[PATCH v6 0/6] CXL Poison List Retrieval & Tracing

[PATCH v6 0/6] CXL Poison List Retrieval & Tracing

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

This is not targeting the 6.3 merge window.

Changes in v6:
- Remove the ABI that collected poison per region, and added the
  region info to the per memdev collection.  (Dan)
  This means Patch 4 is brand new:
  	cxl/region: Provide region info to the cxl_poison trace event

- Also added Patch 5: cxl/trace: Add an HPA to cxl_poison trace events
  to this set. It comes w a couple of Review Tags, and is unchanged,
  from a v2 last posted upstream.
- Dropped Jonathan's Review on Patch 3 because of changes
- Remove local var 'cxlps' (cxl_poison_state) (Dan)
- Trigger sysfs attr on boolean truisms only (Dan)
- Remove unneeded param pcidev from trace call. 
- Mock: add __packed, and le64_to_cpu(() (Dan)
- Abbreviate less: s/max_mer/max_errors (Dan)
- Rename trace field 'pcidev', 'host' (Dan)
- getpoison_po/payload_out (Dan)
- Add serial no. to trace (Dan)
- s/getpoison_lock/lock (Dan)
- s/tmp/trigger

Link to v5: https://lore.kernel.org/linux-cxl/cover.1674070170.git.alison.schofield@intel.com/

Add support for retrieving device poison lists and store the returned
error records as kernel trace events.

The handling of the poison list is guided by the CXL 3.0 Specification
Section 8.2.9.8.4.1. [1] 

Example:
$ echo 1 > /sys/bus/cxl/devices/mem0/trigger_poison_list
cxl_poison: memdev=mem0 serial=0 host=cxl_mem.0 region=region4 region_uuid=117b2cf4-b160-4090-9361-ba31b9649317 hpa=0xf0d0000000 dpa=0x40000000 length=0x40 source=Internal flags= overflow_time=0

[1]: https://www.computeexpresslink.org/download-the-specification

Alison Schofield (6):
  cxl/mbox: Add GET_POISON_LIST mailbox command
  cxl/trace: Add TRACE support for CXL media-error records
  cxl/memdev: Add trigger_poison_list sysfs attribute
  cxl/region: Provide region info to the cxl_poison trace event
  cxl/trace: Add an HPA to cxl_poison trace events
  tools/testing/cxl: Mock support for Get Poison List

 Documentation/ABI/testing/sysfs-bus-cxl | 14 ++++
 drivers/cxl/core/core.h                 |  5 ++
 drivers/cxl/core/mbox.c                 | 74 +++++++++++++++++++
 drivers/cxl/core/memdev.c               | 68 ++++++++++++++++++
 drivers/cxl/core/region.c               | 82 +++++++++++++++++++++
 drivers/cxl/core/trace.c                | 94 +++++++++++++++++++++++++
 drivers/cxl/core/trace.h                | 92 ++++++++++++++++++++++++
 drivers/cxl/cxlmem.h                    | 69 +++++++++++++++++-
 drivers/cxl/pci.c                       |  4 ++
 tools/testing/cxl/test/mem.c            | 42 +++++++++++
 10 files changed, 543 insertions(+), 1 deletion(-)


base-commit: dbe9f7d1e155b97a42f7da81e22acc98fe0a9072
-- 
2.37.3

[PATCH v6 1/6] cxl/mbox: Add GET_POISON_LIST mailbox command

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

CXL devices maintain a list of locations that are poisoned or result
in poison if the addresses are accessed by the host.

Per the spec (CXL 3.0 8.2.9.8.4.1), the device returns this Poison
list as a set of  Media Error Records that include the source of the
error, the starting device physical address and length. The length is
the number of adjacent DPAs in the record and is in units of 64 bytes.

Retrieve the poison list.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 drivers/cxl/core/mbox.c | 72 +++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/cxlmem.h    | 67 ++++++++++++++++++++++++++++++++++++++
 drivers/cxl/pci.c       |  4 +++
 3 files changed, 143 insertions(+)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 03909b6cef55..a57de8896846 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -5,6 +5,8 @@
 #include <linux/debugfs.h>
 #include <linux/ktime.h>
 #include <linux/mutex.h>
+#include <asm/unaligned.h>
+#include <cxlpci.h>
 #include <cxlmem.h>
 #include <cxl.h>
 
@@ -989,6 +991,7 @@ int cxl_dev_state_identify(struct cxl_dev_state *cxlds)
 	/* See CXL 2.0 Table 175 Identify Memory Device Output Payload */
 	struct cxl_mbox_identify id;
 	struct cxl_mbox_cmd mbox_cmd;
+	u32 val;
 	int rc;
 
 	mbox_cmd = (struct cxl_mbox_cmd) {
@@ -1012,6 +1015,11 @@ int cxl_dev_state_identify(struct cxl_dev_state *cxlds)
 	cxlds->lsa_size = le32_to_cpu(id.lsa_size);
 	memcpy(cxlds->firmware_version, id.fw_revision, sizeof(id.fw_revision));
 
+	if (test_bit(CXL_MEM_COMMAND_ID_GET_POISON, cxlds->enabled_cmds)) {
+		val = get_unaligned_le24(id.poison_list_max_mer);
+		cxlds->poison.max_errors = min_t(u32, val, CXL_POISON_LIST_MAX);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_dev_state_identify, CXL);
@@ -1102,6 +1110,70 @@ int cxl_set_timestamp(struct cxl_dev_state *cxlds)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_set_timestamp, CXL);
 
+int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
+		       struct cxl_region *cxlr)
+{
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_mbox_poison_payload_out *po;
+	struct cxl_mbox_poison_payload_in pi;
+	struct cxl_mbox_cmd mbox_cmd;
+	int nr_records = 0;
+	int rc;
+
+	rc = mutex_lock_interruptible(&cxlds->poison.lock);
+	if (rc)
+		return rc;
+
+	po = cxlds->poison.payload_out;
+	pi.offset = cpu_to_le64(offset);
+	pi.length = cpu_to_le64(len / CXL_POISON_LEN_MULT);
+
+	mbox_cmd = (struct cxl_mbox_cmd) {
+		.opcode = CXL_MBOX_OP_GET_POISON,
+		.size_in = sizeof(pi),
+		.payload_in = &pi,
+		.size_out = cxlds->payload_size,
+		.payload_out = po,
+		.min_out = struct_size(po, record, 0),
+	};
+
+	do {
+		rc = cxl_internal_send_cmd(cxlds, &mbox_cmd);
+		if (rc)
+			break;
+
+		/* TODO TRACE the media error records */
+
+		/* Protect against an uncleared _FLAG_MORE */
+		nr_records = nr_records + le16_to_cpu(po->count);
+		if (nr_records >= cxlds->poison.max_errors) {
+			dev_dbg(&cxlmd->dev, "Max Error Records reached: %d\n",
+				nr_records);
+			break;
+		}
+	} while (po->flags & CXL_POISON_FLAG_MORE);
+
+	mutex_unlock(&cxlds->poison.lock);
+	return rc;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_mem_get_poison, CXL);
+
+int cxl_poison_state_init(struct cxl_dev_state *cxlds)
+{
+	if (!test_bit(CXL_MEM_COMMAND_ID_GET_POISON, cxlds->enabled_cmds))
+		return 0;
+
+	cxlds->poison.payload_out = devm_kzalloc(cxlds->dev,
+						 cxlds->payload_size,
+						 GFP_KERNEL);
+	if (!cxlds->poison.payload_out)
+		return -ENOMEM;
+
+	mutex_init(&cxlds->poison.lock);
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_poison_state_init, CXL);
+
 struct cxl_dev_state *cxl_dev_state_create(struct device *dev)
 {
 	struct cxl_dev_state *cxlds;
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 802b5b396daf..17ea575f8a06 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -222,6 +222,24 @@ struct cxl_event_state {
 	struct mutex log_lock;
 };
 
+/**
+ * struct cxl_poison_state - Poison list retrieval
+ *
+ * @max_errors: Maximum media error records held in device cache
+ * @payload_out: The poison list payload returned by device
+ * @lock: Protect reads of the poison list
+ *
+ * Reads of the poison list are synchronized to ensure that a reader
+ * does not get an incomplete list because their request overlapped
+ * (was interrupted or preceded by) another read request of the same
+ * DPA range. CXL Spec 3.0 Section 8.2.9.8.4.1
+ */
+struct cxl_poison_state {
+	u32 max_errors;
+	struct cxl_mbox_poison_payload_out *payload_out;
+	struct mutex lock;  /* Protect reads of poison list */
+};
+
 /**
  * struct cxl_dev_state - The driver device state
  *
@@ -257,6 +275,7 @@ struct cxl_event_state {
  * @info: Cached DVSEC information about the device.
  * @serial: PCIe Device Serial Number
  * @doe_mbs: PCI DOE mailbox array
+ * @poison: poison list retrieval info
  * @mbox_send: @dev specific transport for transmitting mailbox commands
  *
  * See section 8.2.9.5.2 Capacity Configuration and Label Storage for
@@ -296,6 +315,7 @@ struct cxl_dev_state {
 	struct xarray doe_mbs;
 
 	struct cxl_event_state event;
+	struct cxl_poison_state poison;
 
 	int (*mbox_send)(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd);
 };
@@ -544,6 +564,50 @@ struct cxl_mbox_set_timestamp_in {
 
 } __packed;
 
+/* Get Poison List  CXL 3.0 Spec 8.2.9.8.4.1 */
+struct cxl_mbox_poison_payload_in {
+	__le64 offset;
+	__le64 length;
+} __packed;
+
+struct cxl_mbox_poison_payload_out {
+	u8 flags;
+	u8 rsvd1;
+	__le64 overflow_t;
+	__le16 count;
+	u8 rsvd2[20];
+	struct cxl_poison_record {
+		__le64 address;
+		__le32 length;
+		__le32 rsvd;
+	} __packed record[];
+} __packed;
+
+/*
+ * Get Poison List address field encodes the starting
+ * address of poison, and the source of the poison.
+ */
+#define CXL_POISON_START_MASK		GENMASK_ULL(63, 6)
+#define CXL_POISON_SOURCE_MASK		GENMASK(2, 0)
+
+/* Get Poison List record length is in units of 64 bytes */
+#define CXL_POISON_LEN_MULT	64
+
+/* Kernel defined maximum for a list of poison errors */
+#define CXL_POISON_LIST_MAX	1024
+
+/* Get Poison List: Payload out flags */
+#define CXL_POISON_FLAG_MORE            BIT(0)
+#define CXL_POISON_FLAG_OVERFLOW        BIT(1)
+#define CXL_POISON_FLAG_SCANNING        BIT(2)
+
+/* Get Poison List: Poison Source */
+#define CXL_POISON_SOURCE_UNKNOWN	0
+#define CXL_POISON_SOURCE_EXTERNAL	1
+#define CXL_POISON_SOURCE_INTERNAL	2
+#define CXL_POISON_SOURCE_INJECTED	3
+#define CXL_POISON_SOURCE_VENDOR	7
+
 /**
  * struct cxl_mem_command - Driver representation of a memory device command
  * @info: Command information as it exists for the UAPI
@@ -615,6 +679,9 @@ void set_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds
 void clear_exclusive_cxl_commands(struct cxl_dev_state *cxlds, unsigned long *cmds);
 void cxl_mem_get_event_records(struct cxl_dev_state *cxlds, u32 status);
 int cxl_set_timestamp(struct cxl_dev_state *cxlds);
+int cxl_poison_state_init(struct cxl_dev_state *cxlds);
+int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
+		       struct cxl_region *cxlr);
 
 #ifdef CONFIG_CXL_SUSPEND
 void cxl_mem_active_inc(void);
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 4cf9a2191602..7ca06016dac9 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -713,6 +713,10 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		return rc;
 
+	rc = cxl_poison_state_init(cxlds);
+	if (rc)
+		return rc;
+
 	rc = cxl_dev_state_identify(cxlds);
 	if (rc)
 		return rc;
-- 
2.37.3

[PATCH v6 2/6] cxl/trace: Add TRACE support for CXL media-error records

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

CXL devices may support the retrieval of a device poison list.
Add a new trace event that the CXL subsystem may use to log
the media-error records returned in the poison list.

Log each media-error record as a trace event of type 'cxl_poison'.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 drivers/cxl/core/mbox.c  |  4 +-
 drivers/cxl/core/trace.h | 85 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index a57de8896846..131ee336b69e 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -1142,7 +1142,9 @@ int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
 		if (rc)
 			break;
 
-		/* TODO TRACE the media error records */
+		for (int i = 0; i < le16_to_cpu(po->count); i++)
+			trace_cxl_poison(cxlmd, cxlr, &po->record[i],
+					 po->flags, po->overflow_t);
 
 		/* Protect against an uncleared _FLAG_MORE */
 		nr_records = nr_records + le16_to_cpu(po->count);
diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
index c72ef9321cfe..c493955719ce 100644
--- a/drivers/cxl/core/trace.h
+++ b/drivers/cxl/core/trace.h
@@ -7,6 +7,7 @@
 #define _CXL_EVENTS_H
 
 #include <linux/tracepoint.h>
+#include <linux/pci.h>
 #include <asm-generic/unaligned.h>
 
 #include <cxl.h>
@@ -581,6 +582,90 @@ TRACE_EVENT(cxl_memory_module,
 	)
 );
 
+#define __show_poison_source(source)                          \
+	__print_symbolic(source,                              \
+		{ CXL_POISON_SOURCE_UNKNOWN,   "Unknown"  },  \
+		{ CXL_POISON_SOURCE_EXTERNAL,  "External" },  \
+		{ CXL_POISON_SOURCE_INTERNAL,  "Internal" },  \
+		{ CXL_POISON_SOURCE_INJECTED,  "Injected" },  \
+		{ CXL_POISON_SOURCE_VENDOR,    "Vendor"   })
+
+#define show_poison_source(source)			     \
+	(((source > CXL_POISON_SOURCE_INJECTED) &&	     \
+	 (source != CXL_POISON_SOURCE_VENDOR)) ? "Reserved"  \
+	 : __show_poison_source(source))
+
+#define show_poison_flags(flags)                             \
+	__print_flags(flags, "|",                            \
+		{ CXL_POISON_FLAG_MORE,      "More"     },   \
+		{ CXL_POISON_FLAG_OVERFLOW,  "Overflow"  },  \
+		{ CXL_POISON_FLAG_SCANNING,  "Scanning"  })
+
+#define __cxl_poison_addr(record)					\
+	(le64_to_cpu(record->address))
+#define cxl_poison_record_dpa(record)					\
+	(__cxl_poison_addr(record) & CXL_POISON_START_MASK)
+#define cxl_poison_record_source(record)				\
+	(__cxl_poison_addr(record)  & CXL_POISON_SOURCE_MASK)
+#define cxl_poison_record_length(record)				\
+	(le32_to_cpu(record->length) * CXL_POISON_LEN_MULT)
+#define cxl_poison_overflow(flags, time)				\
+	(flags & CXL_POISON_FLAG_OVERFLOW ? le64_to_cpu(time) : 0)
+#define cxl_poison_host_name(cxlmd)					\
+	(dev_name(cxlmd->dev.parent))
+
+TRACE_EVENT(cxl_poison,
+
+	    TP_PROTO(struct cxl_memdev *cxlmd, struct cxl_region *region,
+		     const struct cxl_poison_record *record,
+		     u8 flags, __le64 overflow_t),
+
+	    TP_ARGS(cxlmd, region, record, flags, overflow_t),
+
+	    TP_STRUCT__entry(
+		__string(memdev, dev_name(&cxlmd->dev))
+		__string(host, cxl_poison_host_name(cxlmd))
+		__field(u64, serial)
+		__string(region, region)
+		__field(u64, overflow_t)
+		__field(u64, dpa)
+		__field(u32, length)
+		__array(char, uuid, 16)
+		__field(u8, source)
+		__field(u8, flags)
+	    ),
+
+	    TP_fast_assign(
+		__assign_str(memdev, dev_name(&cxlmd->dev));
+		__assign_str(host, cxl_poison_host_name(cxlmd));
+		__entry->serial = cxlmd->cxlds->serial;
+		__entry->overflow_t = cxl_poison_overflow(flags, overflow_t);
+		__entry->dpa = cxl_poison_record_dpa(record);
+		__entry->length = cxl_poison_record_length(record);
+		__entry->source = cxl_poison_record_source(record);
+		__entry->flags = flags;
+		if (region) {
+			__assign_str(region, dev_name(&region->dev));
+			memcpy(__entry->uuid, &region->params.uuid, 16);
+		} else {
+			__assign_str(region, "");
+			memset(__entry->uuid, 0, 16);
+		}
+	    ),
+
+	    TP_printk("memdev=%s serial=%llu host=%s region=%s region_uuid=%pU dpa=0x%llx length=0x%x source=%s flags=%s overflow_time=%llu",
+		__get_str(memdev),
+		__entry->serial,
+		__get_str(host),
+		__get_str(region),
+		__entry->uuid,
+		__entry->dpa,
+		__entry->length,
+		show_poison_source(__entry->source),
+		show_poison_flags(__entry->flags),
+		__entry->overflow_t)
+);
+
 #endif /* _CXL_EVENTS_H */
 
 #define TRACE_INCLUDE_FILE trace
-- 
2.37.3

[PATCH v6 3/6] cxl/memdev: Add trigger_poison_list sysfs attribute

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

When a boolean 'true' is written to this attribute the memdev driver
retrieves the poison list from the device. The list consists of
addresses that are poisoned, or would result in poison if accessed,
and the source of the poison. This attribute is only visible for
devices supporting the capability. The retrieved errors are logged
as kernel trace events with the label 'cxl_poison'.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 Documentation/ABI/testing/sysfs-bus-cxl | 14 +++++++
 drivers/cxl/core/memdev.c               | 56 +++++++++++++++++++++++++
 drivers/cxl/cxlmem.h                    |  2 +-
 3 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 329a7e46c805..035213f47882 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -403,3 +403,17 @@ Description:
 		1), and checks that the hardware accepts the commit request.
 		Reading this value indicates whether the region is committed or
 		not.
+
+
+What:		/sys/bus/cxl/devices/memX/trigger_poison_list
+Date:		November, 2022
+KernelVersion:	v6.2
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) When a boolean 'true' is written to this attribute the
+		memdev driver retrieves the poison list from the device. The
+		list consists of addresses that are poisoned, or would result
+		in poison if accessed, and the source of the poison. This
+		attribute is only visible for devices supporting the
+		capability. The retrieved errors are logged as kernel
+		trace events with the label 'cxl_poison'.
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index a74a93310d26..19b833c9cf35 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -106,12 +106,60 @@ static ssize_t numa_node_show(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RO(numa_node);
 
+static int cxl_get_poison_by_memdev(struct cxl_memdev *cxlmd)
+{
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	u64 offset, length;
+	int rc = 0;
+
+	/* CXL 3.0 Spec 8.2.9.8.4.1 Separate pmem and ram poison requests */
+	if (resource_size(&cxlds->pmem_res)) {
+		offset = cxlds->pmem_res.start;
+		length = resource_size(&cxlds->pmem_res);
+		rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
+		if (rc)
+			return rc;
+	}
+	if (resource_size(&cxlds->ram_res)) {
+		offset = cxlds->ram_res.start;
+		length = resource_size(&cxlds->ram_res);
+		rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
+		/*
+		 * Invalid Physical Address is not an error for
+		 * volatile addresses. Device support is optional.
+		 */
+		if (rc == -EFAULT)
+			rc = 0;
+	}
+	return rc;
+}
+
+static ssize_t trigger_poison_list_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+	bool trigger;
+	int rc;
+
+	if (kstrtobool(buf, &trigger) || !trigger)
+		return -EINVAL;
+
+	down_read(&cxl_dpa_rwsem);
+	rc = cxl_get_poison_by_memdev(cxlmd);
+	up_read(&cxl_dpa_rwsem);
+
+	return rc ? rc : len;
+}
+static DEVICE_ATTR_WO(trigger_poison_list);
+
 static struct attribute *cxl_memdev_attributes[] = {
 	&dev_attr_serial.attr,
 	&dev_attr_firmware_version.attr,
 	&dev_attr_payload_max.attr,
 	&dev_attr_label_storage_size.attr,
 	&dev_attr_numa_node.attr,
+	&dev_attr_trigger_poison_list.attr,
 	NULL,
 };
 
@@ -130,6 +178,14 @@ static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
 {
 	if (!IS_ENABLED(CONFIG_NUMA) && a == &dev_attr_numa_node.attr)
 		return 0;
+
+	if (a == &dev_attr_trigger_poison_list.attr) {
+		struct device *dev = kobj_to_dev(kobj);
+
+		if (!test_bit(CXL_MEM_COMMAND_ID_GET_POISON,
+			      to_cxl_memdev(dev)->cxlds->enabled_cmds))
+			return 0;
+	}
 	return a->mode;
 }
 
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 17ea575f8a06..7c2489dd344c 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -140,7 +140,7 @@ struct cxl_mbox_cmd {
 	C(FWROLLBACK, -ENXIO, "rolled back to the previous active FW"),         \
 	C(FWRESET, -ENXIO, "FW failed to activate, needs cold reset"),		\
 	C(HANDLE, -ENXIO, "one or more Event Record Handles were invalid"),     \
-	C(PADDR, -ENXIO, "physical address specified is invalid"),		\
+	C(PADDR, -EFAULT, "physical address specified is invalid"),		\
 	C(POISONLMT, -ENXIO, "poison injection limit has been reached"),        \
 	C(MEDIAFAILURE, -ENXIO, "permanent issue with the media"),		\
 	C(ABORT, -ENXIO, "background cmd was aborted by device"),               \
-- 
2.37.3

[PATCH v6 4/6] cxl/region: Provide region info to the cxl_poison trace event

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

User space may need to know which region, if any, maps the poison
address(es) logged in a cxl_poison trace event. Since the mapping
of DPAs (device physical addresses) to a region can change, the
kernel must provide this information at the time the poison list
is read. The event informs user space that at event <timestamp>
this <region> mapped to this <DPA>, which is poisoned.

The cxl_poison trace event is already wired up to log the region
name and uuid if it receives param 'struct cxl_region'.

In order to provide that cxl_region, add another method for gathering
poison - by committed endpoint decoder mappings. This method is only
available with CONFIG_CXL_REGION and is only used if a region actually
maps the memdev where poison is being read. The default method remains:
read the poison by memdev resource.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 drivers/cxl/core/core.h   |  5 +++
 drivers/cxl/core/memdev.c | 14 ++++++-
 drivers/cxl/core/region.c | 82 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 8c04672dca56..2f9bd8651eb1 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -22,7 +22,12 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled);
 #define CXL_PMEM_REGION_TYPE(x) (&cxl_pmem_region_type)
 int cxl_region_init(void);
 void cxl_region_exit(void);
+int cxl_get_poison_by_endpoint(struct device *dev, void *data);
 #else
+static inline int cxl_get_poison_by_endpoint(struct device *dev, void *data)
+{
+	return 0;
+}
 static inline void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
 {
 }
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 19b833c9cf35..8696d7b508b6 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -139,14 +139,26 @@ static ssize_t trigger_poison_list_store(struct device *dev,
 					 const char *buf, size_t len)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+	struct cxl_port *port;
 	bool trigger;
 	int rc;
 
 	if (kstrtobool(buf, &trigger) || !trigger)
 		return -EINVAL;
 
+	port = dev_get_drvdata(&cxlmd->dev);
+	if (!port || !is_cxl_endpoint(port))
+		return -EINVAL;
+
 	down_read(&cxl_dpa_rwsem);
-	rc = cxl_get_poison_by_memdev(cxlmd);
+	if (port->commit_end == -1)
+		/* No regions mapped to this memdev */
+		rc = cxl_get_poison_by_memdev(cxlmd);
+	else
+		/* Regions mapped, collect poison by endpoint */
+		rc = device_for_each_child(&port->dev, port,
+					   cxl_get_poison_by_endpoint);
+
 	up_read(&cxl_dpa_rwsem);
 
 	return rc ? rc : len;
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 67e83d961670..0ac08e9106af 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1826,6 +1826,88 @@ struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
 }
 EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, CXL);
 
+int cxl_get_poison_by_endpoint(struct device *dev, void *data)
+{
+	struct cxl_endpoint_decoder *cxled;
+	struct cxl_port *port = data;
+	struct cxl_dev_state *cxlds;
+	struct cxl_memdev *cxlmd;
+	u64 offset, length;
+	int rc = 0;
+
+	down_read(&cxl_dpa_rwsem);
+
+	if (!is_endpoint_decoder(dev))
+		goto out;
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	if (!cxled->dpa_res || !resource_size(cxled->dpa_res))
+		goto out;
+
+	/*
+	 * Get the poison by decoder for mapped resources. This
+	 * separates pmem and ram poison list reads, as the spec
+	 * requires, and provides the region for the trace event.
+	 */
+	cxlmd = cxled_to_memdev(cxled);
+	length = cxled->dpa_res->end - cxled->dpa_res->start + 1;
+	rc = cxl_mem_get_poison(cxlmd, cxled->dpa_res->start, length,
+				cxled->cxld.region);
+	if (rc == -EFAULT && cxled->mode == CXL_DECODER_RAM)
+		rc = 0;
+	if (rc)
+		goto out;
+
+	/* Get poison in a skip range */
+	if (cxled->skip) {
+		rc = cxl_mem_get_poison(cxlmd, 0, cxled->skip, NULL);
+		if (rc == -EFAULT && cxled->mode == CXL_DECODER_RAM)
+			rc = 0;
+		if (rc)
+			goto out;
+	}
+
+	/* Iterate until commit_end is reached */
+	if (cxled->cxld.id < port->commit_end)
+		goto out;
+
+	/*
+	 * Reach here with the last committed decoder only.
+	 * Knowing that PMEM must always follow RAM, get poison
+	 * for unmapped ranges based on the last decoder's mode:
+	 *	ram: scan remains of ram range, then scan for pmem
+	 *	pmem: scan remains of pmem range
+	 */
+	cxlds = cxlmd->cxlds;
+
+	if (cxled->mode == CXL_DECODER_RAM) {
+		offset = cxled->dpa_res->end + 1;
+		length = resource_size(&cxlds->ram_res) - offset;
+		rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
+		if (rc == -EFAULT)
+			rc = 0;
+		if (rc)
+			goto out;
+	}
+	if (cxled->mode == CXL_DECODER_PMEM) {
+		offset = cxled->dpa_res->end + 1;
+		length = resource_size(&cxlds->pmem_res) - offset;
+	} else if (resource_size(&cxlds->pmem_res)) {
+		offset = cxlds->pmem_res.start;
+		length = resource_size(&cxlds->pmem_res);
+	} else {
+		rc = 1;
+		goto out;
+	}
+	/* Final get poison call. Return rc or 1 to stop iteration. */
+	rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
+	if (!rc)
+		rc = 1;
+out:
+	up_read(&cxl_dpa_rwsem);
+	return rc;
+}
+
 static struct lock_class_key cxl_pmem_region_key;
 
 static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
-- 
2.37.3

[PATCH v6 5/6] cxl/trace: Add an HPA to cxl_poison trace events

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

When a cxl_poison trace event is reported for a region, the poisoned
Device Physical Address (DPA) can be translated to a Host Physical
Address (HPA) for consumption by user space.

Translate and add the resulting HPA to the cxl_poison trace event.
Follow the device decode logic as defined in the CXL Spec 3.0 Section
8.2.4.19.13.

If no region currently maps the poison, assign ULLONG_MAX to the
cxl_poison hpa event field.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 drivers/cxl/core/trace.c | 94 ++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/core/trace.h |  9 +++-
 2 files changed, 102 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/trace.c b/drivers/cxl/core/trace.c
index 29ae7ce81dc5..d0403dc3c8ab 100644
--- a/drivers/cxl/core/trace.c
+++ b/drivers/cxl/core/trace.c
@@ -1,5 +1,99 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /* Copyright(c) 2022 Intel Corporation. All rights reserved. */
 
+#include <cxl.h>
+#include "core.h"
+
 #define CREATE_TRACE_POINTS
 #include "trace.h"
+
+static bool cxl_is_hpa_in_range(u64 hpa, struct cxl_region *cxlr, int pos)
+{
+	struct cxl_region_params *p = &cxlr->params;
+	int gran = p->interleave_granularity;
+	int ways = p->interleave_ways;
+	u64 offset;
+
+	/* Is the hpa within this region at all */
+	if (hpa < p->res->start || hpa > p->res->end) {
+		dev_dbg(&cxlr->dev,
+			"Addr trans fail: hpa 0x%llx not in region\n", hpa);
+		return false;
+	}
+
+	/* Is the hpa in an expected chunk for its pos(-ition) */
+	offset = hpa - p->res->start;
+	offset = do_div(offset, gran * ways);
+	if ((offset >= pos * gran) && (offset < (pos + 1) * gran))
+		return true;
+
+	dev_dbg(&cxlr->dev,
+		"Addr trans fail: hpa 0x%llx not in expected chunk\n", hpa);
+
+	return false;
+}
+
+static u64 cxl_dpa_to_hpa(u64 dpa,  struct cxl_region *cxlr,
+			  struct cxl_endpoint_decoder *cxled)
+{
+	u64 dpa_offset, hpa_offset, bits_upper, mask_upper, hpa;
+	struct cxl_region_params *p = &cxlr->params;
+	int pos = cxled->pos;
+	u16 eig = 0;
+	u8 eiw = 0;
+
+	ways_to_eiw(p->interleave_ways, &eiw);
+	granularity_to_eig(p->interleave_granularity, &eig);
+
+	/*
+	 * The device position in the region interleave set was removed
+	 * from the offset at HPA->DPA translation. To reconstruct the
+	 * HPA, place the 'pos' in the offset.
+	 *
+	 * The placement of 'pos' in the HPA is determined by interleave
+	 * ways and granularity and is defined in the CXL Spec 3.0 Section
+	 * 8.2.4.19.13 Implementation Note: Device Decode Logic
+	 */
+
+	/* Remove the dpa base */
+	dpa_offset = dpa - cxl_dpa_resource_start(cxled);
+
+	mask_upper = GENMASK_ULL(51, eig + 8);
+
+	if (eiw < 8) {
+		hpa_offset = (dpa_offset & mask_upper) << eiw;
+		hpa_offset |= pos << (eig + 8);
+	} else {
+		bits_upper = (dpa_offset & mask_upper) >> (eig + 8);
+		bits_upper = bits_upper * 3;
+		hpa_offset = ((bits_upper << (eiw - 8)) + pos) << (eig + 8);
+	}
+
+	/* The lower bits remain unchanged */
+	hpa_offset |= dpa_offset & GENMASK_ULL(eig + 7, 0);
+
+	/* Apply the hpa_offset to the region base address */
+	hpa = hpa_offset + p->res->start;
+
+	if (!cxl_is_hpa_in_range(hpa, cxlr, cxled->pos))
+		return ULLONG_MAX;
+
+	return hpa;
+}
+
+u64 cxl_trace_hpa(struct cxl_region *cxlr, struct cxl_memdev *cxlmd,
+		  u64 dpa)
+{
+	struct cxl_region_params *p = &cxlr->params;
+	struct cxl_endpoint_decoder *cxled = NULL;
+
+	for (int i = 0; i <  p->nr_targets; i++) {
+		cxled = p->targets[i];
+		if (cxlmd == cxled_to_memdev(cxled))
+			break;
+	}
+	if (!cxled || cxlmd != cxled_to_memdev(cxled))
+		return ULLONG_MAX;
+
+	return cxl_dpa_to_hpa(dpa, cxlr, cxled);
+}
diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
index c493955719ce..e6114dd0a95c 100644
--- a/drivers/cxl/core/trace.h
+++ b/drivers/cxl/core/trace.h
@@ -614,6 +614,8 @@ TRACE_EVENT(cxl_memory_module,
 #define cxl_poison_host_name(cxlmd)					\
 	(dev_name(cxlmd->dev.parent))
 
+u64 cxl_trace_hpa(struct cxl_region *cxlr, struct cxl_memdev *memdev, u64 dpa);
+
 TRACE_EVENT(cxl_poison,
 
 	    TP_PROTO(struct cxl_memdev *cxlmd, struct cxl_region *region,
@@ -628,6 +630,7 @@ TRACE_EVENT(cxl_poison,
 		__field(u64, serial)
 		__string(region, region)
 		__field(u64, overflow_t)
+		__field(u64, hpa)
 		__field(u64, dpa)
 		__field(u32, length)
 		__array(char, uuid, 16)
@@ -647,18 +650,22 @@ TRACE_EVENT(cxl_poison,
 		if (region) {
 			__assign_str(region, dev_name(&region->dev));
 			memcpy(__entry->uuid, &region->params.uuid, 16);
+			__entry->hpa = cxl_trace_hpa(region, cxlmd,
+						     __entry->dpa);
 		} else {
 			__assign_str(region, "");
 			memset(__entry->uuid, 0, 16);
+			__entry->hpa = ULLONG_MAX;
 		}
 	    ),
 
-	    TP_printk("memdev=%s serial=%llu host=%s region=%s region_uuid=%pU dpa=0x%llx length=0x%x source=%s flags=%s overflow_time=%llu",
+	    TP_printk("memdev=%s serial=%llu host=%s region=%s region_uuid=%pU hpa=0x%llx dpa=0x%llx length=0x%x source=%s flags=%s overflow_time=%llu",
 		__get_str(memdev),
 		__entry->serial,
 		__get_str(host),
 		__get_str(region),
 		__entry->uuid,
+		__entry->hpa,
 		__entry->dpa,
 		__entry->length,
 		show_poison_source(__entry->source),
-- 
2.37.3

[PATCH v6 6/6] tools/testing/cxl: Mock support for Get Poison List

[alison.schofield]

From: Alison Schofield <alison.schofield@intel.com>

Make mock memdevs support the Get Poison List mailbox command.
Return a fake poison error record when the get poison list command
is issued.

This supports testing the kernel tracing and cxl list capabilities
for media errors.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 tools/testing/cxl/test/mem.c | 42 ++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
index 9263b04d35f7..2fa9c18d4c2c 100644
--- a/tools/testing/cxl/test/mem.c
+++ b/tools/testing/cxl/test/mem.c
@@ -7,6 +7,7 @@
 #include <linux/delay.h>
 #include <linux/sizes.h>
 #include <linux/bits.h>
+#include <asm/unaligned.h>
 #include <cxlmem.h>
 
 #include "trace.h"
@@ -40,6 +41,10 @@ static struct cxl_cel_entry mock_cel[] = {
 		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_HEALTH_INFO),
 		.effect = cpu_to_le16(0),
 	},
+	{
+		.opcode = cpu_to_le16(CXL_MBOX_OP_GET_POISON),
+		.effect = cpu_to_le16(0),
+	},
 };
 
 /* See CXL 2.0 Table 181 Get Health Info Output Payload */
@@ -471,6 +476,8 @@ static int mock_id(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd)
 			cpu_to_le64(DEV_SIZE / CXL_CAPACITY_MULTIPLIER),
 	};
 
+	put_unaligned_le24(CXL_POISON_LIST_MAX, id.poison_list_max_mer);
+
 	if (cmd->size_out < sizeof(id))
 		return -EINVAL;
 
@@ -888,6 +895,34 @@ static int mock_health_info(struct cxl_dev_state *cxlds,
 	return 0;
 }
 
+static int mock_get_poison(struct cxl_dev_state *cxlds,
+			   struct cxl_mbox_cmd *cmd)
+{
+	struct cxl_mbox_poison_payload_in *pi = cmd->payload_in;
+
+	/* Mock one poison record at pi.offset for 64 bytes */
+	struct {
+		struct cxl_mbox_poison_payload_out po;
+		struct cxl_poison_record record;
+	} __packed mock_plist = {
+		.po = {
+			.count = cpu_to_le16(1),
+		},
+		.record = {
+			.length = cpu_to_le32(1),
+			.address = cpu_to_le64(le64_to_cpu(pi->offset) +
+					       CXL_POISON_SOURCE_INJECTED),
+		},
+	};
+
+	if (cmd->size_out < sizeof(mock_plist))
+		return -EINVAL;
+
+	memcpy(cmd->payload_out, &mock_plist, sizeof(mock_plist));
+	cmd->size_out = sizeof(mock_plist);
+	return 0;
+}
+
 static int cxl_mock_mbox_send(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd)
 {
 	struct device *dev = cxlds->dev;
@@ -942,6 +977,9 @@ static int cxl_mock_mbox_send(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *
 	case CXL_MBOX_OP_PASSPHRASE_SECURE_ERASE:
 		rc = mock_passphrase_secure_erase(cxlds, cmd);
 		break;
+	case CXL_MBOX_OP_GET_POISON:
+		rc = mock_get_poison(cxlds, cmd);
+		break;
 	default:
 		break;
 	}
@@ -1010,6 +1048,10 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
+	rc = cxl_poison_state_init(cxlds);
+	if (rc)
+		return rc;
+
 	rc = cxl_dev_state_identify(cxlds);
 	if (rc)
 		return rc;
-- 
2.37.3

Re: [PATCH v6 4/6] cxl/region: Provide region info to the cxl_poison trace event

[Jonathan Cameron]

On Thu,  9 Feb 2023 15:32:57 -0800
alison.schofield@intel.com wrote:

> From: Alison Schofield <alison.schofield@intel.com>
> 
> User space may need to know which region, if any, maps the poison
> address(es) logged in a cxl_poison trace event. Since the mapping
> of DPAs (device physical addresses) to a region can change, the
> kernel must provide this information at the time the poison list
> is read. The event informs user space that at event <timestamp>
> this <region> mapped to this <DPA>, which is poisoned.
> 
> The cxl_poison trace event is already wired up to log the region
> name and uuid if it receives param 'struct cxl_region'.
> 
> In order to provide that cxl_region, add another method for gathering
> poison - by committed endpoint decoder mappings. This method is only
> available with CONFIG_CXL_REGION and is only used if a region actually
> maps the memdev where poison is being read. The default method remains:
> read the poison by memdev resource.

Mention here that you also cover memory that isn't mapped.

A few minor comments inline.

Thanks,

Jonathan


> 
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> ---
>  drivers/cxl/core/core.h   |  5 +++
>  drivers/cxl/core/memdev.c | 14 ++++++-
>  drivers/cxl/core/region.c | 82 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 100 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 8c04672dca56..2f9bd8651eb1 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -22,7 +22,12 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled);
>  #define CXL_PMEM_REGION_TYPE(x) (&cxl_pmem_region_type)
>  int cxl_region_init(void);
>  void cxl_region_exit(void);
> +int cxl_get_poison_by_endpoint(struct device *dev, void *data);
>  #else
> +static inline int cxl_get_poison_by_endpoint(struct device *dev, void *data)
> +{
> +	return 0;
> +}
>  static inline void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
>  {
>  }
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index 19b833c9cf35..8696d7b508b6 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -139,14 +139,26 @@ static ssize_t trigger_poison_list_store(struct device *dev,
>  					 const char *buf, size_t len)
>  {
>  	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> +	struct cxl_port *port;
>  	bool trigger;
>  	int rc;
>  
>  	if (kstrtobool(buf, &trigger) || !trigger)
>  		return -EINVAL;
>  
> +	port = dev_get_drvdata(&cxlmd->dev);
> +	if (!port || !is_cxl_endpoint(port))
> +		return -EINVAL;
> +
>  	down_read(&cxl_dpa_rwsem);
> -	rc = cxl_get_poison_by_memdev(cxlmd);
> +	if (port->commit_end == -1)
> +		/* No regions mapped to this memdev */
> +		rc = cxl_get_poison_by_memdev(cxlmd);
> +	else
> +		/* Regions mapped, collect poison by endpoint */
> +		rc = device_for_each_child(&port->dev, port,
> +					   cxl_get_poison_by_endpoint);
> +
>  	up_read(&cxl_dpa_rwsem);
>  
>  	return rc ? rc : len;
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 67e83d961670..0ac08e9106af 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1826,6 +1826,88 @@ struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
>  }
>  EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, CXL);
>  
> +int cxl_get_poison_by_endpoint(struct device *dev, void *data)
> +{
> +	struct cxl_endpoint_decoder *cxled;
> +	struct cxl_port *port = data;
> +	struct cxl_dev_state *cxlds;
> +	struct cxl_memdev *cxlmd;
> +	u64 offset, length;
> +	int rc = 0;
> +
> +	down_read(&cxl_dpa_rwsem);
> +
> +	if (!is_endpoint_decoder(dev))
> +		goto out;
> +
> +	cxled = to_cxl_endpoint_decoder(dev);
> +	if (!cxled->dpa_res || !resource_size(cxled->dpa_res))
> +		goto out;
> +
> +	/*
> +	 * Get the poison by decoder for mapped resources. This
> +	 * separates pmem and ram poison list reads, as the spec
> +	 * requires, and provides the region for the trace event.
> +	 */

Does the spec actually require separate decoders for PMEM and MEM?
Sure, Linux only sets it up like that, but a BIOS might have set
them up as a single decoder I think - even if we don't handle
that form of crazy yet. If the spec requires it, then a reference
would be great.

> +	cxlmd = cxled_to_memdev(cxled);
> +	length = cxled->dpa_res->end - cxled->dpa_res->start + 1;
> +	rc = cxl_mem_get_poison(cxlmd, cxled->dpa_res->start, length,
> +				cxled->cxld.region);
> +	if (rc == -EFAULT && cxled->mode == CXL_DECODER_RAM)
> +		rc = 0;
> +	if (rc)
> +		goto out;
> +
> +	/* Get poison in a skip range */

Seems odd to do it in this order. I'd do the skip first as then
the records will appear in address order (subject to whatever
random order the device is tracking them and the resulting ordering
in each request)

> +	if (cxled->skip) {
> +		rc = cxl_mem_get_poison(cxlmd, 0, cxled->skip, NULL);
> +		if (rc == -EFAULT && cxled->mode == CXL_DECODER_RAM)
> +			rc = 0;
> +		if (rc)
> +			goto out;
> +	}
> +
> +	/* Iterate until commit_end is reached */
> +	if (cxled->cxld.id < port->commit_end)
> +		goto out;
> +
> +	/*
> +	 * Reach here with the last committed decoder only.
> +	 * Knowing that PMEM must always follow RAM, get poison
> +	 * for unmapped ranges based on the last decoder's mode:
> +	 *	ram: scan remains of ram range, then scan for pmem
> +	 *	pmem: scan remains of pmem range
> +	 */
> +	cxlds = cxlmd->cxlds;
> +
> +	if (cxled->mode == CXL_DECODER_RAM) {
> +		offset = cxled->dpa_res->end + 1;
> +		length = resource_size(&cxlds->ram_res) - offset;
> +		rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
> +		if (rc == -EFAULT)
> +			rc = 0;
> +		if (rc)
> +			goto out;
> +	}
> +	if (cxled->mode == CXL_DECODER_PMEM) {
> +		offset = cxled->dpa_res->end + 1;
> +		length = resource_size(&cxlds->pmem_res) - offset;
> +	} else if (resource_size(&cxlds->pmem_res)) {
> +		offset = cxlds->pmem_res.start;
> +		length = resource_size(&cxlds->pmem_res);
> +	} else {
> +		rc = 1;
> +		goto out;
> +	}
> +	/* Final get poison call. Return rc or 1 to stop iteration. */
> +	rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
> +	if (!rc)
> +		rc = 1;
> +out:
> +	up_read(&cxl_dpa_rwsem);
> +	return rc;
> +}
> +
>  static struct lock_class_key cxl_pmem_region_key;
>  
>  static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)

Re: [PATCH v6 4/6] cxl/region: Provide region info to the cxl_poison trace event

[Alison Schofield]

On Fri, Feb 10, 2023 at 12:56:41PM +0000, Jonathan Cameron wrote:
> On Thu,  9 Feb 2023 15:32:57 -0800
> alison.schofield@intel.com wrote:
> 
> > From: Alison Schofield <alison.schofield@intel.com>
> > 
> > User space may need to know which region, if any, maps the poison
> > address(es) logged in a cxl_poison trace event. Since the mapping
> > of DPAs (device physical addresses) to a region can change, the
> > kernel must provide this information at the time the poison list
> > is read. The event informs user space that at event <timestamp>
> > this <region> mapped to this <DPA>, which is poisoned.
> > 
> > The cxl_poison trace event is already wired up to log the region
> > name and uuid if it receives param 'struct cxl_region'.
> > 
> > In order to provide that cxl_region, add another method for gathering
> > poison - by committed endpoint decoder mappings. This method is only
> > available with CONFIG_CXL_REGION and is only used if a region actually
> > maps the memdev where poison is being read. The default method remains:
> > read the poison by memdev resource.
> 
> Mention here that you also cover memory that isn't mapped.
Ok, will do. And will also mention that we don't cover
CXL_DECODER_MIXED, as I'm noting below...

> 
> A few minor comments inline.
> 
> Thanks,
> 
> Jonathan
> 
> 
> > 
> > Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> > ---
> >  drivers/cxl/core/core.h   |  5 +++
> >  drivers/cxl/core/memdev.c | 14 ++++++-
> >  drivers/cxl/core/region.c | 82 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 100 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> > index 8c04672dca56..2f9bd8651eb1 100644
> > --- a/drivers/cxl/core/core.h
> > +++ b/drivers/cxl/core/core.h
> > @@ -22,7 +22,12 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled);
> >  #define CXL_PMEM_REGION_TYPE(x) (&cxl_pmem_region_type)
> >  int cxl_region_init(void);
> >  void cxl_region_exit(void);
> > +int cxl_get_poison_by_endpoint(struct device *dev, void *data);
> >  #else
> > +static inline int cxl_get_poison_by_endpoint(struct device *dev, void *data)
> > +{
> > +	return 0;
> > +}
> >  static inline void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
> >  {
> >  }
> > diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> > index 19b833c9cf35..8696d7b508b6 100644
> > --- a/drivers/cxl/core/memdev.c
> > +++ b/drivers/cxl/core/memdev.c
> > @@ -139,14 +139,26 @@ static ssize_t trigger_poison_list_store(struct device *dev,
> >  					 const char *buf, size_t len)
> >  {
> >  	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
> > +	struct cxl_port *port;
> >  	bool trigger;
> >  	int rc;
> >  
> >  	if (kstrtobool(buf, &trigger) || !trigger)
> >  		return -EINVAL;
> >  
> > +	port = dev_get_drvdata(&cxlmd->dev);
> > +	if (!port || !is_cxl_endpoint(port))
> > +		return -EINVAL;
> > +
> >  	down_read(&cxl_dpa_rwsem);
> > -	rc = cxl_get_poison_by_memdev(cxlmd);
> > +	if (port->commit_end == -1)
> > +		/* No regions mapped to this memdev */
> > +		rc = cxl_get_poison_by_memdev(cxlmd);
> > +	else
> > +		/* Regions mapped, collect poison by endpoint */
> > +		rc = device_for_each_child(&port->dev, port,
> > +					   cxl_get_poison_by_endpoint);
> > +
> >  	up_read(&cxl_dpa_rwsem);
> >  
> >  	return rc ? rc : len;
> > diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> > index 67e83d961670..0ac08e9106af 100644
> > --- a/drivers/cxl/core/region.c
> > +++ b/drivers/cxl/core/region.c
> > @@ -1826,6 +1826,88 @@ struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev)
> >  }
> >  EXPORT_SYMBOL_NS_GPL(to_cxl_pmem_region, CXL);
> >  
> > +int cxl_get_poison_by_endpoint(struct device *dev, void *data)
> > +{
> > +	struct cxl_endpoint_decoder *cxled;
> > +	struct cxl_port *port = data;
> > +	struct cxl_dev_state *cxlds;
> > +	struct cxl_memdev *cxlmd;
> > +	u64 offset, length;
> > +	int rc = 0;
> > +
> > +	down_read(&cxl_dpa_rwsem);
> > +
> > +	if (!is_endpoint_decoder(dev))
> > +		goto out;
> > +
> > +	cxled = to_cxl_endpoint_decoder(dev);
> > +	if (!cxled->dpa_res || !resource_size(cxled->dpa_res))
> > +		goto out;
> > +
> > +	/*
> > +	 * Get the poison by decoder for mapped resources. This
> > +	 * separates pmem and ram poison list reads, as the spec
> > +	 * requires, and provides the region for the trace event.
> > +	 */
> 
> Does the spec actually require separate decoders for PMEM and MEM?
> Sure, Linux only sets it up like that, but a BIOS might have set
> them up as a single decoder I think - even if we don't handle
> that form of crazy yet. If the spec requires it, then a reference
> would be great.
> 

No, the spec allows mixed mode decoders. I chatted w Dan about this,
and we're suggesting skipping poison reads when mode == CXL_DECODER_MIXED.
That skip would be quiet, just a dev_debug(). But, add some more noise
to the front end by changing adding this dev_warn() :

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index dcc16d7cb8f3..349a16b7c97a 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -268,8 +268,8 @@ static int __cxl_dpa_reserve(struct cxl_endpoint_decoder *cxled,
        else if (resource_contains(&cxlds->ram_res, res))
                cxled->mode = CXL_DECODER_RAM;
        else {
-               dev_dbg(dev, "decoder%d.%d: %pr mixed\n", port->id,
-                       cxled->cxld.id, cxled->dpa_res);
+               dev_warn(dev, "decoder%d.%d: %pr mixed mode not supported\n",
+                        port->id, cxled->cxld.id, cxled->dpa_res);
                cxled->mode = CXL_DECODER_MIXED;
        }

> > +	cxlmd = cxled_to_memdev(cxled);
> > +	length = cxled->dpa_res->end - cxled->dpa_res->start + 1;
> > +	rc = cxl_mem_get_poison(cxlmd, cxled->dpa_res->start, length,
> > +				cxled->cxld.region);
> > +	if (rc == -EFAULT && cxled->mode == CXL_DECODER_RAM)
> > +		rc = 0;
> > +	if (rc)
> > +		goto out;
> > +
> > +	/* Get poison in a skip range */
> 
> Seems odd to do it in this order. I'd do the skip first as then
> the records will appear in address order (subject to whatever
> random order the device is tracking them and the resulting ordering
> in each request)
> 
Yes - skip should be logically first, since those addresses would be
before any mapped addresses. Thanks for pointing it out.

> > +	if (cxled->skip) {
> > +		rc = cxl_mem_get_poison(cxlmd, 0, cxled->skip, NULL);
> > +		if (rc == -EFAULT && cxled->mode == CXL_DECODER_RAM)
> > +			rc = 0;
> > +		if (rc)
> > +			goto out;
> > +	}
> > +
> > +	/* Iterate until commit_end is reached */
> > +	if (cxled->cxld.id < port->commit_end)
> > +		goto out;
> > +
> > +	/*
> > +	 * Reach here with the last committed decoder only.
> > +	 * Knowing that PMEM must always follow RAM, get poison
> > +	 * for unmapped ranges based on the last decoder's mode:
> > +	 *	ram: scan remains of ram range, then scan for pmem
> > +	 *	pmem: scan remains of pmem range
> > +	 */
> > +	cxlds = cxlmd->cxlds;
> > +
> > +	if (cxled->mode == CXL_DECODER_RAM) {
> > +		offset = cxled->dpa_res->end + 1;
> > +		length = resource_size(&cxlds->ram_res) - offset;
> > +		rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
> > +		if (rc == -EFAULT)
> > +			rc = 0;
> > +		if (rc)
> > +			goto out;
> > +	}
> > +	if (cxled->mode == CXL_DECODER_PMEM) {
> > +		offset = cxled->dpa_res->end + 1;
> > +		length = resource_size(&cxlds->pmem_res) - offset;
> > +	} else if (resource_size(&cxlds->pmem_res)) {
> > +		offset = cxlds->pmem_res.start;
> > +		length = resource_size(&cxlds->pmem_res);
> > +	} else {
> > +		rc = 1;
> > +		goto out;
> > +	}
> > +	/* Final get poison call. Return rc or 1 to stop iteration. */
> > +	rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
> > +	if (!rc)
> > +		rc = 1;
> > +out:
> > +	up_read(&cxl_dpa_rwsem);
> > +	return rc;
> > +}
> > +
> >  static struct lock_class_key cxl_pmem_region_key;
> >  
> >  static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr)
>