cxl/mem: Read, trace, and clear events on driver load

CXL devices have multiple event logs which can be queried for CXL event
records.  Devices are required to support the storage of at least one
event record in each event log type.

Devices track event log overflow by incrementing a counter and tracking
the time of the first and last overflow event seen.

Software queries events via the Get Event Record mailbox command; CXL
rev 3.0 section 8.2.9.2.2 and clears events via CXL rev 3.0 section
8.2.9.2.3 Clear Event Records mailbox command.

If the result of negotiating CXL Error Reporting Control is OS control,
read and clear all event logs on driver load.

Ensure a clean slate of events by reading and clearing the events on
driver load.

The status register is not used because a device may continue to trigger
events and the only requirement is to empty the log at least once.  This
allows for the required transition from empty to non-empty for interrupt
generation.  Handling of interrupts is in a follow on patch.

The device can return up to 1MB worth of event records per query.
Allocate a shared large buffer to handle the max number of records based
on the mailbox payload size.

This patch traces a raw event record and leaves specific event record
type tracing to subsequent patches.  Macros are created to aid in
tracing the common CXL Event header fields.

Each record is cleared explicitly.  A clear all bit is specified but is
only valid when the log overflows.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20221216-cxl-ev-log-v7-1-2316a5c8f7d8@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 2bbebbc7e032..0a24bc7da1e4 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -417,8 +417,30 @@ static void disable_aer(void *pdev)
 	pci_disable_pcie_error_reporting(pdev);
 }
 
+static void free_event_buf(void *buf)
+{
+	kvfree(buf);
+}
+
+/*
+ * There is a single buffer for reading event logs from the mailbox.  All logs
+ * share this buffer protected by the cxlds->event_log_lock.
+ */
+static int cxl_mem_alloc_event_buf(struct cxl_dev_state *cxlds)
+{
+	struct cxl_get_event_payload *buf;
+
+	buf = kvmalloc(cxlds->payload_size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	cxlds->event.buf = buf;
+
+	return devm_add_action_or_reset(cxlds->dev, free_event_buf, buf);
+}
+
 static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 {
+	struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
 	struct cxl_register_map map;
 	struct cxl_memdev *cxlmd;
 	struct cxl_dev_state *cxlds;
@@ -494,6 +516,17 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (IS_ERR(cxlmd))
 		return PTR_ERR(cxlmd);
 
+	/*
+	 * When BIOS maintains CXL error reporting control, it will process
+	 * event records.  Only one agent can do so.
+	 */
+	if (host_bridge->native_cxl_error) {
+		rc = cxl_mem_alloc_event_buf(cxlds);
+		if (rc)
+			return rc;
+		cxl_mem_get_event_records(cxlds, CXLDEV_EVENT_STATUS_ALL);
+	}
+
 	if (cxlds->regs.ras) {
 		pci_enable_pcie_error_reporting(pdev);
 		rc = devm_add_action_or_reset(&pdev->dev, disable_aer, pdev);