Messages in this thread | | | Date | Fri, 17 Jun 2022 18:35:49 -0700 | From | Alison Schofield <> | Subject | Re: [PATCH 3/3] cxl/core: Add sysfs attribute get_poison for list retrieval |
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On Fri, Jun 17, 2022 at 06:08:52PM -0700, Dan Williams wrote: > Alison Schofield wrote: > > On Fri, Jun 17, 2022 at 11:42:11AM -0700, Dan Williams wrote: > > > alison.schofield@ wrote: > > > > From: Alison Schofield <alison.schofield@intel.com> > > > > > > > > The sysfs attribute, get_poison, allows user space to request the > > > > retrieval of a CXL devices poison list for its persistent memory. > > > > > > If the device supports get poison list for volatile memory, just grab > > > that too. With the "to be released soon" region patches userspace can > > > trivially translate DPA addresses to media type. > > > > > > > Dan, > > > > The only way I know to discover if the device supports poison list for > > volatile is to do the get_poison_list on the volatile range and see > > what happens. Am I missing a capability setting somewhere? > > If someone executes "echo 1 > trace_poison_list" I expect that the > driver does: > > get_poison_list(volatile_range); > get_poison_list(pmem_range); > > ...and if scanning the volatile partition ends in error then that just > means no error records appear. When the error is "Invalid Physical > Address" the driver can just remember that's a permanent error and never > try again. So it's more like: > > if (volatile_range_valid) { > if (get_poison_list(volatile_range) == INVALID_PHYS_ADDR) > volatile_range_valid = false; > } > get_poison_list(pmem_range); > > ...but that's probably overkill since get_poison_list() is cheap. Just > treat it like the zero error records case.
Got it!
> > In the to be released region provisioning patches there is a DPA > resource tree partitioned by DPA mode type, so the poison list code > probably wants to do something like: > > down_read(&cxl_dpa_rwsem); > for (p = cxlds->dpa_res.child; p; p = p->sibling) > get_poison_list(p->start, resource_size(p)); > up_read(&cxl_dpa_rwsem);
Great ending to the week! This is going to make collecting the poison per region much simpler than I was imagining :)
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