From: Jonathan Cameron <Jonathan.Cameron@Huawei.com> To: fan <nifan.cxl@gmail.com> Cc: <qemu-devel@nongnu.org>, <linux-cxl@vger.kernel.org>, <gregory.price@memverge.com>, <ira.weiny@intel.com>, <dan.j.williams@intel.com>, <a.manzanares@samsung.com>, <dave@stgolabs.net>, <nmtadam.samsung@gmail.com>, <jim.harris@samsung.com>, <Jorgen.Hansen@wdc.com>, <wj28.lee@gmail.com>, Fan Ni <fan.ni@samsung.com> Subject: Re: [PATCH v5 08/13] hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacity response Date: Thu, 7 Mar 2024 12:20:15 +0000 [thread overview] Message-ID: <20240307122015.00000b6a@Huawei.com> (raw) In-Reply-To: <ZejipnoILw6_Z-Cl@debian> On Wed, 6 Mar 2024 13:39:50 -0800 fan <nifan.cxl@gmail.com> wrote: > > > + } > > > + if (len2) { > > > + cxl_insert_extent_to_extent_list(extent_list, dpa + len, > > > + len2, NULL, 0); > > > + ct3d->dc.total_extent_count += 1; > > > + } > > > + break; > > Maybe this makes sense after the support below is added, but at this > > point in the series > > return CXL_MBOX_SUCCESS; > > then found isn't relevant so can drop that. Looks like you drop it later in the > > series anyway. > > We cannot return directly as we have more extents to release. Ah good point. I'd missed the double loop. > One thing I think I need to add is a dry run to test if any extent in > the income list is not contained by an extent in the extent list and > return error before starting to do the real release. The spec just says > we need to return invalid PA but not specify whether we should update the list > until we found a "bad" extent or reject the request directly. Current code > leaves a situation where we may have updated the extent list until we found a > "bad" extent to release. Yes, I'm not sure on the correct answer to this either. My assumption is that in error cases there are no side effects, but I don't see a clear statement of that. So I think we are in the world of best practice, not spec compliance. If we wanted to recover from such an error case we'd have to verify the current extent list. I'll fire off a question to relevant folk in appropriate forum. Jonathan
WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Cameron via <qemu-devel@nongnu.org> To: fan <nifan.cxl@gmail.com> Cc: <qemu-devel@nongnu.org>, <linux-cxl@vger.kernel.org>, <gregory.price@memverge.com>, <ira.weiny@intel.com>, <dan.j.williams@intel.com>, <a.manzanares@samsung.com>, <dave@stgolabs.net>, <nmtadam.samsung@gmail.com>, <jim.harris@samsung.com>, <Jorgen.Hansen@wdc.com>, <wj28.lee@gmail.com>, Fan Ni <fan.ni@samsung.com> Subject: Re: [PATCH v5 08/13] hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacity response Date: Thu, 7 Mar 2024 12:20:15 +0000 [thread overview] Message-ID: <20240307122015.00000b6a@Huawei.com> (raw) In-Reply-To: <ZejipnoILw6_Z-Cl@debian> On Wed, 6 Mar 2024 13:39:50 -0800 fan <nifan.cxl@gmail.com> wrote: > > > + } > > > + if (len2) { > > > + cxl_insert_extent_to_extent_list(extent_list, dpa + len, > > > + len2, NULL, 0); > > > + ct3d->dc.total_extent_count += 1; > > > + } > > > + break; > > Maybe this makes sense after the support below is added, but at this > > point in the series > > return CXL_MBOX_SUCCESS; > > then found isn't relevant so can drop that. Looks like you drop it later in the > > series anyway. > > We cannot return directly as we have more extents to release. Ah good point. I'd missed the double loop. > One thing I think I need to add is a dry run to test if any extent in > the income list is not contained by an extent in the extent list and > return error before starting to do the real release. The spec just says > we need to return invalid PA but not specify whether we should update the list > until we found a "bad" extent or reject the request directly. Current code > leaves a situation where we may have updated the extent list until we found a > "bad" extent to release. Yes, I'm not sure on the correct answer to this either. My assumption is that in error cases there are no side effects, but I don't see a clear statement of that. So I think we are in the world of best practice, not spec compliance. If we wanted to recover from such an error case we'd have to verify the current extent list. I'll fire off a question to relevant folk in appropriate forum. Jonathan
next prev parent reply other threads:[~2024-03-07 12:20 UTC|newest] Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-04 19:33 [PATCH v5 00/13] Enabling DCD emulation support in Qemu nifan.cxl 2024-03-04 19:33 ` [PATCH v5 01/13] hw/cxl/cxl-mailbox-utils: Add dc_event_log_size field to output payload of identify memory device command nifan.cxl 2024-03-06 15:07 ` Jonathan Cameron 2024-03-06 15:07 ` Jonathan Cameron via 2024-03-04 19:33 ` [PATCH v5 02/13] hw/cxl/cxl-mailbox-utils: Add dynamic capacity region representative and mailbox command support nifan.cxl 2024-03-06 15:24 ` Jonathan Cameron 2024-03-06 15:24 ` Jonathan Cameron via 2024-03-04 19:33 ` [PATCH v5 03/13] include/hw/cxl/cxl_device: Rename mem_size as static_mem_size for type3 memory devices nifan.cxl 2024-03-06 15:39 ` Jonathan Cameron 2024-03-06 15:39 ` Jonathan Cameron via 2024-03-04 19:33 ` [PATCH v5 04/13] hw/mem/cxl_type3: Add support to create DC regions to " nifan.cxl 2024-03-06 15:48 ` Jonathan Cameron 2024-03-06 15:48 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 05/13] hw/mem/cxl-type3: Refactor ct3_build_cdat_entries_for_mr to take mr size insead of mr as argument nifan.cxl 2024-03-06 16:02 ` Jonathan Cameron 2024-03-06 16:02 ` Jonathan Cameron via 2024-03-06 16:03 ` Jonathan Cameron 2024-03-06 16:03 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 06/13] hw/mem/cxl_type3: Add host backend and address space handling for DC regions nifan.cxl 2024-03-06 16:28 ` Jonathan Cameron 2024-03-06 16:28 ` Jonathan Cameron via 2024-03-06 19:14 ` fan 2024-03-07 12:16 ` Jonathan Cameron 2024-03-07 12:16 ` Jonathan Cameron via 2024-03-07 23:34 ` fan 2024-03-14 20:43 ` fan 2024-03-04 19:34 ` [PATCH v5 07/13] hw/mem/cxl_type3: Add DC extent list representative and get DC extent list mailbox support nifan.cxl 2024-03-06 16:37 ` Jonathan Cameron 2024-03-06 16:37 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 08/13] hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacity response nifan.cxl 2024-03-06 17:28 ` Jonathan Cameron 2024-03-06 17:28 ` Jonathan Cameron via 2024-03-06 21:39 ` fan 2024-03-07 12:20 ` Jonathan Cameron [this message] 2024-03-07 12:20 ` Jonathan Cameron via 2024-03-06 22:34 ` fan 2024-03-07 12:30 ` Jonathan Cameron 2024-03-07 12:30 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 09/13] hw/cxl/events: Add qmp interfaces to add/release dynamic capacity extents nifan.cxl 2024-03-06 17:48 ` Jonathan Cameron 2024-03-06 17:48 ` Jonathan Cameron via 2024-03-06 23:15 ` fan 2024-03-07 12:45 ` Jonathan Cameron 2024-03-07 12:45 ` Jonathan Cameron via 2024-03-09 4:35 ` fan 2024-03-12 12:37 ` Jonathan Cameron 2024-03-12 12:37 ` Jonathan Cameron via 2024-03-12 16:27 ` fan 2024-03-06 23:36 ` fan 2024-03-07 12:47 ` Jonathan Cameron 2024-03-07 12:47 ` Jonathan Cameron via 2024-04-24 13:09 ` Markus Armbruster 2024-04-24 17:10 ` fan 2024-04-24 17:26 ` Markus Armbruster 2024-04-24 17:44 ` fan 2024-04-24 17:33 ` Ira Weiny 2024-04-26 15:55 ` Jonathan Cameron 2024-04-26 15:55 ` Jonathan Cameron via 2024-04-26 16:22 ` Gregory Price 2024-04-24 17:39 ` fan 2024-04-25 5:48 ` Markus Armbruster 2024-04-25 17:30 ` Ira Weiny 2024-04-26 16:00 ` Jonathan Cameron 2024-04-26 16:00 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 10/13] hw/mem/cxl_type3: Add dpa range validation for accesses to DC regions nifan.cxl 2024-03-06 17:50 ` Jonathan Cameron 2024-03-06 17:50 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 11/13] hw/cxl/cxl-mailbox-utils: Add partial and superset extent release mailbox support nifan.cxl 2024-03-06 18:09 ` Jonathan Cameron 2024-03-06 18:09 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 12/13] hw/mem/cxl_type3: Allow to release partial extent and extent superset in QMP interface nifan.cxl 2024-03-06 18:14 ` Jonathan Cameron 2024-03-06 18:14 ` Jonathan Cameron via 2024-03-04 19:34 ` [PATCH v5 13/13] qapi/cxl.json: Add QMP interfaces to print out accepted and pending DC extents nifan.cxl 2024-03-05 16:09 ` Jonathan Cameron 2024-03-05 16:09 ` Jonathan Cameron via 2024-03-05 16:15 ` Daniel P. Berrangé 2024-03-05 17:09 ` fan 2024-03-05 17:14 ` Daniel P. Berrangé 2024-04-24 13:12 ` Markus Armbruster 2024-04-24 17:12 ` fan
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