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From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: <linux-cxl@vger.kernel.org>, <ira.weiny@intel.com>,
	<navneet.singh@intel.com>
Subject: Re: [PATCH 15/19] cxl/region: Specify host-only vs device memory at region creation time
Date: Tue, 6 Jun 2023 15:42:55 +0100	[thread overview]
Message-ID: <20230606154255.00003a7f@Huawei.com> (raw)
In-Reply-To: <168592158192.1948938.1274727683021213802.stgit@dwillia2-xfh.jf.intel.com>

On Sun, 04 Jun 2023 16:33:01 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> In preparation for supporting device-memory (HDM-D[B]) region creation,
> convey the endpoint-decoder target type to devm_cxl_add_region().
> 
> Note that none of the existing sysfs ABIs allow for HDM-D[B] region
> creation. The expectation is that HDM-D[B] region creation requires a
> kernel-internal region creation flow, for example, driven by an
> accelerator driver.

There are potential advantages in using CXL type 3 HDM-DB devices with
a normal flow, userspace driven region creation flow.  If there is
any potential for UIO P2P transactions targeting them later (which
we won't necessarily know at setup time) then we'll need to use HDM-DB.
 The targetting of them for UIO will require some accelerator specific
stuff at the source of the transactions, but we won't want to offline
the memory on a type 3 device to convert it over to HDM-H
(assuming that's required...)

+ cache coherent sharing - though I guess region setup code may
be quite different for that anyway :)  I've not divided into
Navneet's set yet to see how he did it.

Code itself is fine - just the comment potentially being misleading or
overly restrictive.

Jonathan

  reply	other threads:[~2023-06-06 14:46 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-04 23:31 [PATCH 00/19] cxl: Device memory setup Dan Williams
2023-06-04 23:31 ` [PATCH 01/19] cxl/regs: Clarify when a 'struct cxl_register_map' is input vs output Dan Williams
2023-06-05  8:46   ` Jonathan Cameron
2023-06-13 22:03   ` Dave Jiang
2023-06-04 23:31 ` [PATCH 02/19] tools/testing/cxl: Remove unused @cxlds argument Dan Williams
2023-06-06 10:53   ` Jonathan Cameron
2023-06-13 22:08   ` Dave Jiang
2023-06-04 23:31 ` [PATCH 03/19] cxl/mbox: Move mailbox related driver state to its own data structure Dan Williams
2023-06-06 11:10   ` Jonathan Cameron
2023-06-14  0:45     ` Dan Williams
2023-06-13 22:15   ` Dave Jiang
2023-06-04 23:31 ` [PATCH 04/19] cxl/memdev: Make mailbox functionality optional Dan Williams
2023-06-06 11:15   ` Jonathan Cameron
2023-06-13 20:53     ` Dan Williams
2023-06-04 23:32 ` [PATCH 05/19] cxl/port: Rename CXL_DECODER_{EXPANDER, ACCELERATOR} => {HOSTMEM, DEVMEM} Dan Williams
2023-06-06 11:21   ` Jonathan Cameron
2023-06-13 21:03     ` Dan Williams
2023-06-04 23:32 ` [PATCH 06/19] cxl/hdm: Default CXL_DEVTYPE_DEVMEM decoders to CXL_DECODER_DEVMEM Dan Williams
2023-06-05  1:14   ` kernel test robot
2023-06-06 20:10     ` Dan Williams
2023-06-06 11:27   ` Jonathan Cameron
2023-06-13 21:23     ` Dan Williams
2023-06-13 22:32     ` Dan Williams
2023-06-14  9:15       ` Jonathan Cameron
2023-06-04 23:32 ` [PATCH 07/19] cxl/region: Manage decoder target_type at decoder-attach time Dan Williams
2023-06-06 12:36   ` Jonathan Cameron
2023-06-13 22:42   ` Dave Jiang
2023-06-04 23:32 ` [PATCH 08/19] cxl/port: Enumerate flit mode capability Dan Williams
2023-06-06 13:04   ` Jonathan Cameron
2023-06-14  1:06     ` Dan Williams
2023-06-04 23:32 ` [PATCH 09/19] cxl/memdev: Formalize endpoint port linkage Dan Williams
2023-06-06 13:26   ` Jonathan Cameron
     [not found]   ` <CGME20230607164756uscas1p2fb025e7f4de5094925cc25fc2ac45212@uscas1p2.samsung.com>
2023-06-07 16:47     ` Fan Ni
2023-06-13 22:59   ` Dave Jiang
2023-06-04 23:32 ` [PATCH 10/19] cxl/memdev: Indicate probe deferral Dan Williams
2023-06-06 13:54   ` Jonathan Cameron
2023-06-04 23:32 ` [PATCH 11/19] cxl/region: Factor out construct_region_{begin, end} and drop_region() for reuse Dan Williams
2023-06-06 14:29   ` Jonathan Cameron
2023-06-13 23:29   ` Dave Jiang
2023-06-04 23:32 ` [PATCH 12/19] cxl/region: Factor out interleave ways setup Dan Williams
2023-06-06 14:31   ` Jonathan Cameron
2023-06-13 23:30   ` Dave Jiang
2023-06-04 23:32 ` [PATCH 13/19] cxl/region: Factor out interleave granularity setup Dan Williams
2023-06-06 14:33   ` Jonathan Cameron
2023-06-13 23:42   ` Dave Jiang
2023-06-04 23:32 ` [PATCH 14/19] cxl/region: Clarify locking requirements of cxl_region_attach() Dan Williams
2023-06-06 14:35   ` Jonathan Cameron
2023-06-13 23:45   ` Dave Jiang
2023-06-04 23:33 ` [PATCH 15/19] cxl/region: Specify host-only vs device memory at region creation time Dan Williams
2023-06-06 14:42   ` Jonathan Cameron [this message]
2023-06-04 23:33 ` [PATCH 16/19] cxl/hdm: Define a driver interface for DPA allocation Dan Williams
2023-06-06 14:58   ` Jonathan Cameron
2023-06-13 23:53   ` Dave Jiang
2023-06-04 23:33 ` [PATCH 17/19] cxl/region: Define a driver interface for HPA free space enumeration Dan Williams
2023-06-06 15:23   ` Jonathan Cameron
2023-06-14  0:15   ` Dave Jiang
2023-06-04 23:33 ` [PATCH 18/19] cxl/region: Define a driver interface for region creation Dan Williams
2023-06-06 15:31   ` Jonathan Cameron
2023-06-04 23:33 ` [PATCH 19/19] tools/testing/cxl: Emulate a CXL accelerator with local memory Dan Williams
2023-06-06 15:34   ` Jonathan Cameron
2023-06-07 21:09   ` Vikram Sethi
2023-06-08 10:47     ` Jonathan Cameron
2023-06-08 14:34       ` Vikram Sethi
2023-06-08 15:22         ` Jonathan Cameron

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