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[73.170.217.179]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d04ae5abaesm2708425ad.27.2026.07.31.01.49.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Jul 2026 01:49:33 -0700 (PDT) From: Anisa Su X-Google-Original-From: Anisa Su To: linux-cxl@vger.kernel.org Cc: nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, Dave Jiang , Alison Schofield , Jonathan Cameron , Fan Ni , Li Ming , Vishal Verma , Davidlohr Bueso , Ira Weiny , Benjamin Cheatham , Wonjae Lee , Junhee Park , Heesoo Kim , Anisa Su Subject: [PATCH v12 2/8] cxl/mem: Read dynamic capacity configuration from the device Date: Fri, 31 Jul 2026 01:48:07 -0700 Message-ID: <20260731084901.1512819-3-anisa.su@samsung.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260731084901.1512819-1-anisa.su@samsung.com> References: <20260731084901.1512819-1-anisa.su@samsung.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ira Weiny Devices which optionally support Dynamic Capacity (DC) are configured via mailbox commands. CXL r4.0 section 9.13.3 requires the host to issue the Get DC Configuration command in order to properly configure DCDs. Without the Get DC Configuration command DCD can't be supported. Implement the DC mailbox commands as specified in CXL 4.0 section 8.2.10.9.9 (opcodes 48XXh) to read and store the DCD configuration information. Disable DCD if an invalid configuration is found. Linux has no support for more than one dynamic capacity partition. Read and validate all the partitions but configure only the first partition as 'dynamic ram 1'. Additional partitions can be added in the future if such a device ever materializes. Additionally it is anticipated that no skips will be present from the end of the pmem partition. Check for and disallow this configuration as well. Based on an original patch by Navneet Singh. Signed-off-by: Ira Weiny Signed-off-by: Anisa Su Tested-by: Wonjae Lee Tested-by: Junhee Park Tested-by: Heesoo Kim --- Changes: 1. mbox.c: bound the Get DC Config request by the negotiated mailbox payload. Requesting all CXL_MAX_DC_PARTITIONS (8) needs a 328-byte response, which exceeds a spec-minimum 256-byte mailbox and fails -E2BIG, disabling DCD. Cap partition_count per call to what the payload holds and read the rest via the existing start_partition loop. --- drivers/cxl/core/hdm.c | 2 + drivers/cxl/core/mbox.c | 220 ++++++++++++++++++++++++++++++++++++++++ drivers/cxl/cxlmem.h | 55 ++++++++++ drivers/cxl/pci.c | 3 + include/cxl/cxl.h | 3 +- 5 files changed, 282 insertions(+), 1 deletion(-) diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c index 0c80b76a5f9b..0ef076c08ed2 100644 --- a/drivers/cxl/core/hdm.c +++ b/drivers/cxl/core/hdm.c @@ -446,6 +446,8 @@ static const char *cxl_mode_name(enum cxl_partition_mode mode) return "ram"; case CXL_PARTMODE_PMEM: return "pmem"; + case CXL_PARTMODE_DYNAMIC_RAM_1: + return "dynamic_ram_1"; default: return ""; }; diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c index 4790524c32a7..d79019fbd790 100644 --- a/drivers/cxl/core/mbox.c +++ b/drivers/cxl/core/mbox.c @@ -1352,6 +1352,197 @@ int cxl_mem_sanitize(struct cxl_memdev *cxlmd, u16 cmd) return -EBUSY; } +static int cxl_dc_check(struct device *dev, struct cxl_dc_partition_info *part_array, + u8 index, struct cxl_dc_partition *dev_part) +{ + u64 blk_size = le64_to_cpu(dev_part->block_size); + u64 len = le64_to_cpu(dev_part->length); + + part_array[index].start = le64_to_cpu(dev_part->base); + part_array[index].size = le64_to_cpu(dev_part->decode_length); + part_array[index].size *= CXL_CAPACITY_MULTIPLIER; + + /* Check partitions are in increasing DPA order */ + if (index > 0) { + struct cxl_dc_partition_info *prev_part = &part_array[index - 1]; + + if ((prev_part->start + prev_part->size) > + part_array[index].start) { + dev_err(dev, + "DPA ordering violation for DC partition %d and %d\n", + index - 1, index); + return -EINVAL; + } + } + + if (part_array[index].size == 0 || len == 0 || + part_array[index].size < len || !IS_ALIGNED(len, blk_size)) { + dev_err(dev, "DC partition %d invalid length; size %llu len %llu blk size %llu\n", + index, part_array[index].size, len, blk_size); + return -EINVAL; + } + + if (blk_size == 0 || blk_size % CXL_DCD_BLOCK_LINE_SIZE || + !is_power_of_2(blk_size)) { + dev_err(dev, "DC partition %d invalid block size %llu\n", + index, blk_size); + return -EINVAL; + } + + if (!IS_ALIGNED(part_array[index].start, SZ_256M) || + !IS_ALIGNED(part_array[index].start, blk_size)) { + dev_err(dev, "DC partition %d invalid start %llu blk size %llu\n", + index, part_array[index].start, blk_size); + return -EINVAL; + } + + dev_dbg(dev, "DC partition %d start %llu size %llu blk_size: %llu\n", + index, part_array[index].start, part_array[index].size, + blk_size); + + return 0; +} + +/* Returns the number of partitions in dc_resp or -ERRNO */ +static int cxl_get_dc_config(struct cxl_mailbox *mbox, u8 start_partition, + u8 partition_count, + struct cxl_mbox_get_dc_config_out *dc_resp, + size_t dc_resp_size) +{ + struct cxl_mbox_get_dc_config_in get_dc = (struct cxl_mbox_get_dc_config_in) { + .partition_count = partition_count, + .start_partition_index = start_partition, + }; + struct cxl_mbox_cmd mbox_cmd = (struct cxl_mbox_cmd) { + .opcode = CXL_MBOX_OP_GET_DC_CONFIG, + .payload_in = &get_dc, + .size_in = sizeof(get_dc), + .size_out = dc_resp_size, + .payload_out = dc_resp, + .min_out = 8, + }; + size_t expected_sz; + int rc; + + rc = cxl_internal_send_cmd(mbox, &mbox_cmd); + if (rc < 0) + return rc; + + if (dc_resp->partitions_returned > partition_count) { + dev_err(mbox->host, "Device returned %u partitions, requested %u\n", + dc_resp->partitions_returned, partition_count); + return -EIO; + } + + /* + * The payload carries trailing extent/tag count fields after the + * partition array (CXL r4.0 Table 8-179) which the driver ignores, so + * the response is at least, not exactly, expected_sz. + */ + expected_sz = struct_size(dc_resp, partition, + dc_resp->partitions_returned); + + if (mbox_cmd.size_out < expected_sz) { + dev_err(mbox->host, + "Payload size %zu less than expected %zu for %u partitions\n", + mbox_cmd.size_out, + expected_sz, + dc_resp->partitions_returned); + return -EIO; + } + + dev_dbg(mbox->host, "Read %d/%d DC partitions\n", + dc_resp->partitions_returned, dc_resp->avail_partition_count); + return dc_resp->partitions_returned; +} + +/** + * cxl_dev_dc_identify() - Reads the dynamic capacity information from the + * device. + * @mbox: Mailbox to query + * @dc_info: The dynamic partition information to return + * + * Read Dynamic Capacity information from the device and return the partition + * information. + * + * Return: 0 if identify was executed successfully, -ERRNO on error. + * on error only dc_info is left unchanged. + */ +int cxl_dev_dc_identify(struct cxl_mailbox *mbox, + struct cxl_dc_partition_info *dc_info) +{ + struct cxl_dc_partition_info partitions[CXL_MAX_DC_PARTITIONS]; + struct cxl_mbox_get_dc_config_out *dc_resp __free(kfree) = NULL; + struct device *dev = mbox->host; + u8 start_partition; + u8 num_partitions; + u8 partition_count; + size_t dc_resp_size; + + /* Bound requested number of partitions by mailbox payload size */ + partition_count = min_t(size_t, CXL_MAX_DC_PARTITIONS, + (mbox->payload_size - sizeof(*dc_resp) - + sizeof(struct cxl_mbox_get_dc_config_tail)) / + sizeof(struct cxl_dc_partition)); + dc_resp_size = struct_size(dc_resp, partition, partition_count) + + sizeof(struct cxl_mbox_get_dc_config_tail); + + dc_resp = kmalloc(dc_resp_size, GFP_KERNEL); + if (!dc_resp) + return -ENOMEM; + + /* + * Read and check all partition information for validity and potential + * debugging; see debug output in cxl_dc_check() + */ + start_partition = 0; + num_partitions = 0; + do { + int rc, i, j; + + rc = cxl_get_dc_config(mbox, start_partition, partition_count, + dc_resp, dc_resp_size); + if (rc < 0) { + dev_err(dev, "Failed to get DC config: %d\n", rc); + return rc; + } + + if (rc == 0) { + dev_err(dev, + "Device reported %u partitions available but returned none at index %u\n", + dc_resp->avail_partition_count, start_partition); + return -EIO; + } + + num_partitions += rc; + + if (num_partitions < 1 || num_partitions > CXL_MAX_DC_PARTITIONS) { + dev_err(dev, "Invalid num of dynamic capacity partitions %d\n", + num_partitions); + return -EINVAL; + } + + for (i = start_partition, j = 0; i < num_partitions; i++, j++) { + rc = cxl_dc_check(dev, partitions, i, + &dc_resp->partition[j]); + if (rc) + return rc; + } + + start_partition = num_partitions; + + } while (num_partitions < dc_resp->avail_partition_count); + + /* Return 1st partition */ + dc_info->start = partitions[0].start; + dc_info->size = partitions[0].size; + dev_dbg(dev, "Returning partition 0 %llu size %llu\n", + dc_info->start, dc_info->size); + + return 0; +} +EXPORT_SYMBOL_NS_GPL(cxl_dev_dc_identify, "CXL"); + static void add_part(struct cxl_dpa_info *info, u64 start, u64 size, enum cxl_partition_mode mode) { int i = info->nr_partitions; @@ -1422,6 +1613,35 @@ int cxl_get_dirty_count(struct cxl_memdev_state *mds, u32 *count) } EXPORT_SYMBOL_NS_GPL(cxl_get_dirty_count, "CXL"); +void cxl_configure_dcd(struct cxl_memdev_state *mds, struct cxl_dpa_info *info) +{ + struct cxl_dc_partition_info dc_info = { 0 }; + struct device *dev = mds->cxlds.dev; + int rc; + + rc = cxl_dev_dc_identify(&mds->cxlds.cxl_mbox, &dc_info); + if (rc) { + dev_warn(dev, + "Failed to read Dynamic Capacity config: %d\n", rc); + cxl_disable_dcd(mds); + return; + } + + /* Skips between pmem and the dynamic partition are not supported */ + if (dc_info.start != info->size) { + dev_warn(dev, + "Dynamic Capacity skip from pmem not supported\n"); + cxl_disable_dcd(mds); + return; + } + + info->size += dc_info.size; + dev_dbg(dev, "Adding dynamic ram partition 1; %llu size %llu\n", + dc_info.start, dc_info.size); + add_part(info, dc_info.start, dc_info.size, CXL_PARTMODE_DYNAMIC_RAM_1); +} +EXPORT_SYMBOL_NS_GPL(cxl_configure_dcd, "CXL"); + int cxl_arm_dirty_shutdown(struct cxl_memdev_state *mds) { struct cxl_mailbox *cxl_mbox = &mds->cxlds.cxl_mbox; diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index 616eeaeee5b9..a9782939d82b 100644 --- a/drivers/cxl/cxlmem.h +++ b/drivers/cxl/cxlmem.h @@ -407,6 +407,8 @@ struct cxl_security_state { struct kernfs_node *sanitize_node; }; +#define CXL_MAX_DC_PARTITIONS 8 + static inline resource_size_t cxl_pmem_size(struct cxl_dev_state *cxlds) { /* @@ -691,6 +693,39 @@ struct cxl_mbox_set_shutdown_state_in { u8 state; } __packed; +/* See CXL r4.0 Table 8-178 get dynamic capacity config Input Payload */ +struct cxl_mbox_get_dc_config_in { + u8 partition_count; + u8 start_partition_index; +} __packed; + +/* See CXL r4.0 Table 8-179 get dynamic capacity config Output Payload */ +struct cxl_mbox_get_dc_config_out { + u8 avail_partition_count; + u8 partitions_returned; + u8 rsvd[6]; + /* See CXL r4.0 Table 8-180 */ + struct cxl_dc_partition { + __le64 base; + __le64 decode_length; + __le64 length; + __le64 block_size; + __le32 dsmad_handle; + u8 flags; + u8 rsvd[3]; + } __packed partition[] __counted_by(partitions_returned); + /* Trailing extent/tag count fields unused */ +} __packed; + +/* Trailing counts; cannot be a member after the flex array above */ +struct cxl_mbox_get_dc_config_tail { + __le32 num_extents_supported; + __le32 num_extents_available; + __le32 num_tags_supported; + __le32 num_tags_available; +} __packed; +#define CXL_DCD_BLOCK_LINE_SIZE 0x40 + /* Set Timestamp CXL 3.0 Spec 8.2.9.4.2 */ struct cxl_mbox_set_timestamp_in { __le64 timestamp; @@ -814,9 +849,18 @@ enum { int cxl_internal_send_cmd(struct cxl_mailbox *cxl_mbox, struct cxl_mbox_cmd *cmd); int cxl_dev_state_identify(struct cxl_memdev_state *mds); + +struct cxl_dc_partition_info { + u64 start; + u64 size; +}; + +int cxl_dev_dc_identify(struct cxl_mailbox *mbox, + struct cxl_dc_partition_info *dc_info); int cxl_await_media_ready(struct cxl_dev_state *cxlds); int cxl_enumerate_cmds(struct cxl_memdev_state *mds); int cxl_mem_dpa_fetch(struct cxl_memdev_state *mds, struct cxl_dpa_info *info); +void cxl_configure_dcd(struct cxl_memdev_state *mds, struct cxl_dpa_info *info); struct cxl_memdev_state *cxl_memdev_state_create(struct device *dev, u64 serial, u16 dvsec); void set_exclusive_cxl_commands(struct cxl_memdev_state *mds, @@ -830,6 +874,17 @@ void cxl_event_trace_record(struct cxl_memdev *cxlmd, const uuid_t *uuid, union cxl_event *evt); int cxl_get_dirty_count(struct cxl_memdev_state *mds, u32 *count); int cxl_arm_dirty_shutdown(struct cxl_memdev_state *mds); + +static inline bool cxl_dcd_supported(struct cxl_memdev_state *mds) +{ + return mds->dcd_supported; +} + +static inline void cxl_disable_dcd(struct cxl_memdev_state *mds) +{ + mds->dcd_supported = false; +} + int cxl_set_timestamp(struct cxl_memdev_state *mds); int cxl_poison_state_init(struct cxl_memdev_state *mds); int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len, diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c index 267c679b0b3c..9b320a2b6fe0 100644 --- a/drivers/cxl/pci.c +++ b/drivers/cxl/pci.c @@ -870,6 +870,9 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) if (rc) return rc; + if (cxl_dcd_supported(mds)) + cxl_configure_dcd(mds, &range_info); + rc = cxl_dpa_setup(cxlds, &range_info); if (rc) return rc; diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h index 016c74fb747c..87c2bd73df21 100644 --- a/include/cxl/cxl.h +++ b/include/cxl/cxl.h @@ -133,6 +133,7 @@ struct cxl_dpa_perf { enum cxl_partition_mode { CXL_PARTMODE_RAM, CXL_PARTMODE_PMEM, + CXL_PARTMODE_DYNAMIC_RAM_1, }; /** @@ -147,7 +148,7 @@ struct cxl_dpa_partition { enum cxl_partition_mode mode; }; -#define CXL_NR_PARTITIONS_MAX 2 +#define CXL_NR_PARTITIONS_MAX 3 /** * struct cxl_dev_state - The driver device state -- 2.43.0