linux-kernel - Re: [PATCH v3 09/10] x86/fpu/xstate: Introduce XFEATURE_MASK_KERNEL

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Message-ID: <Z9AsGFF2Rs0lCC9/@intel.com>
Date: Tue, 11 Mar 2025 20:27:04 +0800
From: Chao Gao <chao.gao@...el.com>
To: "Chang S. Bae" <chang.seok.bae@...el.com>
CC: <tglx@...utronix.de>, <dave.hansen@...el.com>, <x86@...nel.org>,
	<seanjc@...gle.com>, <pbonzini@...hat.com>, <linux-kernel@...r.kernel.org>,
	<kvm@...r.kernel.org>, <peterz@...radead.org>, <rick.p.edgecombe@...el.com>,
	<weijiang.yang@...el.com>, <john.allen@....com>, <bp@...en8.de>
Subject: Re: [PATCH v3 09/10] x86/fpu/xstate: Introduce
 XFEATURE_MASK_KERNEL_DYNAMIC xfeature set

On Mon, Mar 10, 2025 at 01:53:09PM +0800, Chao Gao wrote:
>On Sun, Mar 09, 2025 at 10:20:47PM -0700, Chang S. Bae wrote:
>>On 3/9/2025 8:49 PM, Chao Gao wrote:
>>> 
>>> It was suggested by Sean [1].
>>...
>>> [1]: https://lore.kernel.org/kvm/ZTf5wPKXuHBQk0AN@google.com/
>>
>>But, you're defining a kernel "dynamic" feature while introducing a
>>"guest-only" xfeature concept. Both seem to be mixed together with this
>>patch. Why not call it as a guest-only feature? That's what Sean was
>>suggesting, no?
>
>Yes. I agree that we should call it as a guest-only feature. That's also why I
>included a note in this patch below the "---" to seek feedback on the naming:
>
>	I am tempted to rename XFEATURE_MASK_KERNEL_DYNAMIC to
>	XFEATURE_MASK_GUEST_ONLY. But I am not sure if this was discussed
>	and rejected.
>
>Thanks for confirming that the renaming is necessary.

Hi Chang,

I dug through the history and found a discussion about the naming at:

https://lore.kernel.org/all/893ac578-baaf-4f4f-96ee-e012dfc073a8@intel.com/#t

I think I should revise the changelog to call out why 'DYNAMIC' is preferred
over 'GUEST' and reference that discussion.