linux-kernel - Re: [patch 0/7] x86/fpu: Cure supervisor mode (ENQCMD) fallout

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Message-ID: <d723e20a-b461-f63e-2fd1-eea91b0dddf1@intel.com>
Date:   Mon, 28 Mar 2022 05:39:02 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
CC:     <x86@...nel.org>, Paolo Bonzini <bonzini@....org>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>
Subject: Re: [patch 0/7] x86/fpu: Cure supervisor mode (ENQCMD) fallout

On 3/24/2022 6:47 AM, Thomas Gleixner wrote:
> 
> It builds, boots on host and guest, but is not yet extensively tested.
> Testing with a AMX + PASID enabled machine has not been done at all as I
> don't have easy access to such a beast.

The AMX tests [1][2] went well on both host and guest. Also dmesg logs 
look to be okay:

On host,

$ sudo dmesg | grep fpu
[    0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating 
point registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x020: 'AVX-512 opmask'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x040: 'AVX-512 Hi256'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x080: 'AVX-512 ZMM_Hi256'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x200: 'Protection Keys 
User registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x400: 'PASID state'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x20000: 'AMX Tile config'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x40000: 'AMX Tile data'
[    0.000000] x86/fpu: xstate_offset[2]:  576, xstate_sizes[2]:  256
[    0.000000] x86/fpu: xstate_offset[5]:  832, xstate_sizes[5]:   64
[    0.000000] x86/fpu: xstate_offset[6]:  896, xstate_sizes[6]:  512
[    0.000000] x86/fpu: xstate_offset[7]: 1408, xstate_sizes[7]: 1024
[    0.000000] x86/fpu: xstate_offset[9]: 2432, xstate_sizes[9]:    8
[    0.000000] x86/fpu: xstate_offset[10]: 2440, xstate_sizes[10]:    8
[    0.000000] x86/fpu: xstate_offset[17]: 2496, xstate_sizes[17]:   64
[    0.000000] x86/fpu: xstate_offset[18]: 2560, xstate_sizes[18]: 8192
[    0.000000] x86/fpu: Enabled xstate features 0x606e7, context size is 
10752 bytes, using 'compacted' format.

On guest,
(AMX is available with the upstream Qemu [3].)

$ sudo dmesg | grep fpu
...
[    0.000000] x86/fpu: Supporting XSAVE feature 0x200: 'Protection Keys 
User registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x20000: 'AMX Tile config'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x40000: 'AMX Tile data'
...
[    0.000000] x86/fpu: xstate_offset[9]: 2432, xstate_sizes[9]:    8
[    0.000000] x86/fpu: xstate_offset[17]: 2496, xstate_sizes[17]:   64
[    0.000000] x86/fpu: xstate_offset[18]: 2560, xstate_sizes[18]: 8192
[    0.000000] x86/fpu: Enabled xstate features 0x602e7, context size is 
10752 bytes, using 'compacted' format.

Thanks,
Chang

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/tree/tools/testing/selftests/x86/amx.c?h=x86/fpu
[2] 
https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/tree/tools/testing/selftests/kvm/x86_64/amx_test.c?h=x86/fpu
[3] 
https://git.qemu.org/?p=qemu.git;a=commit;h=3d31fe4d662f13c70eb7e87f29513623ccd76322