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From: Dave Hansen <dave.hansen@intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Jacob Pan <jacob.jun.pan@intel.com>,
	Ashok Raj <ashok.raj@intel.com>,
	"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,
	Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCHv8 00/11] Linear Address Masking enabling
Date: Tue, 20 Sep 2022 09:06:32 -0700	[thread overview]
Message-ID: <15741fdf-68b6-bd32-b0c2-63fde3bb0db2@intel.com> (raw)
In-Reply-To: <Yym8zsuXbYaW3alU@nvidia.com>

On 9/20/22 06:14, Jason Gunthorpe wrote:
> For this I would rather have a function that queries the format of the
> page table under the mm_struct and we have enum values like
> INTEL_NORMAL and INTEL_LAM as possible values.
> 
> The iommu driver will block incompatible page table formats, and when
> it starts up it should assert something that blocks changing the
> format.

That doesn't sound too bad.  Except, please don't call it a "page table
format".  The format of the page tables does not change with LAM.  It's
entirely how the CPU interprets addresses that changes.

I guess someone could make an argument that, with LAM, there is a "hole"
that can't be filled in and _that_ constitutes a format change, but
that'd be a stretch.

The thing that matters when LAM is on is that some CPU might be stashing
addresses somewhere that only have meaning when you interpret them with
LAM rules.  That's really a property of the mm, not of the page tables.

Oh, and please don't call things "INTEL_WHATEVER".  It looks silly and
confuses the heck out of people when a second CPU vendor needs to use
the same code.


  parent reply	other threads:[~2022-09-20 16:06 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
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 [this message]
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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