From: "Thomas Hellström (Intel)" <thomas_os@shipmail.org>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: "Alex Sierra" <alex.sierra@amd.com>,
"Philip Yang" <Philip.Yang@amd.com>,
"Felix Kuehling" <Felix.Kuehling@amd.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH 17/35] drm/amdkfd: register HMM device private zone
Date: Mon, 1 Mar 2021 10:30:12 +0100 [thread overview]
Message-ID: <4439d7b1-3ee3-b697-6edc-48b69f4638b9@shipmail.org> (raw)
In-Reply-To: <YDyswwICD3KmsBrf@phenom.ffwll.local>
On 3/1/21 9:58 AM, Daniel Vetter wrote:
> On Mon, Mar 01, 2021 at 09:46:44AM +0100, Thomas Hellström (Intel) wrote:
>> On 3/1/21 9:32 AM, Daniel Vetter wrote:
>>> On Wed, Jan 06, 2021 at 10:01:09PM -0500, Felix Kuehling wrote:
>>>> From: Philip Yang <Philip.Yang@amd.com>
>>>>
>>>> Register vram memory as MEMORY_DEVICE_PRIVATE type resource, to
>>>> allocate vram backing pages for page migration.
>>>>
>>>> Signed-off-by: Philip Yang <Philip.Yang@amd.com>
>>>> Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
>>> So maybe I'm getting this all wrong, but I think that the current ttm
>>> fault code relies on devmap pte entries (especially for hugepte entries)
>>> to stop get_user_pages. But this only works if the pte happens to not
>>> point at a range with devmap pages.
>> I don't think that's in TTM yet, but the proposed fix, yes (see email I just
>> sent in another thread),
>> but only for huge ptes.
>>
>>> This patch here changes that, and so probably breaks this devmap pte hack
>>> ttm is using?
>>>
>>> If I'm not wrong here then I think we need to first fix up the ttm code to
>>> not use the devmap hack anymore, before a ttm based driver can register a
>>> dev_pagemap. Also adding Thomas since that just came up in another
>>> discussion.
>> It doesn't break the ttm devmap hack per se, but it indeed allows gup to the
>> range registered, but here's where my lack of understanding why we can't
>> allow gup-ing TTM ptes if there indeed is a backing struct-page? Because
>> registering MEMORY_DEVICE_PRIVATE implies that, right?
> We need to keep supporting buffer based memory management for all the
> non-compute users. Because those require end-of-batch dma_fence semantics,
> which prevents us from using gpu page faults, which makes hmm not really
> work.
>
> And for buffer based memory manager we can't have gup pin random pages in
> there, that's not really how it works. Worst case ttm just assumes it can
> actually move buffers and reallocate them as it sees fit, and your gup
> mapping (for direct i/o or whatever) now points at a page of a buffer that
> you don't even own anymore. That's not good. Hence also all the
> discussions about preventing gup for bo mappings in general.
>
> Once we throw hmm into the mix we need to be really careful that the two
> worlds don't collide. Pure hmm is fine, pure bo managed memory is fine,
> mixing them is tricky.
> -Daniel
Hmm, OK so then registering MEMORY_DEVICE_PRIVATE means we can't set
pxx_devmap because that would allow gup, which, in turn, means no huge
TTM ptes.
/Thomas
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next prev parent reply other threads:[~2021-03-01 9:30 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 3:00 [PATCH 00/35] Add HMM-based SVM memory manager to KFD Felix Kuehling
2021-01-07 3:00 ` [PATCH 01/35] drm/amdkfd: select kernel DEVICE_PRIVATE option Felix Kuehling
2021-01-07 3:00 ` [PATCH 02/35] drm/amdgpu: replace per_device_list by array Felix Kuehling
2021-01-07 3:00 ` [PATCH 03/35] drm/amdkfd: helper to convert gpu id and idx Felix Kuehling
2021-01-07 3:00 ` [PATCH 04/35] drm/amdkfd: add svm ioctl API Felix Kuehling
2021-01-07 3:00 ` [PATCH 05/35] drm/amdkfd: Add SVM API support capability bits Felix Kuehling
2021-01-07 3:00 ` [PATCH 06/35] drm/amdkfd: register svm range Felix Kuehling
2021-01-07 3:00 ` [PATCH 07/35] drm/amdkfd: add svm ioctl GET_ATTR op Felix Kuehling
2021-01-07 3:01 ` [PATCH 08/35] drm/amdgpu: add common HMM get pages function Felix Kuehling
2021-01-07 10:53 ` Christian König
2021-01-07 3:01 ` [PATCH 09/35] drm/amdkfd: validate svm range system memory Felix Kuehling
2021-01-07 3:01 ` [PATCH 10/35] drm/amdkfd: register overlap system memory range Felix Kuehling
2021-01-07 3:01 ` [PATCH 11/35] drm/amdkfd: deregister svm range Felix Kuehling
2021-01-07 3:01 ` [PATCH 12/35] drm/amdgpu: export vm update mapping interface Felix Kuehling
2021-01-07 10:54 ` Christian König
2021-01-07 3:01 ` [PATCH 13/35] drm/amdkfd: map svm range to GPUs Felix Kuehling
2021-01-07 3:01 ` [PATCH 14/35] drm/amdkfd: svm range eviction and restore Felix Kuehling
2021-01-07 3:01 ` [PATCH 15/35] drm/amdkfd: add xnack enabled flag to kfd_process Felix Kuehling
2021-01-07 3:01 ` [PATCH 16/35] drm/amdkfd: add ioctl to configure and query xnack retries Felix Kuehling
2021-01-07 3:01 ` [PATCH 17/35] drm/amdkfd: register HMM device private zone Felix Kuehling
2021-03-01 8:32 ` Daniel Vetter
2021-03-01 8:46 ` Thomas Hellström (Intel)
2021-03-01 8:58 ` Daniel Vetter
2021-03-01 9:30 ` Thomas Hellström (Intel) [this message]
2021-03-04 17:58 ` Felix Kuehling
2021-03-11 12:24 ` Thomas Hellström (Intel)
2021-01-07 3:01 ` [PATCH 18/35] drm/amdkfd: validate vram svm range from TTM Felix Kuehling
2021-01-07 3:01 ` [PATCH 19/35] drm/amdkfd: support xgmi same hive mapping Felix Kuehling
2021-01-07 3:01 ` [PATCH 20/35] drm/amdkfd: copy memory through gart table Felix Kuehling
2021-01-07 3:01 ` [PATCH 21/35] drm/amdkfd: HMM migrate ram to vram Felix Kuehling
2021-01-07 3:01 ` [PATCH 22/35] drm/amdkfd: HMM migrate vram to ram Felix Kuehling
2021-01-07 3:01 ` [PATCH 23/35] drm/amdkfd: invalidate tables on page retry fault Felix Kuehling
2021-01-07 3:01 ` [PATCH 24/35] drm/amdkfd: page table restore through svm API Felix Kuehling
2021-01-07 3:01 ` [PATCH 25/35] drm/amdkfd: SVM API call to restore page tables Felix Kuehling
2021-01-07 3:01 ` [PATCH 26/35] drm/amdkfd: add svm_bo reference for eviction fence Felix Kuehling
2021-01-07 3:01 ` [PATCH 27/35] drm/amdgpu: add param bit flag to create SVM BOs Felix Kuehling
2021-01-07 3:01 ` [PATCH 28/35] drm/amdkfd: add svm_bo eviction mechanism support Felix Kuehling
2021-01-07 3:01 ` [PATCH 29/35] drm/amdgpu: svm bo enable_signal call condition Felix Kuehling
2021-01-07 10:56 ` Christian König
2021-01-07 16:16 ` Felix Kuehling
2021-01-07 16:28 ` Christian König
2021-01-07 16:53 ` Felix Kuehling
2021-01-07 3:01 ` [PATCH 30/35] drm/amdgpu: add svm_bo eviction to enable_signal cb Felix Kuehling
2021-01-07 3:01 ` [PATCH 31/35] drm/amdgpu: reserve fence slot to update page table Felix Kuehling
2021-01-07 10:57 ` Christian König
2021-01-07 3:01 ` [PATCH 32/35] drm/amdgpu: enable retry fault wptr overflow Felix Kuehling
2021-01-07 11:01 ` Christian König
2021-01-07 3:01 ` [PATCH 33/35] drm/amdkfd: refine migration policy with xnack on Felix Kuehling
2021-01-07 3:01 ` [PATCH 34/35] drm/amdkfd: add svm range validate timestamp Felix Kuehling
2021-01-07 3:01 ` [PATCH 35/35] drm/amdkfd: multiple gpu migrate vram to vram Felix Kuehling
2021-01-07 9:23 ` [PATCH 00/35] Add HMM-based SVM memory manager to KFD Daniel Vetter
2021-01-07 16:25 ` Felix Kuehling
2021-01-08 14:40 ` Daniel Vetter
2021-01-08 14:45 ` Christian König
2021-01-08 15:58 ` Felix Kuehling
2021-01-08 16:06 ` Daniel Vetter
2021-01-08 16:36 ` Felix Kuehling
2021-01-08 16:53 ` Daniel Vetter
2021-01-08 17:56 ` Felix Kuehling
2021-01-11 16:29 ` Daniel Vetter
2021-01-14 5:34 ` Felix Kuehling
2021-01-14 12:19 ` Christian König
2021-01-13 16:56 ` Jerome Glisse
2021-01-13 20:31 ` Daniel Vetter
2021-01-14 3:27 ` Jerome Glisse
2021-01-14 9:26 ` Daniel Vetter
2021-01-14 10:39 ` Daniel Vetter
2021-01-14 10:49 ` Christian König
2021-01-14 11:52 ` Daniel Vetter
2021-01-14 13:37 ` HMM fence (was Re: [PATCH 00/35] Add HMM-based SVM memory manager to KFD) Christian König
2021-01-14 13:57 ` Daniel Vetter
2021-01-14 14:13 ` Christian König
2021-01-14 14:23 ` Daniel Vetter
2021-01-14 15:08 ` Christian König
2021-01-14 15:40 ` Daniel Vetter
2021-01-14 16:01 ` Christian König
2021-01-14 16:36 ` Daniel Vetter
2021-01-14 19:08 ` Christian König
2021-01-14 20:09 ` Daniel Vetter
2021-01-14 16:51 ` Jerome Glisse
2021-01-14 21:13 ` Felix Kuehling
2021-01-15 7:47 ` Christian König
2021-01-13 16:47 ` [PATCH 00/35] Add HMM-based SVM memory manager to KFD Jerome Glisse
2021-01-14 0:06 ` Felix Kuehling
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