (raw)
In-Reply-To: <20191009155847.GE10395@zn.tnic>
On Wed, 2019-10-09 at 08:58 -0700, Borislav Petkov wrote:
> On Wed, Sep 25, 2019 at 08:10:17AM -0700, Yu-cheng Yu wrote:
> > In response to earlier comments, fix small issues before introducing XSAVES
> > supervisor states:
> > - Add spaces around '*'.
> > - Fix comments of xfeature_is_supervisor().
> > - Replace ((u64)1 << 63) with XCOMP_BV_COMPACTED_FORMAT.
> >
> > No functional changes from this patch.
> >
> > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> > Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
> > Reviewed-by: Tony Luck <tony.luck@intel.com>
> > ---
> > arch/x86/kernel/fpu/xstate.c | 15 ++++++---------
> > 1 file changed, 6 insertions(+), 9 deletions(-)
> >
> > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
> > index e5cb67d67c03..b793fc2156b9 100644
> > --- a/arch/x86/kernel/fpu/xstate.c
> > +++ b/arch/x86/kernel/fpu/xstate.c
> > @@ -60,7 +60,7 @@ u64 xfeatures_mask __read_mostly;
> >
> > static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
> > static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
> > -static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8];
> > +static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask) * 8];
> >
> > /*
> > * The XSAVE area of kernel can be in standard or compacted format;
> > @@ -110,12 +110,8 @@ EXPORT_SYMBOL_GPL(cpu_has_xfeatures);
> > static int xfeature_is_supervisor(int xfeature_nr)
> > {
> > /*
> > - * We currently do not support supervisor states, but if
> > - * we did, we could find out like this.
> > - *
> > - * SDM says: If state component 'i' is a user state component,
> > - * ECX[0] return 0; if state component i is a supervisor
> > - * state component, ECX[0] returns 1.
> > + * Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1)
> > + * returns ECX[0] set to (1) for a supervisor state.
>
> "... and cleared (0) for a user state."
>
> I believe it is is clearer this way.
>
> > */
> > u32 eax, ebx, ecx, edx;
> >
>
> Since you're touching this function: make it return bool as it is used
> in boolean context only and have it return simply:
>
> return ecx & 1;
This implicitly converts a u32 to a bool. By looking at it, I think it should
be OK, but wonder if anything overlooked? I would be happy to make this a
separate patch.
Yu-cheng
next prev parent reply other threads:[~2019-11-22 21:33 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-25 15:10 [PATCH 0/6] Support XSAVES supervisor states Yu-cheng Yu
2019-09-25 15:10 ` [PATCH 1/6] x86/fpu/xstate: Fix small issues before adding supervisor xstates Yu-cheng Yu
2019-10-09 15:58 ` Borislav Petkov
2019-11-22 21:22 ` Yu-cheng Yu [this message]
2019-11-22 21:54 ` Borislav Petkov
2019-09-25 15:10 ` [PATCH 2/6] x86/fpu/xstate: Define new macros for supervisor and user xstates Yu-cheng Yu
2019-10-09 16:17 ` Borislav Petkov
2019-09-25 15:10 ` [PATCH 3/6] x86/fpu/xstate: Separate user and supervisor xfeatures mask Yu-cheng Yu
2019-10-09 16:59 ` Borislav Petkov
2019-09-25 15:10 ` [PATCH 4/6] x86/fpu/xstate: Introduce XSAVES supervisor states Yu-cheng Yu
2019-10-09 17:10 ` Borislav Petkov
2019-09-25 15:10 ` [PATCH 5/6] x86/fpu/xstate: Define new functions for clearing fpregs and xstates Yu-cheng Yu
2019-10-09 17:28 ` Borislav Petkov
2019-09-25 15:10 ` [PATCH 6/6] x86/fpu/xstate: Rename validate_xstate_header() to validate_xstate_header_from_user() Yu-cheng Yu
2019-10-09 17:31 ` Borislav Petkov
2019-10-09 22:10 ` Yu-cheng Yu
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