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

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Message-ID: <eb0c4940-569b-656f-424c-4248929cc74c@intel.com>
Date:   Thu, 24 Mar 2022 03:06:50 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     Pengfei Xu <pengfei.xu@...el.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-kselftest <linux-kselftest@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
CC:     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 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/

Thanks,
Chang