From: Jason Gunthorpe <jgg@nvidia.com>
To: Alistair Popple <apopple@nvidia.com>
Cc: <linux-mm@kvack.org>, <nouveau@lists.freedesktop.org>,
<bskeggs@redhat.com>, <akpm@linux-foundation.org>,
<linux-doc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<dri-devel@lists.freedesktop.org>, <jhubbard@nvidia.com>,
<rcampbell@nvidia.com>, <jglisse@redhat.com>, <hch@infradead.org>,
<daniel@ffwll.ch>
Subject: Re: [PATCH v3 5/8] mm: Device exclusive memory access
Date: Mon, 1 Mar 2021 13:54:52 -0400 [thread overview]
Message-ID: <20210301175452.GR4247@nvidia.com> (raw)
In-Reply-To: <20210226071832.31547-6-apopple@nvidia.com>
On Fri, Feb 26, 2021 at 06:18:29PM +1100, Alistair Popple wrote:
> Some devices require exclusive write access to shared virtual
> memory (SVM) ranges to perform atomic operations on that memory. This
> requires CPU page tables to be updated to deny access whilst atomic
> operations are occurring.
>
> In order to do this introduce a new swap entry
> type (SWP_DEVICE_EXCLUSIVE). When a SVM range needs to be marked for
> exclusive access by a device all page table mappings for the particular
> range are replaced with device exclusive swap entries. This causes any
> CPU access to the page to result in a fault.
>
> Faults are resovled by replacing the faulting entry with the original
> mapping. This results in MMU notifiers being called which a driver uses
> to update access permissions such as revoking atomic access. After
> notifiers have been called the device will no longer have exclusive
> access to the region.
This makes alot more sense than the prior versions!
I don't know the migration area especially well, but nothing caught my
eye in here
Jason
next prev parent reply other threads:[~2021-03-01 17:55 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 7:18 [PATCH v3 0/8] Add support for SVM atomics in Nouveau Alistair Popple
2021-02-26 7:18 ` [PATCH v3 1/8] mm: Remove special swap entry functions Alistair Popple
2021-02-26 15:59 ` Christoph Hellwig
2021-03-02 8:52 ` Alistair Popple
2021-03-01 17:46 ` Jason Gunthorpe
2021-03-02 0:21 ` Alistair Popple
2021-02-26 7:18 ` [PATCH v3 2/8] mm/swapops: Rework swap entry manipulation code Alistair Popple
2021-02-26 16:00 ` Christoph Hellwig
2021-03-01 17:47 ` Jason Gunthorpe
2021-02-26 7:18 ` [PATCH v3 3/8] mm/rmap: Split try_to_munlock from try_to_unmap Alistair Popple
2021-02-26 16:01 ` Christoph Hellwig
2021-03-01 16:10 ` Jason Gunthorpe
2021-03-04 4:27 ` Alistair Popple
2021-02-26 7:18 ` [PATCH v3 4/8] mm/rmap: Split migration into its own function Alistair Popple
2021-02-26 16:03 ` Christoph Hellwig
[not found] ` <E93F89E1-3CE2-4CA3-97D9-6BCED78E1001@nvidia.com>
2021-03-04 23:54 ` Alistair Popple
2021-02-26 7:18 ` [PATCH v3 5/8] mm: Device exclusive memory access Alistair Popple
2021-03-01 17:54 ` Jason Gunthorpe [this message]
2021-03-01 22:55 ` Ralph Campbell
2021-03-02 0:05 ` Jason Gunthorpe
2021-03-02 8:57 ` Alistair Popple
[not found] ` <20210302124152.GF4247@nvidia.com>
2021-03-04 5:20 ` Alistair Popple
2021-02-26 7:18 ` [PATCH v3 6/8] mm: Selftests for exclusive device memory Alistair Popple
2021-03-01 17:55 ` Jason Gunthorpe
2021-03-01 18:07 ` Ralph Campbell
2021-03-01 23:14 ` Ralph Campbell
2021-03-02 9:12 ` Alistair Popple
2021-02-26 7:18 ` [PATCH v3 7/8] nouveau/svm: Refactor nouveau_range_fault Alistair Popple
2021-02-26 7:18 ` [PATCH v3 8/8] nouveau/svm: Implement atomic SVM access Alistair Popple
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