From: Christoph Hellwig <hch@infradead.org>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Xiaoming Ding <xiaoming.ding@mediatek.com>,
Jens Wiklander <jens.wiklander@linaro.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
op-tee@lists.trustedfirmware.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, fei.xu@mediatek.com,
srv_heupstream@mediatek.com, linux-mm@kvack.org
Subject: Re: [PATCH] tee: add FOLL_LONGTERM for CMA case when alloc shm
Date: Wed, 17 May 2023 02:36:09 -0700 [thread overview]
Message-ID: <ZGSgCZrg+RjAbGO1@infradead.org> (raw)
In-Reply-To: <CAFA6WYPOMwmrA3J84AHzoD2eAtNkpMxr754qHpc-j6XRkgFFvQ@mail.gmail.com>
On Wed, May 17, 2023 at 02:56:13PM +0530, Sumit Garg wrote:
> Do you mean a pinned user-space page can be paged out automatically?
No, pinned pages can't be paged out.
But a short term pin implies it will be release after a short delay,
and it is feasible for wait for the pin to go away.
For a long term pin waiting is not an option, and anyone wanting to
do something with the pinned page that requires it to not be pinned
must simply give up.
> Just FYI, the underlying use-case for TEE registered shared memory is
> that the references to pinned pages are provided to TEE implementation
> to operate upon. This can happen over multiple syscalls and we want
> the pinned pages to be always in RAM as otherwise the physical
> addresses may change if they are paged out in between.
That's a very use clear case for a long term pin.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: op-tee@lists.trustedfirmware.org
Subject: Re: [PATCH] tee: add FOLL_LONGTERM for CMA case when alloc shm
Date: Wed, 17 May 2023 02:36:09 -0700 [thread overview]
Message-ID: <ZGSgCZrg+RjAbGO1@infradead.org> (raw)
In-Reply-To: < <CAFA6WYPOMwmrA3J84AHzoD2eAtNkpMxr754qHpc-j6XRkgFFvQ@mail.gmail.com>>
[-- Attachment #1: Type: text/plain, Size: 838 bytes --]
On Wed, May 17, 2023 at 02:56:13PM +0530, Sumit Garg wrote:
> Do you mean a pinned user-space page can be paged out automatically?
No, pinned pages can't be paged out.
But a short term pin implies it will be release after a short delay,
and it is feasible for wait for the pin to go away.
For a long term pin waiting is not an option, and anyone wanting to
do something with the pinned page that requires it to not be pinned
must simply give up.
> Just FYI, the underlying use-case for TEE registered shared memory is
> that the references to pinned pages are provided to TEE implementation
> to operate upon. This can happen over multiple syscalls and we want
> the pinned pages to be always in RAM as otherwise the physical
> addresses may change if they are paged out in between.
That's a very use clear case for a long term pin.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Xiaoming Ding <xiaoming.ding@mediatek.com>,
Jens Wiklander <jens.wiklander@linaro.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
op-tee@lists.trustedfirmware.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, fei.xu@mediatek.com,
srv_heupstream@mediatek.com, linux-mm@kvack.org
Subject: Re: [PATCH] tee: add FOLL_LONGTERM for CMA case when alloc shm
Date: Wed, 17 May 2023 02:36:09 -0700 [thread overview]
Message-ID: <ZGSgCZrg+RjAbGO1@infradead.org> (raw)
In-Reply-To: <CAFA6WYPOMwmrA3J84AHzoD2eAtNkpMxr754qHpc-j6XRkgFFvQ@mail.gmail.com>
On Wed, May 17, 2023 at 02:56:13PM +0530, Sumit Garg wrote:
> Do you mean a pinned user-space page can be paged out automatically?
No, pinned pages can't be paged out.
But a short term pin implies it will be release after a short delay,
and it is feasible for wait for the pin to go away.
For a long term pin waiting is not an option, and anyone wanting to
do something with the pinned page that requires it to not be pinned
must simply give up.
> Just FYI, the underlying use-case for TEE registered shared memory is
> that the references to pinned pages are provided to TEE implementation
> to operate upon. This can happen over multiple syscalls and we want
> the pinned pages to be always in RAM as otherwise the physical
> addresses may change if they are paged out in between.
That's a very use clear case for a long term pin.
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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-05-17 9:36 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-17 3:18 [PATCH] tee: add FOLL_LONGTERM for CMA case when alloc shm Xiaoming Ding
2023-05-17 3:18 ` Xiaoming Ding
2023-05-17 3:18 ` Xiaoming Ding
2023-05-17 7:34 ` Christoph Hellwig
2023-05-17 7:34 ` Christoph Hellwig
2023-05-17 7:34 ` Christoph Hellwig
2023-05-17 7:52 ` Sumit Garg
2023-05-17 7:52 ` Sumit Garg
2023-05-17 7:52 ` Sumit Garg
2023-05-17 8:08 ` Christoph Hellwig
2023-05-17 8:08 ` Christoph Hellwig
2023-05-17 8:08 ` Christoph Hellwig
2023-05-17 9:02 ` Xiaoming Ding (丁晓明)
2023-05-17 9:02 ` Xiaoming Ding (丁晓明)
2023-05-17 9:26 ` Sumit Garg
2023-05-17 9:26 ` Sumit Garg
2023-05-17 9:26 ` Sumit Garg
2023-05-17 9:36 ` Christoph Hellwig [this message]
2023-05-17 9:36 ` Christoph Hellwig
2023-05-17 9:36 ` Christoph Hellwig
2023-05-17 10:19 ` Sumit Garg
2023-05-17 10:19 ` Sumit Garg
2023-05-17 10:19 ` Sumit Garg
2023-05-17 18:23 ` David Hildenbrand
2023-05-17 18:23 ` David Hildenbrand
2023-05-17 18:23 ` David Hildenbrand
2023-05-18 4:20 ` FOLL_LONGTERM vs FOLL_EPHEMERAL " Christoph Hellwig
2023-05-18 4:20 ` Christoph Hellwig
2023-05-18 4:20 ` Christoph Hellwig
2023-05-18 6:08 ` Sumit Garg
2023-05-18 6:08 ` Sumit Garg
2023-05-18 6:08 ` Sumit Garg
2023-05-18 13:56 ` David Hildenbrand
2023-05-18 13:56 ` David Hildenbrand
2023-05-18 13:56 ` David Hildenbrand
2023-05-23 1:54 ` John Hubbard
2023-05-23 1:54 ` John Hubbard
2023-05-23 1:54 ` John Hubbard
2023-05-23 7:25 ` Lorenzo Stoakes
2023-05-23 7:25 ` Lorenzo Stoakes
2023-05-23 7:25 ` Lorenzo Stoakes
2023-06-13 5:30 ` Xiaoming Ding (丁晓明)
2023-06-13 5:30 ` Xiaoming Ding (丁晓明)
2023-06-13 8:48 ` Sumit Garg
2023-06-13 8:48 ` Sumit Garg
2023-06-13 8:48 ` Sumit Garg
2023-05-18 6:40 ` Xiaoming Ding (丁晓明)
2023-05-18 6:40 ` Xiaoming Ding (丁晓明)
2023-05-19 10:01 ` David Hildenbrand
2023-05-19 10:01 ` David Hildenbrand
2023-05-19 10:01 ` David Hildenbrand
2023-05-19 11:03 ` Sumit Garg
2023-05-19 11:03 ` Sumit Garg
2023-05-19 11:03 ` Sumit Garg
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