linux-kernel - Re: [PATCHv10 10/15] x86/mm, iommu/sva: Make LAM and SVM mutually exclusive

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Message-ID: <20221019001728.jvjtrkoe7aqmhfww@box.shutemov.name>
Date:   Wed, 19 Oct 2022 03:17:28 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
        Kostya Serebryany <kcc@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Taras Madan <tarasmadan@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        "H . J . Lu" <hjl.tools@...il.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Bharata B Rao <bharata@....com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv10 10/15] x86/mm, iommu/sva: Make LAM and SVM mutually
 exclusive

On Tue, Oct 18, 2022 at 03:43:24PM -0700, Dave Hansen wrote:
> On 10/18/22 15:33, Kirill A. Shutemov wrote:
> >> Is this #ifdef really necessary?  CONFIG_IOMMU_SVA selects IOASID,
> >> without which pasid_valid() is just stubbed out to 0.
> > mm->pasid is only defined for CONFIG_IOMMU_SVA=y.
> > 
> > Do you want me to add mm_has_valid_pasid()?
> 
> A quick grep makes it look like pasid_valid() could be *replaced* with
> mm_has_pasid_valid() since all the places doing pasid_valid() do it with
> mm->pasid.

Almost: the second pasid_valid() in iommu_sva_alloc_pasid() called for
just allocated pasid.

I guess we can just opencode this case.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov