linux-kernel - Re: [PATCH v5 3/7] x86/fpu/xstate: Differentiate default features for host and guest FPUs

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Message-ID: <6ca20733644279373227f1f9633527c4a96e30ef.camel@intel.com>
Date: Mon, 28 Apr 2025 15:42:21 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "seanjc@...gle.com" <seanjc@...gle.com>
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Subject: Re: [PATCH v5 3/7] x86/fpu/xstate: Differentiate default features for
 host and guest FPUs

On Fri, 2025-04-25 at 16:48 -0700, Sean Christopherson wrote:
> > (2) is an existing problem. But if we think KVM should have its own
> > feature set of bits for ABI purposes, it seems like maybe it should have
> > some
> > dedicated consideration. 
> 
> Nah, don't bother.  The kernel needs to solve the exact same problems for the
> signal ABI, I don't see any reason to generate more work.  From a validation
> coverage perspective, I see a lot of value in shared code.

Right, so there should be no need to keep a separate features and buffer size
for KVM's xsave UABI, as this patch does. Let's just leave it using the core
kernels UABI version.