Nouveau - Jan 2024 - [PATCH] nouveau: add command-line GSP-RM registry support

Add the NVreg_RegistryDwords command line parameter, which allows
specifying additional registry keys to be sent to GSP-RM.  This
allows additional configuration, debugging, and experimentation
with GSP-RM, which uses these keys to alter its behavior.

Note that these keys are passed as-is to GSP-RM, and Nouveau does
not parse them.  This is in contrast to the Nvidia driver, which may
parse some of the keys to configure some functionality in concert with
GSP-RM.  Therefore, any keys which also require action by the driver
may not function correctly when passed by Nouveau.  Caveat emptor.

The name and format of NVreg_RegistryDwords is the same as used by
the Nvidia driver, to maintain compatibility.

Signed-off-by: Timur Tabi <ttabi at nvidia.com>
---
 .../gpu/drm/nouveau/include/nvkm/subdev/gsp.h |   6 +
 .../gpu/drm/nouveau/nvkm/subdev/gsp/r535.c    | 275 ++++++++++++++++--
 2 files changed, 257 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
b/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
index d1437c08645f..a19c1e9cc305 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
@@ -211,6 +211,12 @@ struct nvkm_gsp {
 		struct mutex mutex;;
 		struct idr idr;
 	} client_id;
+
+	/* A linked list of registry items. The registry object will be built from it.
*/
+	struct list_head registry_list;
+
+	/* The size of the registry RPC */
+	size_t registry_rpc_size;
 };
 
 static inline bool
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
index 9ee58e2a0eb2..b7a4c2749a55 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
@@ -54,6 +54,8 @@
 #include <nvrm/535.113.01/nvidia/kernel/inc/vgpu/rpc_global_enums.h>
 
 #include <linux/acpi.h>
+#include <linux/ctype.h>
+#include <linux/parser.h>
 
 #define GSP_MSG_MIN_SIZE GSP_PAGE_SIZE
 #define GSP_MSG_MAX_SIZE GSP_PAGE_MIN_SIZE * 16
@@ -1049,52 +1051,277 @@ r535_gsp_rpc_unloading_guest_driver(struct nvkm_gsp
*gsp, bool suspend)
 	return nvkm_gsp_rpc_wr(gsp, rpc, true);
 }
 
+struct registry_list_entry {
+	struct list_head list;
+	size_t name_len;
+	u32 type;
+	u32 data;
+	u32 length;
+	char name[];
+};
+
+/**
+ * add_registry -- adds a registry entry
+ * @name: name of the registry key
+ * @type: type of data (1 = integer)
+ * @data: value
+ * @length: size of data, in bytes
+ *
+ * Adds a registry key/value pair to the registry database.
+ *
+ * Currently, only 32-bit integers (type == 1, length == 4) are supported.
+ *
+ * This function collects the registry information in a linked list.  After
+ * all registry keys have been added, build_registry() is used to create the
+ * RPC data structure.
+ *
+ * registry_rpc_size is a running total of the size of all registry keys.
+ * It's used to avoid having to avoid an O(n) calculation of the total when
+ * the RPC is built.
+ *
+ * Returns 0 on success, or negative error code on error.
+ */
+static int add_registry(struct nvkm_gsp *gsp, const char *name, u32 type, u32
data, u32 length)
+{
+	struct registry_list_entry *reg;
+	size_t nlen = strlen(name) + 1;
+
+	/* Set an arbitrary limit to avoid problems with broken command lines */
+	if (strlen(name) > 64)
+		return -EFBIG;
+
+	reg = kmalloc(sizeof(struct registry_list_entry) + nlen, GFP_KERNEL);
+	if (!reg)
+		return -ENOMEM;
+
+	memcpy(reg->name, name, nlen);
+	reg->name_len = nlen;
+	reg->type = type;
+	reg->data = data;
+	reg->length = length;
+
+	nvkm_debug(&gsp->subdev, "adding GSP-RM registry
'%s=%u'\n", name, data);
+	list_add_tail(&reg->list, &gsp->registry_list);
+	gsp->registry_rpc_size += sizeof(PACKED_REGISTRY_ENTRY) + nlen;
+
+	return 0;
+}
+
+static int add_registry_num(struct nvkm_gsp *gsp, const char *name, u32 value)
+{
+	return add_registry(gsp, name, 1, value, sizeof(u32));
+}
+
+/**
+ * build_registry -- create the registry RPC data
+ * @registry: pointer to the RPC payload to fill
+ *
+ * After all registry key/value pairs have been added, call this function to
+ * build the RPC.
+ *
+ * The registry RPC looks like this:
+ *
+ * +-----------------+
+ * |NvU32 size;      |
+ * |NvU32 numEntries;|
+ * +-----------------+
+ * +---------------------+
+ * |PACKED_REGISTRY_ENTRY|
+ * +---------------------+
+ * |PACKED_REGISTRY_ENTRY|
+ * +---------------------+
+ * ... (one copy for each entry)
+ *
+ * +----------------------------------+
+ * |Null-terminated string for entry 0|
+ * +----------------------------------+
+ * |Null-terminated string for entry 1|
+ * +----------------------------------+
+ * ... (one copy for each entry)
+ *
+ * All memory allocated by add_registry() is released.
+ */
+static void build_registry(struct nvkm_gsp *gsp, PACKED_REGISTRY_TABLE
*registry)
+{
+	struct registry_list_entry *reg, *n;
+	size_t str_offset;
+	unsigned int i = 0;
+
+	registry->numEntries = list_count_nodes(&gsp->registry_list);
+	str_offset = struct_size(registry, entries, registry->numEntries);
+
+	list_for_each_entry_safe(reg, n, &gsp->registry_list, list) {
+		registry->entries[i].type = reg->type;
+		registry->entries[i].data = reg->data;
+		registry->entries[i].length = reg->length;
+		registry->entries[i].nameOffset = str_offset;
+		memcpy((void *)registry + str_offset, reg->name, reg->name_len);
+		str_offset += reg->name_len;
+		i++;
+
+		list_del(&reg->list);
+		kfree(reg);
+	}
+
+	/* Double-check that we calculated the sizes correctly */
+	WARN_ON(gsp->registry_rpc_size != str_offset);
+
+	registry->size = gsp->registry_rpc_size;
+}
+
+/**
+ * clean_registry -- clean up registry memory in case of error
+ *
+ * Call this function to clean up all memory allocated by add_registry()
+ * in case of error and build_registry() is not called.
+ */
+static void clean_registry(struct nvkm_gsp *gsp)
+{
+	struct registry_list_entry *reg, *n;
+
+	list_for_each_entry_safe(reg, n, &gsp->registry_list, list) {
+		list_del(&reg->list);
+		kfree(reg);
+	}
+
+	gsp->registry_rpc_size = sizeof(PACKED_REGISTRY_TABLE);
+}
+
+MODULE_PARM_DESC(NVreg_RegistryDwords,
+		 "A semicolon-separated list of key=integer pairs of registry keys
passed to GSP-RM");
+static char *NVreg_RegistryDwords;
+module_param(NVreg_RegistryDwords, charp, 0400);
+
 /* dword only */
 struct nv_gsp_registry_entries {
 	const char *name;
 	u32 value;
 };
 
+/**
+ * r535_registry_entries - required registry entries for GSP-RM
+ *
+ * This struct lists registry entries that are required for GSP-RM to
+ * function correctly.
+ *
+ * RMSecBusResetEnable - enables PCI secondary bus reset
+ * RMForcePcieConfigSave - forces GSP-RM to preserve PCI configuration
+ *   registers on any PCI reset.
+ */
 static const struct nv_gsp_registry_entries r535_registry_entries[] = {
 	{ "RMSecBusResetEnable", 1 },
 	{ "RMForcePcieConfigSave", 1 },
 };
 #define NV_GSP_REG_NUM_ENTRIES ARRAY_SIZE(r535_registry_entries)
 
+/**
+ * strip - strips all characters in 'reject' from 's'
+ * @s: string to strip
+ * @reject: string of characters to remove
+ *
+ * 's' is modified.
+ *
+ * Returns the length of the new string.
+ */
+static size_t strip(char *s, const char *reject)
+{
+	char *p = s, *p2 = s;
+	size_t length = 0;
+	char c;
+
+	do {
+		while ((c = *p2) && strchr(reject, c))
+			p2++;
+
+		*p++ = c = *p2++;
+		length++;
+	} while (c);
+
+	return length;
+}
+
+/**
+ * r535_gsp_rpc_set_registry - build registry RPC and call GSP-RM
+ * @gsp: gsp object
+ *
+ * The GSP-RM registry is a set of key/value pairs that configure some aspects
+ * of GSP-RM. The keys are strings, and the values are 32-bit integers.
+ *
+ * The registry is built from a combination if a static hard-coded list (see
+ * above) and entries passed on the driver's command line.
+ */
 static int
 r535_gsp_rpc_set_registry(struct nvkm_gsp *gsp)
 {
 	PACKED_REGISTRY_TABLE *rpc;
-	char *strings;
-	int str_offset;
-	int i;
-	size_t rpc_size = struct_size(rpc, entries, NV_GSP_REG_NUM_ENTRIES);
+	unsigned int i;
+	int ret;
 
-	/* add strings + null terminator */
-	for (i = 0; i < NV_GSP_REG_NUM_ENTRIES; i++)
-		rpc_size += strlen(r535_registry_entries[i].name) + 1;
+	INIT_LIST_HEAD(&gsp->registry_list);
+	gsp->registry_rpc_size = sizeof(PACKED_REGISTRY_TABLE);
 
-	rpc = nvkm_gsp_rpc_get(gsp, NV_VGPU_MSG_FUNCTION_SET_REGISTRY, rpc_size);
-	if (IS_ERR(rpc))
-		return PTR_ERR(rpc);
+	/* Add the required registry entries now */
+	for (i = 0; i < NV_GSP_REG_NUM_ENTRIES; i++) {
+		ret = add_registry_num(gsp, r535_registry_entries[i].name,
+				 r535_registry_entries[i].value);
+		if (ret) {
+			clean_registry(gsp);
+			return ret;
+		}
+	}
 
-	rpc->size = sizeof(*rpc);
-	rpc->numEntries = NV_GSP_REG_NUM_ENTRIES;
+	/*
+	 * The NVreg_RegistryDwords parameter is a string of key=value
+	 * pairs separated by semicolons. We need to extract and trim each
+	 * substring, and then parse the substring to extract the key and
+	 * value.
+	 */
+	if (NVreg_RegistryDwords) {
+		char *p = kstrdup(NVreg_RegistryDwords, GFP_KERNEL);
+		char *start, *next = p, *equal;
+		size_t length;
+
+		/* Remove any whitespace from the parameter string */
+		length = strip(p, " \t\n");
+
+		while ((start = strsep(&next, ";"))) {
+			long value;
+
+			equal = strchr(start, '=');
+			if (!equal || (equal == start) || !isdigit(equal[1])) {
+				nvkm_error(&gsp->subdev,
+					"ignoring invalid registry string '%s'\n", start);
+				continue;
+			}
 
-	str_offset = offsetof(typeof(*rpc), entries[NV_GSP_REG_NUM_ENTRIES]);
-	strings = (char *)&rpc->entries[NV_GSP_REG_NUM_ENTRIES];
-	for (i = 0; i < NV_GSP_REG_NUM_ENTRIES; i++) {
-		int name_len = strlen(r535_registry_entries[i].name) + 1;
-
-		rpc->entries[i].nameOffset = str_offset;
-		rpc->entries[i].type = 1;
-		rpc->entries[i].data = r535_registry_entries[i].value;
-		rpc->entries[i].length = 4;
-		memcpy(strings, r535_registry_entries[i].name, name_len);
-		strings += name_len;
-		str_offset += name_len;
+			ret = kstrtol(equal + 1, 0, &value);
+			if (ret) {
+				nvkm_error(&gsp->subdev,
+					"ignoring invalid registry value in '%s'\n", start);
+				continue;
+			}
+
+			/* Truncate the key=value string to just key */
+			*equal = 0;
+
+			ret = add_registry_num(gsp, start, value);
+			if (ret) {
+				nvkm_error(&gsp->subdev,
+					"ignoring invalid registry key/value '%s=%lu'\n",
+					start, value);
+				continue;
+			}
+		}
+
+		kfree(p);
 	}
 
+	rpc = nvkm_gsp_rpc_get(gsp, NV_VGPU_MSG_FUNCTION_SET_REGISTRY,
gsp->registry_rpc_size);
+	if (IS_ERR(rpc))
+		return PTR_ERR(rpc);
+
+	build_registry(gsp, rpc);
+
 	return nvkm_gsp_rpc_wr(gsp, rpc, false);
 }
 
-- 
2.34.1