linux-kernel - Re: [PATCH v8 1/1] selftests/x86/xstate: Add xstate test cases for XSAVE feature

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Date:   Thu, 24 Mar 2022 19:37:13 +0800
From:   Pengfei Xu <pengfei.xu@...el.com>
To:     "Chang S. Bae" <chang.seok.bae@...el.com>
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        linux-kselftest <linux-kselftest@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Heng Su <heng.su@...el.com>,
        Hansen Dave <dave.hansen@...el.com>,
        Luck Tony <tony.luck@...el.com>,
        Mehta Sohil <sohil.mehta@...el.com>,
        Chen Yu C <yu.c.chen@...el.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v8 1/1] selftests/x86/xstate: Add xstate test cases for
 XSAVE feature

On 2022-03-24 at 03:06:50 -0700, Chang S. Bae wrote:
> On 3/16/2022 5:40 AM, Pengfei Xu wrote:
> > 
> > +static inline void check_cpuid_xsave_availability(void)
> > +{
> > +	uint32_t eax, ebx, ecx, edx;
> > +
> > +	/*
> > +	 * CPUID.1:ECX.XSAVE[bit 26] enumerates general
> > +	 * support for the XSAVE feature set, including
> > +	 * XGETBV.
> > +	 */
> > +	__cpuid_count(1, 0, eax, ebx, ecx, edx);
> > +	if (!(ecx & CPUID_LEAF1_ECX_XSAVE_MASK))
> > +		fatal_error("cpuid: no CPU xsave support");
> > +	if (!(ecx & CPUID_LEAF1_ECX_OSXSAVE_MASK))
> > +		fatal_error("cpuid: no OS xsave support");
> 
> We need to skip the test when XSAVE is not available. See the point here:
> https://lore.kernel.org/lkml/8735j8aa9g.ffs@tglx/
> 
  Yes, it's better, will skip and exit if CPU doesn't support XSAVE or OS
  XSAVE.
  Thanks for suggestion!

  BR.
  -- Pengfei

> Thanks,
> Chang
> 
>