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Date:   Thu, 1 Dec 2022 06:04:45 -0800
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Subject: Re: [tip: x86/fpu] x86/fpu/xstate: Define new functions for clearing
 fpregs and xstates
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To:     Ivan Zahariev <famzah@icdsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "Yu, Yu-cheng" <yu-cheng.yu@intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     linux-tip-commits@vger.kernel.org,
        Fenghua Yu <fenghua.yu@intel.com>,
        Borislav Petkov <bp@suse.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Tony Luck <tony.luck@intel.com>, x86 <x86@kernel.org>,
        "Shankar, Ravi V" <ravi.v.shankar@intel.com>
References: <20200512145444.15483-6-yu-cheng.yu@intel.com>
 <158964181793.17951.15480349640697746223.tip-bot2@tip-bot2>
 <CALCETrXfLbsrBX42Y094YLWTG=pqkrf+aSCLruCGzqnZ0Y=P-Q@mail.gmail.com>
 <10a553a5-699f-6921-705e-9afa1a8e42de@intel.com>
 <87y2c28zir.ffs@nanos.tec.linutronix.de>
 <ff5ad474-6d32-8bf8-e297-ed71a967d27c@icdsoft.com>
 <31b30c00-9de9-2881-53c3-b08804571d6c@intel.com>
 <212daa8e-8f48-30d9-cfc8-ee5c2025f02c@icdsoft.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <212daa8e-8f48-30d9-cfc8-ee5c2025f02c@icdsoft.com>
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On 12/1/22 04:58, Ivan Zahariev wrote:
> We are running 5.15.75 (LTS) but the problem started when we upgraded
> from 5.15.31 to 5.15.59 and is present ever since. I erroneously said
> that it's present into every 5.15.
> I didn't do my homework well and blamed the commit by Yu-cheng Yu. 
> But this commit never landed into 5.15, nor the fix commit that you>
> referred. There are no functions fpu__clear_all(), 
> copy_init_fpstate_to_fpregs(), copy_user_to_xstate() anywhere in the>
> sources of 5.15.75 or 5.15.31, so the 5.15 kernel is running with a 
> different FPU implementation.
It's also possible that the Ubuntu kernel folks pulled some FPU patches
into their 5.15 kernel from later upstream kernels, which is adding to
the confusion.  I think there may have been some effort to backport the
AMX work.

You might want to file a bug report with the Ubuntu folks.