From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Ashok Raj <ashok.raj@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
Ashok Raj <ashok_raj@linux.intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, Kostya Serebryany <kcc@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Alexander Potapenko <glider@google.com>,
Taras Madan <tarasmadan@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
"H . J . Lu" <hjl.tools@gmail.com>,
Andi Kleen <ak@linux.intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Jacon Jun Pan <jacob.jun.pan@intel.com>,
Jason Gunthorpe <jgg@nvidia.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCHv8 00/11] Linear Address Masking enabling
Date: Wed, 14 Sep 2022 18:45:32 +0300 [thread overview]
Message-ID: <20220914154532.mmxfsr7eadgnxt3s@box.shutemov.name> (raw)
In-Reply-To: <YyHz7H0uyqG58b3E@araj-MOBL2.amr.corp.intel.com>
On Wed, Sep 14, 2022 at 08:31:56AM -0700, Ashok Raj wrote:
> On Wed, Sep 14, 2022 at 06:18:18PM +0300, Kirill A. Shutemov wrote:
> > > > > >
> > > > > > The patch below implements something like this. It is PoC, build-tested only.
> > > > > >
> > > > > > To be honest, I hate it. It is clearly a layering violation. It feels
> > > > > > dirty. But I don't see any better way as we tie orthogonal features
> > > > > > together.
> > > > > >
> > > > > > Also I have no idea how to make forced PASID allocation if LAM enabled.
> > > > > > What the API has to look like?
> > > > >
> > > > > Jacob, Ashok, any comment on this part?
> > > > >
> > > > > I expect in many cases LAM will be enabled very early (like before malloc
> > > > > is functinal) in process start and it makes PASID allocation always fail.
> > > > >
> > > > > Any way out?
> > > >
> > > > We need closure on this to proceed. Any clue?
> > >
> > > Failing PASID allocation seems like the right thing to do here. If the
> > > application is explicitly allocating PASID's it can opt-out using the
> > > similar mechanism you have for LAM enabling. So user takes
> > > responsibility for sanitizing pointers.
> > >
> > > If some library is using an accelerator without application knowledge,
> > > that would use the failure as a mechanism to use an alternate path if
> > > one exists.
> > >
> > > I don't know if both LAM and SVM need a separate forced opt-in (or i
> > > don't have an opinion rather). Is this what you were asking?
> > >
> > > + Joerg, JasonG in case they have an opinion.
> >
> > My point is that the patch provides a way to override LAM vs. PASID mutual
> > exclusion, but only if PASID allocated first. If we enabled LAM before
> > PASID is allcoated there's no way to forcefully allocate PASID, bypassing
> > LAM check. I think there should be one, no?
>
> Yes, we should have one for force enabling SVM too if the application
> asks for forgiveness.
What is the right API here?
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2022-09-14 15:45 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 1:00 Kirill A. Shutemov
2022-08-30 1:00 ` [PATCHv8 01/11] x86/mm: Fix CR3_ADDR_MASK Kirill A. Shutemov
2022-08-30 1:00 ` [PATCHv8 02/11] x86: CPUID and CR3/CR4 flags for Linear Address Masking Kirill A. Shutemov
2022-08-30 1:00 ` [PATCHv8 03/11] mm: Pass down mm_struct to untagged_addr() Kirill A. Shutemov
2022-08-30 1:00 ` [PATCHv8 04/11] x86/mm: Handle LAM on context switch Kirill A. Shutemov
2022-08-30 1:00 ` [PATCHv8 05/11] x86/uaccess: Provide untagged_addr() and remove tags before address check Kirill A. Shutemov
2022-08-30 1:00 ` [PATCHv8 06/11] x86/mm: Provide arch_prctl() interface for LAM Kirill A. Shutemov
2022-08-30 1:01 ` [PATCHv8 07/11] x86: Expose untagging mask in /proc/$PID/arch_status Kirill A. Shutemov
2022-08-30 1:01 ` [PATCHv8 08/11] selftests/x86/lam: Add malloc and tag-bits test cases for linear-address masking Kirill A. Shutemov
2022-08-30 1:01 ` [PATCHv8 09/11] selftests/x86/lam: Add mmap and SYSCALL " Kirill A. Shutemov
2022-09-07 3:19 ` Robert Hoo
2022-09-09 11:24 ` Zhang, Weihong
2022-08-30 1:01 ` [PATCHv8 10/11] selftests/x86/lam: Add io_uring " Kirill A. Shutemov
2022-08-30 1:01 ` [PATCHv8 11/11] selftests/x86/lam: Add inherit " Kirill A. Shutemov
2022-09-01 17:45 ` [PATCHv8 00/11] Linear Address Masking enabling Ashok Raj
2022-09-04 0:39 ` Kirill A. Shutemov
2022-09-09 16:08 ` Ashok Raj
2022-09-12 20:39 ` Jacob Pan
2022-09-12 21:41 ` Dave Hansen
2022-09-12 22:55 ` Jacob Pan
2022-09-13 0:06 ` Kirill A. Shutemov
2022-09-13 0:23 ` Ashok Raj
2022-09-12 22:49 ` Kirill A. Shutemov
2022-09-13 0:08 ` Jacob Pan
2022-09-13 0:18 ` Kirill A. Shutemov
2022-09-14 14:45 ` Kirill A. Shutemov
2022-09-14 15:11 ` Ashok Raj
2022-09-14 15:18 ` Kirill A. Shutemov
2022-09-14 15:31 ` Ashok Raj
2022-09-14 15:45 ` Kirill A. Shutemov [this message]
2022-09-14 23:51 ` Jacob Pan
2022-09-15 9:01 ` Kirill A. Shutemov
2022-09-15 17:28 ` Kirill A. Shutemov
2022-09-20 13:14 ` Jason Gunthorpe
2022-09-20 14:57 ` Ashok Raj
2022-09-20 16:06 ` Dave Hansen
2022-09-20 16:27 ` Jason Gunthorpe
2022-09-20 18:41 ` Jacob Pan
2022-09-20 18:50 ` Jason Gunthorpe
2022-09-20 20:44 ` Jacob Pan
2022-09-21 0:01 ` Jason Gunthorpe
2022-09-21 9:36 ` Tian, Kevin
2022-09-21 16:57 ` Dave Hansen
2022-09-21 17:08 ` Ashok Raj
2022-09-21 17:11 ` Dave Hansen
2022-09-21 17:29 ` Ashok Raj
2022-09-21 18:11 ` Jason Gunthorpe
2022-09-23 0:42 ` Kirill A. Shutemov
2022-09-23 5:27 ` Ashok Raj
2022-09-23 9:38 ` Kirill A. Shutemov
2022-09-23 11:46 ` Jason Gunthorpe
2022-09-23 14:18 ` Dave Hansen
2022-09-23 14:42 ` Jason Gunthorpe
2022-09-23 14:59 ` Ashok Raj
2022-09-23 15:28 ` Ashok Raj
2022-09-23 15:31 ` Dave Hansen
2022-09-23 15:44 ` Ashok Raj
2022-09-23 16:23 ` Dave Hansen
2022-09-23 16:44 ` Jason Gunthorpe
2022-09-04 1:00 ` Kirill A. Shutemov
2022-09-05 5:05 ` Bharata B Rao
2022-09-05 13:44 ` Kirill A. Shutemov
2022-09-05 14:30 ` Peter Zijlstra
2022-09-05 15:35 ` Kirill A. Shutemov
2022-09-05 15:46 ` Peter Zijlstra
2022-09-05 16:47 ` Kirill A. Shutemov
2022-09-06 8:39 ` Peter Zijlstra
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