cxl/mbox: Initialize the poison state

Driver 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). The
driver maintains state information to achieve this goal.

To initialize the state, first recognize the poison commands in
the CEL (Command Effects Log). If the device supports Get Poison
List, allocate a single buffer for the poison list and protect it
with a lock.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/9078d180769be28a5087288b38cdfc827cae58bf.1681838291.git.alison.schofield@intel.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 79 insertions, 2 deletions

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index fd1026970d3a..17737386283a 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -5,6 +5,7 @@
 #include <linux/debugfs.h>
 #include <linux/ktime.h>
 #include <linux/mutex.h>
+#include <cxlpci.h>
 #include <cxlmem.h>
 #include <cxl.h>
 
@@ -120,6 +121,43 @@ static bool cxl_is_security_command(u16 opcode)
 	return false;
 }
 
+static bool cxl_is_poison_command(u16 opcode)
+{
+#define CXL_MBOX_OP_POISON_CMDS 0x43
+
+	if ((opcode >> 8) == CXL_MBOX_OP_POISON_CMDS)
+		return true;
+
+	return false;
+}
+
+static void cxl_set_poison_cmd_enabled(struct cxl_poison_state *poison,
+				       u16 opcode)
+{
+	switch (opcode) {
+	case CXL_MBOX_OP_GET_POISON:
+		set_bit(CXL_POISON_ENABLED_LIST, poison->enabled_cmds);
+		break;
+	case CXL_MBOX_OP_INJECT_POISON:
+		set_bit(CXL_POISON_ENABLED_INJECT, poison->enabled_cmds);
+		break;
+	case CXL_MBOX_OP_CLEAR_POISON:
+		set_bit(CXL_POISON_ENABLED_CLEAR, poison->enabled_cmds);
+		break;
+	case CXL_MBOX_OP_GET_SCAN_MEDIA_CAPS:
+		set_bit(CXL_POISON_ENABLED_SCAN_CAPS, poison->enabled_cmds);
+		break;
+	case CXL_MBOX_OP_SCAN_MEDIA:
+		set_bit(CXL_POISON_ENABLED_SCAN_MEDIA, poison->enabled_cmds);
+		break;
+	case CXL_MBOX_OP_GET_SCAN_MEDIA:
+		set_bit(CXL_POISON_ENABLED_SCAN_RESULTS, poison->enabled_cmds);
+		break;
+	default:
+		break;
+	}
+}
+
 static struct cxl_mem_command *cxl_mem_find_command(u16 opcode)
 {
 	struct cxl_mem_command *c;
@@ -635,13 +673,18 @@ static void cxl_walk_cel(struct cxl_dev_state *cxlds, size_t size, u8 *cel)
 		u16 opcode = le16_to_cpu(cel_entry[i].opcode);
 		struct cxl_mem_command *cmd = cxl_mem_find_command(opcode);
 
-		if (!cmd) {
+		if (!cmd && !cxl_is_poison_command(opcode)) {
 			dev_dbg(cxlds->dev,
 				"Opcode 0x%04x unsupported by driver\n", opcode);
 			continue;
 		}
 
-		set_bit(cmd->info.id, cxlds->enabled_cmds);
+		if (cmd)
+			set_bit(cmd->info.id, cxlds->enabled_cmds);
+
+		if (cxl_is_poison_command(opcode))
+			cxl_set_poison_cmd_enabled(&cxlds->poison, opcode);
+
 		dev_dbg(cxlds->dev, "Opcode 0x%04x enabled\n", opcode);
 	}
 }
@@ -1108,6 +1151,40 @@ int cxl_set_timestamp(struct cxl_dev_state *cxlds)
 }
 EXPORT_SYMBOL_NS_GPL(cxl_set_timestamp, CXL);
 
+static void free_poison_buf(void *buf)
+{
+	kvfree(buf);
+}
+
+/* Get Poison List output buffer is protected by cxlds->poison.lock */
+static int cxl_poison_alloc_buf(struct cxl_dev_state *cxlds)
+{
+	cxlds->poison.list_out = kvmalloc(cxlds->payload_size, GFP_KERNEL);
+	if (!cxlds->poison.list_out)
+		return -ENOMEM;
+
+	return devm_add_action_or_reset(cxlds->dev, free_poison_buf,
+					cxlds->poison.list_out);
+}
+
+int cxl_poison_state_init(struct cxl_dev_state *cxlds)
+{
+	int rc;
+
+	if (!test_bit(CXL_POISON_ENABLED_LIST, cxlds->poison.enabled_cmds))
+		return 0;
+
+	rc = cxl_poison_alloc_buf(cxlds);
+	if (rc) {
+		clear_bit(CXL_POISON_ENABLED_LIST, cxlds->poison.enabled_cmds);
+		return rc;
+	}
+
+	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;