linux-kernel - RE: [PATCH 6/7] x86/traps: Fix up invalid PASID

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Message-ID: <877dy0pikd.fsf@nanos.tec.linutronix.de>
Date:   Tue, 28 Apr 2020 02:20:18 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Luck\, Tony" <tony.luck@...el.com>,
        "Raj\, Ashok" <ashok.raj@...el.com>
Cc:     "Yu\, Fenghua" <fenghua.yu@...el.com>,
        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>,
        "Hansen\, Dave" <dave.hansen@...el.com>,
        "Pan\, Jacob jun" <jacob.jun.pan@...el.com>,
        "Jiang\, Dave" <dave.jiang@...el.com>,
        "Mehta\, Sohil" <sohil.mehta@...el.com>,
        "Shankar\, Ravi V" <ravi.v.shankar@...el.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>,
        "iommu\@lists.linux-foundation.org" 
        <iommu@...ts.linux-foundation.org>
Subject: RE: [PATCH 6/7] x86/traps: Fix up invalid PASID

"Luck, Tony" <tony.luck@...el.com> writes:
>> Just for the record I also suggested to have a proper errorcode in the
>> #GP for ENQCMD and I surely did not suggest to avoid decoding the user
>> instructions.
>
> Is the heuristic to avoid decoding the user instructions OK (you are just pointing
> out that you should not be given credit for this part of the idea)?

I surely suggested the approach, but at the same time I asked for the
error code and did not say that instruction checking needs to be
avoided.

This comment was just to make it clear that there were other options
discussed. IOW, the changelog should have some explicit explanations
why:

 - the error code idea does not work (according to HW folks)

 - the instruction decoding has no real benefit because $REASONS

Thanks,

        tglx