linux-kernel - Re: [PATCH v3 08/11] x86/traps: Demand-populate PASID MSR via #GP

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Message-ID: <87iltub2t0.ffs@tglx>
Date:   Sat, 05 Feb 2022 01:00:11 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Tony Luck <tony.luck@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Ravi V Shankar <ravi.v.shankar@...el.com>
Cc:     iommu@...ts.linux-foundation.org, x86 <x86@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [PATCH v3 08/11] x86/traps: Demand-populate PASID MSR via #GP

On Fri, Jan 28 2022 at 12:29, Fenghua Yu wrote:

> All tasks start with PASID state disabled. This means that the first
> time they execute an ENQCMD instruction they will take a #GP fault.
>
> Modify the #GP fault handler to check if the "mm" for the task has
> already been allocated a PASID. If so, try to fix the #GP fault by
> loading the IA32_PASID MSR.
>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>