Nouveau - Apr 2024 - [PATCH] [v5] 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>
---
v5:
Add REGISTRY_MAX_KEY_LENGTH
registry_list_entry.key is now char[64] instead of char *
use strnlen instead of strlen
removed some debug printks
fixed most checkpatch complaints
rebased to drm-fixes

 .../gpu/drm/nouveau/include/nvkm/subdev/gsp.h |   6 +
 .../gpu/drm/nouveau/nvkm/subdev/gsp/r535.c    | 360 ++++++++++++++++--
 2 files changed, 342 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 6f5d376d8fcc..3fbc57b16a05 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 RPC 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 9858c1438aa7..981ddd0fb1e7 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
@@ -1080,51 +1082,361 @@ r535_gsp_rpc_unloading_guest_driver(struct nvkm_gsp
*gsp, bool suspend)
 	return nvkm_gsp_rpc_wr(gsp, rpc, true);
 }
 
+enum registry_type {
+	REGISTRY_TABLE_ENTRY_TYPE_DWORD  = 1, /* 32-bit unsigned integer */
+	REGISTRY_TABLE_ENTRY_TYPE_BINARY = 2, /* Binary blob */
+	REGISTRY_TABLE_ENTRY_TYPE_STRING = 3, /* Null-terminated string */
+};
+
+/* An arbitrary limit to the length of a registry key */
+#define REGISTRY_MAX_KEY_LENGTH		64
+
+/**
+ * registry_list_entry - linked list member for a registry key/value
+ * @head: list_head struct
+ * @type: dword, binary, or string
+ * @klen: the length of name of the key
+ * @vlen: the length of the value
+ * @v.dword: the data, if REGISTRY_TABLE_ENTRY_TYPE_DWORD
+ * @v.binary: the data, if TYPE_BINARY or TYPE_STRING
+ * @key: the key name
+ *
+ * Every registry key/value is represented internally by this struct.
+ *
+ * Type DWORD is a simple 32-bit unsigned integer, and its value is stored in
+ * v.dword.
+ *
+ * Types BINARY and STRING are variable-length binary blobs.  The only real
+ * difference between BINARY and STRING is that STRING is null-terminated and
+ * is expected to contain only printable characters.
+ *
+ * To avoid having to kmalloc multiple objects, the value for BINARY and
+ * STRING is appended after the key[] in memory, and v.binary just points to
+ * that block.
+ *
+ * Note: it is technically possible to have multiple keys with the same name
+ * but different types, but this is not useful since GSP-RM expects keys to
+ * have only one specific type.
+ */
+struct registry_list_entry {
+	struct list_head head;
+	enum registry_type type;
+	size_t klen;
+	size_t vlen;
+	char key[REGISTRY_MAX_KEY_LENGTH] __counted_by(klen);
+	u32 dword;				/* TYPE_DWORD */
+	u8 binary[] __counted_by(vlen);	/* TYPE_BINARY or TYPE_STRING */
+};
+
+/**
+ * add_registry -- adds a registry entry
+ * @gsp: gsp pointer
+ * @key: name of the registry key
+ * @type: type of data
+ * @data: pointer to value
+ * @length: size of data, in bytes
+ *
+ * Adds a registry key/value pair to the registry database.
+ *
+ * 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 an O(n) calculation of the size 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 *key,
+			enum registry_type type, const void *data, size_t length)
+{
+	struct registry_list_entry *reg;
+	size_t nlen = strnlen(key, REGISTRY_MAX_KEY_LENGTH) + 1;
+	size_t vlen; /* value length, non-zero if binary or string */
+
+	if (nlen > REGISTRY_MAX_KEY_LENGTH)
+		return -EFBIG;
+
+	vlen = (type == REGISTRY_TABLE_ENTRY_TYPE_DWORD) ? 0 : length;
+
+	reg = kmalloc(sizeof(*reg) + vlen, GFP_KERNEL);
+	if (!reg)
+		return -ENOMEM;
+
+	switch (type) {
+	case REGISTRY_TABLE_ENTRY_TYPE_DWORD:
+		reg->dword = *(const u32 *)(data);
+		break;
+	case REGISTRY_TABLE_ENTRY_TYPE_BINARY:
+	case REGISTRY_TABLE_ENTRY_TYPE_STRING:
+		memcpy(reg->binary, data, length);
+		break;
+	default:
+		nvkm_error(&gsp->subdev, "unrecognized registry type %u for
'%s'\n",
+			   type, key);
+		kfree(reg);
+		return -EINVAL;
+	}
+
+	memcpy(reg->key, key, nlen);
+	reg->klen = nlen;
+	reg->vlen = length;
+	reg->type = type;
+
+	list_add_tail(&reg->head, &gsp->registry_list);
+	gsp->registry_rpc_size += sizeof(PACKED_REGISTRY_ENTRY) + nlen + vlen;
+
+	return 0;
+}
+
+static int add_registry_num(struct nvkm_gsp *gsp, const char *key, u32 value)
+{
+	return add_registry(gsp, key, REGISTRY_TABLE_ENTRY_TYPE_DWORD,
+			    &value, sizeof(u32));
+}
+
+static int add_registry_string(struct nvkm_gsp *gsp, const char *key, const
char *value)
+{
+	return add_registry(gsp, key, REGISTRY_TABLE_ENTRY_TYPE_STRING,
+			    value, strlen(value) + 1);
+}
+
+/**
+ * build_registry -- create the registry RPC data
+ * @gsp: gsp pointer
+ * @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 key (string) for entry 0|
+ * +----------------------------------------+
+ * |Binary/string data value for entry 0    | (only if necessary)
+ * +----------------------------------------+
+ * |Null-terminated key (string) for entry 1|
+ * +----------------------------------------+
+ * |Binary/string data value for entry 1    | (only if necessary)
+ * +----------------------------------------+
+ * ... (one copy for each entry)
+ *
+ *
+ * The 'data' field of an entry is either a 32-bit integer (for type
DWORD)
+ * or an offset into the PACKED_REGISTRY_TABLE (for types BINARY and STRING).
+ *
+ * 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, head) {
+		registry->entries[i].type = reg->type;
+		registry->entries[i].length = reg->klen;
+
+		/* Append the key name to the table */
+		registry->entries[i].nameOffset = str_offset;
+		memcpy((void *)registry + str_offset, reg->key, reg->klen);
+		str_offset += reg->klen;
+
+		switch (reg->type) {
+		case REGISTRY_TABLE_ENTRY_TYPE_DWORD:
+			registry->entries[i].data = reg->dword;
+			break;
+		case REGISTRY_TABLE_ENTRY_TYPE_BINARY:
+		case REGISTRY_TABLE_ENTRY_TYPE_STRING:
+			/* If the type is binary or string, also append the value */
+			memcpy((void *)registry + str_offset, reg->binary, reg->vlen);
+			registry->entries[i].data = str_offset;
+			str_offset += reg->vlen;
+			break;
+		default:
+		}
+
+		i++;
+		list_del(&reg->head);
+		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
+ * @gsp: gsp pointer
+ *
+ * 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, head) {
+		list_del(&reg->head);
+		kfree(reg);
+	}
+
+	gsp->registry_rpc_size = sizeof(PACKED_REGISTRY_TABLE);
+}
+
+MODULE_PARM_DESC(NVreg_RegistryDwords,
+		 "A semicolon-separated list of key=integer pairs of GSP-RM registry
keys");
+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 array 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 pointer
+ *
+ * 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 of 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);
+	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->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 || equal[1] == 0) {
+				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 + str_offset;
-	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;
+			/* Truncate the key=value string to just key */
+			*equal = 0;
+
+			ret = kstrtol(equal + 1, 0, &value);
+			if (!ret) {
+				ret = add_registry_num(gsp, start, value);
+			} else {
+				/* Not a number, so treat it as a string */
+				ret = add_registry_string(gsp, start, equal + 1);
+			}
+
+			if (ret) {
+				nvkm_error(&gsp->subdev,
+					   "ignoring invalid registry key/value '%s=%s'\n",
+					   start, equal + 1);
+				continue;
+			}
+		}
+
+		kfree(p);
 	}
-	rpc->size = str_offset;
+
+	rpc = nvkm_gsp_rpc_get(gsp, NV_VGPU_MSG_FUNCTION_SET_REGISTRY,
gsp->registry_rpc_size);
+	if (IS_ERR(rpc)) {
+		clean_registry(gsp);
+		return PTR_ERR(rpc);
+	}
+
+	build_registry(gsp, rpc);
 
 	return nvkm_gsp_rpc_wr(gsp, rpc, false);
 }
-- 
2.34.1

On Tue, Apr 09, 2024 at 06:15:52PM -0500, Timur Tabi
wrote:
> 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>
> ---
> v5:
> Add REGISTRY_MAX_KEY_LENGTH
> registry_list_entry.key is now char[64] instead of char *
> use strnlen instead of strlen
> removed some debug printks
> fixed most checkpatch complaints
> rebased to drm-fixes
This patch seems to be based on drm-misc-fixes instead. For this patch the
correct target branch would be drm-misc-next though.

You can, additionally, use '--base' when running git format-patch. This
will
include the hash of the base commit.
> 
>  .../gpu/drm/nouveau/include/nvkm/subdev/gsp.h |   6 +
>  .../gpu/drm/nouveau/nvkm/subdev/gsp/r535.c    | 360 ++++++++++++++++--
>  2 files changed, 342 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 6f5d376d8fcc..3fbc57b16a05 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 RPC 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 9858c1438aa7..981ddd0fb1e7 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
> @@ -1080,51 +1082,361 @@ r535_gsp_rpc_unloading_guest_driver(struct
nvkm_gsp *gsp, bool suspend)
>  	return nvkm_gsp_rpc_wr(gsp, rpc, true);
>  }
>  
> +enum registry_type {
> +	REGISTRY_TABLE_ENTRY_TYPE_DWORD  = 1, /* 32-bit unsigned integer */
> +	REGISTRY_TABLE_ENTRY_TYPE_BINARY = 2, /* Binary blob */
> +	REGISTRY_TABLE_ENTRY_TYPE_STRING = 3, /* Null-terminated string */
> +};
> +
> +/* An arbitrary limit to the length of a registry key */
> +#define REGISTRY_MAX_KEY_LENGTH		64
> +
> +/**
> + * registry_list_entry - linked list member for a registry key/value
> + * @head: list_head struct
> + * @type: dword, binary, or string
> + * @klen: the length of name of the key
> + * @vlen: the length of the value
> + * @v.dword: the data, if REGISTRY_TABLE_ENTRY_TYPE_DWORD
> + * @v.binary: the data, if TYPE_BINARY or TYPE_STRING
> + * @key: the key name
> + *
> + * Every registry key/value is represented internally by this struct.
> + *
> + * Type DWORD is a simple 32-bit unsigned integer, and its value is stored
in
> + * v.dword.
> + *
> + * Types BINARY and STRING are variable-length binary blobs.  The only
real
> + * difference between BINARY and STRING is that STRING is null-terminated
and
> + * is expected to contain only printable characters.
> + *
> + * To avoid having to kmalloc multiple objects, the value for BINARY and
> + * STRING is appended after the key[] in memory, and v.binary just points
to
> + * that block.
> + *
> + * Note: it is technically possible to have multiple keys with the same
name
> + * but different types, but this is not useful since GSP-RM expects keys
to
> + * have only one specific type.
> + */
> +struct registry_list_entry {
> +	struct list_head head;
> +	enum registry_type type;
> +	size_t klen;
> +	size_t vlen;
> +	char key[REGISTRY_MAX_KEY_LENGTH] __counted_by(klen);
Now that this is an array, we should remove the __counted_by() annotation.
> +	u32 dword;				/* TYPE_DWORD */
> +	u8 binary[] __counted_by(vlen);	/* TYPE_BINARY or TYPE_STRING */
NIT: Can't we put these two into a union?
> +};
> +
> +/**
> + * add_registry -- adds a registry entry
> + * @gsp: gsp pointer
> + * @key: name of the registry key
> + * @type: type of data
> + * @data: pointer to value
> + * @length: size of data, in bytes
> + *
> + * Adds a registry key/value pair to the registry database.
> + *
> + * 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 an O(n) calculation of the size 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 *key,
> +			enum registry_type type, const void *data, size_t length)
> +{
> +	struct registry_list_entry *reg;
> +	size_t nlen = strnlen(key, REGISTRY_MAX_KEY_LENGTH) + 1;
Guess the only reason for strnlen() here is that you want to stop counting once
you exceed REGISTRY_MAX_KEY_LENGTH anyway, right?
> +	size_t vlen; /* value length, non-zero if binary or string */
> +
> +	if (nlen > REGISTRY_MAX_KEY_LENGTH)
> +		return -EFBIG;
Still prefer EINVAL, EFBIG doesn't really apply here.
> +
> +	vlen = (type == REGISTRY_TABLE_ENTRY_TYPE_DWORD) ? 0 : length;
> +
> +	reg = kmalloc(sizeof(*reg) + vlen, GFP_KERNEL);
> +	if (!reg)
> +		return -ENOMEM;
> +
> +	switch (type) {
> +	case REGISTRY_TABLE_ENTRY_TYPE_DWORD:
> +		reg->dword = *(const u32 *)(data);
> +		break;
> +	case REGISTRY_TABLE_ENTRY_TYPE_BINARY:
> +	case REGISTRY_TABLE_ENTRY_TYPE_STRING:
> +		memcpy(reg->binary, data, length);
Prefer to use vlen here...
> +		break;
> +	default:
> +		nvkm_error(&gsp->subdev, "unrecognized registry type %u for
'%s'\n",
> +			   type, key);
> +		kfree(reg);
> +		return -EINVAL;
> +	}
> +
> +	memcpy(reg->key, key, nlen);
> +	reg->klen = nlen;
> +	reg->vlen = length;
...and here.
> +	reg->type = type;
> +
> +	list_add_tail(&reg->head, &gsp->registry_list);
> +	gsp->registry_rpc_size += sizeof(PACKED_REGISTRY_ENTRY) + nlen + vlen;
> +
> +	return 0;
> +}
> +
> +static int add_registry_num(struct nvkm_gsp *gsp, const char *key, u32
value)
> +{
> +	return add_registry(gsp, key, REGISTRY_TABLE_ENTRY_TYPE_DWORD,
> +			    &value, sizeof(u32));
> +}
> +
> +static int add_registry_string(struct nvkm_gsp *gsp, const char *key,
const char *value)
> +{
> +	return add_registry(gsp, key, REGISTRY_TABLE_ENTRY_TYPE_STRING,
> +			    value, strlen(value) + 1);
> +}
> +
> +/**
> + * build_registry -- create the registry RPC data
> + * @gsp: gsp pointer
> + * @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 key (string) for entry 0|
> + * +----------------------------------------+
> + * |Binary/string data value for entry 0    | (only if necessary)
> + * +----------------------------------------+
> + * |Null-terminated key (string) for entry 1|
> + * +----------------------------------------+
> + * |Binary/string data value for entry 1    | (only if necessary)
> + * +----------------------------------------+
> + * ... (one copy for each entry)
> + *
> + *
> + * The 'data' field of an entry is either a 32-bit integer (for
type DWORD)
> + * or an offset into the PACKED_REGISTRY_TABLE (for types BINARY and
STRING).
> + *
> + * 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, head) {
> +		registry->entries[i].type = reg->type;
> +		registry->entries[i].length = reg->klen;
> +
> +		/* Append the key name to the table */
> +		registry->entries[i].nameOffset = str_offset;
> +		memcpy((void *)registry + str_offset, reg->key, reg->klen);
> +		str_offset += reg->klen;
> +
> +		switch (reg->type) {
> +		case REGISTRY_TABLE_ENTRY_TYPE_DWORD:
> +			registry->entries[i].data = reg->dword;
> +			break;
> +		case REGISTRY_TABLE_ENTRY_TYPE_BINARY:
> +		case REGISTRY_TABLE_ENTRY_TYPE_STRING:
> +			/* If the type is binary or string, also append the value */
> +			memcpy((void *)registry + str_offset, reg->binary, reg->vlen);
> +			registry->entries[i].data = str_offset;
> +			str_offset += reg->vlen;
> +			break;
> +		default:
> +		}
> +
> +		i++;
> +		list_del(&reg->head);
> +		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
> + * @gsp: gsp pointer
> + *
> + * 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, head) {
> +		list_del(&reg->head);
> +		kfree(reg);
> +	}
> +
> +	gsp->registry_rpc_size = sizeof(PACKED_REGISTRY_TABLE);
> +}
> +
> +MODULE_PARM_DESC(NVreg_RegistryDwords,
> +		 "A semicolon-separated list of key=integer pairs of GSP-RM
registry keys");
> +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 array 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 pointer
> + *
> + * 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 of 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);
> +	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->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 || equal[1] == 0) {
> +				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 + str_offset;
> -	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;
> +			/* Truncate the key=value string to just key */
> +			*equal = 0;
> +
> +			ret = kstrtol(equal + 1, 0, &value);
> +			if (!ret) {
> +				ret = add_registry_num(gsp, start, value);
> +			} else {
> +				/* Not a number, so treat it as a string */
> +				ret = add_registry_string(gsp, start, equal + 1);
> +			}
> +
> +			if (ret) {
> +				nvkm_error(&gsp->subdev,
> +					   "ignoring invalid registry key/value '%s=%s'\n",
> +					   start, equal + 1);
> +				continue;
> +			}
> +		}
> +
> +		kfree(p);
>  	}
> -	rpc->size = str_offset;
> +
> +	rpc = nvkm_gsp_rpc_get(gsp, NV_VGPU_MSG_FUNCTION_SET_REGISTRY,
gsp->registry_rpc_size);
> +	if (IS_ERR(rpc)) {
> +		clean_registry(gsp);
> +		return PTR_ERR(rpc);
> +	}
> +
> +	build_registry(gsp, rpc);
>  
>  	return nvkm_gsp_rpc_wr(gsp, rpc, false);
>  }
> -- 
> 2.34.1
>