linux-kernel - Re: [PATCH 3/7] x86/fpu/xstate: Add supervisor PASID state for ENQCMD feature

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Date:   Mon, 27 Apr 2020 13:33:41 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Jacob Jun Pan <jacob.jun.pan@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Sohil Mehta <sohil.mehta@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>, iommu@...ts.linux-foundation.org,
        Yu-cheng Yu <yu-cheng.yu@...el.com>
Subject: Re: [PATCH 3/7] x86/fpu/xstate: Add supervisor PASID state for
 ENQCMD feature

On Sun, Apr 26, 2020 at 01:17:11PM +0200, Thomas Gleixner wrote:
> Fenghua Yu <fenghua.yu@...el.com> writes:
> > From: Yu-cheng Yu <yu-cheng.yu@...el.com>
> >
> > The IA32_PASID MSR is used when a task submits work via the ENQCMD
> > instruction.
> 
> Is used?
> 
> > The per task MSR is stored in the task's supervisor FPU
> 
> per task MSR? Lot's of MSRs ....
> 
> > PASID state and is context switched by XSAVES/XRSTORS.
> >

Maybe change the commit messge to the following?

ENQCMD instruction reads PASID from IA32_PASID MSR. The MSR is stored
in the task's supervisor FPU PASID state and is context switched by
XSAVES/XRSTORS.

Thanks.

-Fenghua