| Message ID | 20241007-dcd-type2-upstream-v4-25-c261ee6eeded@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | DCD: Add support for Dynamic Capacity Devices (DCD) | expand |
On Mon, 07 Oct 2024 18:16:31 -0500 ira.weiny@intel.com wrote: > From: Navneet Singh <navneet.singh@intel.com> > > Dynamic capacity device extents may be left in an accepted state on a > device due to an unexpected host crash. In this case it is expected > that the creation of a new region on top of a DC partition can read > those extents and surface them for continued use. > > Once all endpoint decoders are part of a region and the region is being > realized, a read of the 'devices extent list' can reveal these > previously accepted extents. > > CXL r3.1 specifies the mailbox call Get Dynamic Capacity Extent List for > this purpose. The call returns all the extents for all dynamic capacity > partitions. If the fabric manager is adding extents to any DCD > partition, the extent list for the recovered region may change. In this > case the query must retry. Upon retry the query could encounter extents > which were accepted on a previous list query. Adding such extents is > ignored without error because they are entirely within a previous > accepted extent. > > The scan for existing extents races with the dax_cxl driver. This is > synchronized through the region device lock. Extents which are found > after the driver has loaded will surface through the normal notification > path while extents seen prior to the driver are read during driver load. > > Signed-off-by: Navneet Singh <navneet.singh@intel.com> > Co-developed-by: Ira Weiny <ira.weiny@intel.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > One buglet, and a request for an error message. With those. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > index d66beec687a0..6b25d15403a3 100644 > --- a/drivers/cxl/core/mbox.c > +++ b/drivers/cxl/core/mbox.c > @@ -1697,6 +1697,111 @@ int cxl_dev_dynamic_capacity_identify(struct cxl_memdev_state *mds) > } > EXPORT_SYMBOL_NS_GPL(cxl_dev_dynamic_capacity_identify, CXL); > > +/* Return -EAGAIN if the extent list changes while reading */ > +static int __cxl_process_extent_list(struct cxl_endpoint_decoder *cxled) > +{ > + u32 current_index, total_read, total_expected, initial_gen_num; > + struct cxl_memdev_state *mds = cxled_to_mds(cxled); > + struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox; > + struct device *dev = mds->cxlds.dev; > + struct cxl_mbox_cmd mbox_cmd; > + u32 max_extent_count; > + bool first = true; > + > + struct cxl_mbox_get_extent_out *extents __free(kfree) = __free(kvfree) > + kvmalloc(cxl_mbox->payload_size, GFP_KERNEL); > + if (!extents) > + return -ENOMEM; ... > +} > static void cxlr_dax_unregister(void *_cxlr_dax) > { > struct cxl_dax_region *cxlr_dax = _cxlr_dax; > @@ -3224,6 +3233,9 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr) > dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent), > dev_name(dev)); > > + if (cxlr->mode == CXL_REGION_DC) > + cxlr_add_existing_extents(cxlr); Whilst there isn't a whole lot we can do if this fails, I'd like an error print to indicate something odd is going on. Probably pass any error up to here then print a message before carrying on. > + > return devm_add_action_or_reset(&cxlr->dev, cxlr_dax_unregister, > cxlr_dax); > err:
Jonathan Cameron wrote: > On Mon, 07 Oct 2024 18:16:31 -0500 > ira.weiny@intel.com wrote: > > > From: Navneet Singh <navneet.singh@intel.com> > > [snip] > > > One buglet, and a request for an error message. > With those. > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Thanks. > > > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > > index d66beec687a0..6b25d15403a3 100644 > > --- a/drivers/cxl/core/mbox.c > > +++ b/drivers/cxl/core/mbox.c > > @@ -1697,6 +1697,111 @@ int cxl_dev_dynamic_capacity_identify(struct cxl_memdev_state *mds) > > } > > EXPORT_SYMBOL_NS_GPL(cxl_dev_dynamic_capacity_identify, CXL); > > > > +/* Return -EAGAIN if the extent list changes while reading */ > > +static int __cxl_process_extent_list(struct cxl_endpoint_decoder *cxled) > > +{ > > + u32 current_index, total_read, total_expected, initial_gen_num; > > + struct cxl_memdev_state *mds = cxled_to_mds(cxled); > > + struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox; > > + struct device *dev = mds->cxlds.dev; > > + struct cxl_mbox_cmd mbox_cmd; > > + u32 max_extent_count; > > + bool first = true; > > + > > + struct cxl_mbox_get_extent_out *extents __free(kfree) = > > __free(kvfree) Yep fixed > > > + kvmalloc(cxl_mbox->payload_size, GFP_KERNEL); > > + if (!extents) > > + return -ENOMEM; > > ... > > > > +} > > > static void cxlr_dax_unregister(void *_cxlr_dax) > > { > > struct cxl_dax_region *cxlr_dax = _cxlr_dax; > > @@ -3224,6 +3233,9 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr) > > dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent), > > dev_name(dev)); > > > > + if (cxlr->mode == CXL_REGION_DC) > > + cxlr_add_existing_extents(cxlr); > > Whilst there isn't a whole lot we can do if this fails, I'd like an error > print to indicate something odd is going on. Probably pass any error > up to here then print a message before carrying on. Bubbled up an error and added some dev_err() calls. I don't think they need to be rate limited since regions are not created very often. Ira [snip]
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h index 0eccdd0b9261..80d61f75161d 100644 --- a/drivers/cxl/core/core.h +++ b/drivers/cxl/core/core.h @@ -21,6 +21,8 @@ cxled_to_mds(struct cxl_endpoint_decoder *cxled) return container_of(cxlds, struct cxl_memdev_state, cxlds); } +void cxl_process_extent_list(struct cxl_endpoint_decoder *cxled); + #ifdef CONFIG_CXL_REGION extern struct device_attribute dev_attr_create_pmem_region; extern struct device_attribute dev_attr_create_ram_region; diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index d66beec687a0..6b25d15403a3 100644 --- a/drivers/cxl/core/mbox.c +++ b/drivers/cxl/core/mbox.c @@ -1697,6 +1697,111 @@ int cxl_dev_dynamic_capacity_identify(struct cxl_memdev_state *mds) } EXPORT_SYMBOL_NS_GPL(cxl_dev_dynamic_capacity_identify, CXL); +/* Return -EAGAIN if the extent list changes while reading */ +static int __cxl_process_extent_list(struct cxl_endpoint_decoder *cxled) +{ + u32 current_index, total_read, total_expected, initial_gen_num; + struct cxl_memdev_state *mds = cxled_to_mds(cxled); + struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox; + struct device *dev = mds->cxlds.dev; + struct cxl_mbox_cmd mbox_cmd; + u32 max_extent_count; + bool first = true; + + struct cxl_mbox_get_extent_out *extents __free(kfree) = + kvmalloc(cxl_mbox->payload_size, GFP_KERNEL); + if (!extents) + return -ENOMEM; + + total_read = 0; + current_index = 0; + total_expected = 0; + max_extent_count = (cxl_mbox->payload_size - sizeof(*extents)) / + sizeof(struct cxl_extent); + do { + struct cxl_mbox_get_extent_in get_extent; + u32 nr_returned, current_total, current_gen_num; + int rc; + + get_extent = (struct cxl_mbox_get_extent_in) { + .extent_cnt = max(max_extent_count, + total_expected - current_index), + .start_extent_index = cpu_to_le32(current_index), + }; + + mbox_cmd = (struct cxl_mbox_cmd) { + .opcode = CXL_MBOX_OP_GET_DC_EXTENT_LIST, + .payload_in = &get_extent, + .size_in = sizeof(get_extent), + .size_out = cxl_mbox->payload_size, + .payload_out = extents, + .min_out = 1, + }; + + rc = cxl_internal_send_cmd(cxl_mbox, &mbox_cmd); + if (rc < 0) + return rc; + + /* Save initial data */ + if (first) { + total_expected = le32_to_cpu(extents->total_extent_count); + initial_gen_num = le32_to_cpu(extents->generation_num); + first = false; + } + + nr_returned = le32_to_cpu(extents->returned_extent_count); + total_read += nr_returned; + current_total = le32_to_cpu(extents->total_extent_count); + current_gen_num = le32_to_cpu(extents->generation_num); + + dev_dbg(dev, "Got extent list %d-%d of %d generation Num:%d\n", + current_index, total_read - 1, current_total, current_gen_num); + + if (current_gen_num != initial_gen_num || total_expected != current_total) { + dev_dbg(dev, "Extent list change detected; gen %u != %u : cnt %u != %u\n", + current_gen_num, initial_gen_num, + total_expected, current_total); + return -EAGAIN; + } + + for (int i = 0; i < nr_returned ; i++) { + struct cxl_extent *extent = &extents->extent[i]; + + dev_dbg(dev, "Processing extent %d/%d\n", + current_index + i, total_expected); + + rc = validate_add_extent(mds, extent); + if (rc) + continue; + } + + current_index += nr_returned; + } while (total_expected > total_read); + + return 0; +} + +/** + * cxl_process_extent_list() - Read existing extents + * @cxled: Endpoint decoder which is part of a region + * + * Issue the Get Dynamic Capacity Extent List command to the device + * and add existing extents if found. + * + * A retry of 10 is somewhat arbitrary, however, extent changes should be + * relatively rare while bringing up a region. So 10 should be plenty. + */ +#define CXL_READ_EXTENT_LIST_RETRY 10 +void cxl_process_extent_list(struct cxl_endpoint_decoder *cxled) +{ + int retry = CXL_READ_EXTENT_LIST_RETRY; + int rc; + + do { + rc = __cxl_process_extent_list(cxled); + } while (rc == -EAGAIN && retry--); +} + static int add_dpa_res(struct device *dev, struct resource *parent, struct resource *res, resource_size_t start, resource_size_t size, const char *type) diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 6ae51fc2bdae..5ed4a77491e5 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -3190,6 +3190,15 @@ static int devm_cxl_add_pmem_region(struct cxl_region *cxlr) return rc; } +static void cxlr_add_existing_extents(struct cxl_region *cxlr) +{ + struct cxl_region_params *p = &cxlr->params; + int i; + + for (i = 0; i < p->nr_targets; i++) + cxl_process_extent_list(p->targets[i]); +} + static void cxlr_dax_unregister(void *_cxlr_dax) { struct cxl_dax_region *cxlr_dax = _cxlr_dax; @@ -3224,6 +3233,9 @@ static int devm_cxl_add_dax_region(struct cxl_region *cxlr) dev_dbg(&cxlr->dev, "%s: register %s\n", dev_name(dev->parent), dev_name(dev)); + if (cxlr->mode == CXL_REGION_DC) + cxlr_add_existing_extents(cxlr); + return devm_add_action_or_reset(&cxlr->dev, cxlr_dax_unregister, cxlr_dax); err: diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index dd7cc0d373af..4272f134da8f 100644 --- a/drivers/cxl/cxlmem.h +++ b/drivers/cxl/cxlmem.h @@ -626,6 +626,27 @@ struct cxl_mbox_dc_response { } __packed extent_list[]; } __packed; +/* + * Get Dynamic Capacity Extent List; Input Payload + * CXL rev 3.1 section 8.2.9.9.9.2; Table 8-166 + */ +struct cxl_mbox_get_extent_in { + __le32 extent_cnt; + __le32 start_extent_index; +} __packed; + +/* + * Get Dynamic Capacity Extent List; Output Payload + * CXL rev 3.1 section 8.2.9.9.9.2; Table 8-167 + */ +struct cxl_mbox_get_extent_out { + __le32 returned_extent_count; + __le32 total_extent_count; + __le32 generation_num; + u8 rsvd[4]; + struct cxl_extent extent[]; +} __packed; + struct cxl_mbox_get_supported_logs { __le16 entries; u8 rsvd[6];