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Fri, 9 Jan 2026 20:57:35 +0000 Date: Fri, 9 Jan 2026 15:57:28 -0500 From: Rodrigo Vivi To: Zack McKevitt CC: Riana Tauro , Jakub Kicinski , , , , , , , , , , , , , Lijo Lazar , Hawking Zhang , "David S. 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We are still supportive of > this functionality making it into the DRM subsystem but have a couple of > questions. > > > On Fri, Dec 05, 2025 at 02:09:33PM +0530, Riana Tauro wrote: > > > From: Rodrigo Vivi > > > > > > Introduces the DRM RAS infrastructure over generic netlink. > > > > > > The new interface allows drivers to expose RAS nodes and their > > > associated error counters to userspace in a structured and extensible > > > way. Each drm_ras node can register its own set of error counters, which > > > are then discoverable and queryable through netlink operations. This > > > lays the groundwork for reporting and managing hardware error states > > > in a unified manner across different DRM drivers. > > > > > > Currently is only supports error-counter nodes. But it can be > > > extended later. > > > > > > The registration is also no tied to any drm node, so it can be > > > used by accel devices as well. > > Thank you for including the userspace reference implementation. I have > begun prototyping an extension for our qaic accel driver to incorporate > telemetry functionality by adding a new node type to drm_ras. Overall, > extending the interface is intuitive. making it extensible was one of the main goals here... > > > > > > > It uses the new and mandatory YAML description format stored in > > > Documentation/netlink/specs/. This forces a single generic netlink > > > family namespace for the entire drm: "drm-ras". > > > But multiple-endpoints are supported within the single family. > > > > > > Any modification to this API needs to be applied to > > > Documentation/netlink/specs/drm_ras.yaml before regenerating the > > > code: > > > > > > $ tools/net/ynl/pyynl/ynl_gen_c.py --spec \ > > > Documentation/netlink/specs/drm_ras.yaml --mode uapi --header \ > > > > include/uapi/drm/drm_ras.h > > > > > > $ tools/net/ynl/pyynl/ynl_gen_c.py --spec \ > > > Documentation/netlink/specs/drm_ras.yaml --mode kernel --header \ > > > > include/drm/drm_ras_nl.h > > > > > > $ tools/net/ynl/pyynl/ynl_gen_c.py --spec \ > > > Documentation/netlink/specs/drm_ras.yaml --mode kernel --source \ > > > > drivers/gpu/drm/drm_ras_nl.c > > > > > > Cc: Zack McKevitt > > > Cc: Lukas Wunner > > > Cc: Lijo Lazar > > > Cc: Hawking Zhang > > > Cc: Jakub Kicinski > > > Cc: David S. Miller > > > Cc: Paolo Abeni > > > Cc: Eric Dumazet > > > Cc: netdev@vger.kernel.org > > > Co-developed-by: Aravind Iddamsetty > > > Signed-off-by: Aravind Iddamsetty > > > Signed-off-by: Rodrigo Vivi > > > Signed-off-by: Riana Tauro > > > --- > > > v2: fix doc and memory leak > > > use xe_for_each_start > > > use standard genlmsg_iput (Jakub Kicinski) > > > > > > v3: add documentation to index > > > modify documentation to mention uAPI requirements (Rodrigo) > > > --- > > > Documentation/gpu/drm-ras.rst | 109 +++++++ > > > Documentation/gpu/index.rst | 1 + > > > Documentation/netlink/specs/drm_ras.yaml | 130 +++++++++ > > > drivers/gpu/drm/Kconfig | 9 + > > > drivers/gpu/drm/Makefile | 1 + > > > drivers/gpu/drm/drm_drv.c | 6 + > > > drivers/gpu/drm/drm_ras.c | 351 +++++++++++++++++++++++ > > > drivers/gpu/drm/drm_ras_genl_family.c | 42 +++ > > > drivers/gpu/drm/drm_ras_nl.c | 54 ++++ > > > include/drm/drm_ras.h | 76 +++++ > > > include/drm/drm_ras_genl_family.h | 17 ++ > > > include/drm/drm_ras_nl.h | 24 ++ > > > include/uapi/drm/drm_ras.h | 49 ++++ > > > 13 files changed, 869 insertions(+) > > > create mode 100644 Documentation/gpu/drm-ras.rst > > > create mode 100644 Documentation/netlink/specs/drm_ras.yaml > > > create mode 100644 drivers/gpu/drm/drm_ras.c > > > create mode 100644 drivers/gpu/drm/drm_ras_genl_family.c > > > create mode 100644 drivers/gpu/drm/drm_ras_nl.c > > > create mode 100644 include/drm/drm_ras.h > > > create mode 100644 include/drm/drm_ras_genl_family.h > > > create mode 100644 include/drm/drm_ras_nl.h > > > create mode 100644 include/uapi/drm/drm_ras.h > > > > > > diff --git a/Documentation/gpu/drm-ras.rst b/Documentation/gpu/drm-ras.rst > > > new file mode 100644 > > > index 000000000000..cec60cf5d17d > > > --- /dev/null > > > +++ b/Documentation/gpu/drm-ras.rst > > > @@ -0,0 +1,109 @@ > > > +.. SPDX-License-Identifier: GPL-2.0+ > > > + > > > +============================ > > > +DRM RAS over Generic Netlink > > > +============================ > > > + > > > +The DRM RAS (Reliability, Availability, Serviceability) interface provides a > > > +standardized way for GPU/accelerator drivers to expose error counters and > > > +other reliability nodes to user space via Generic Netlink. This allows > > > +diagnostic tools, monitoring daemons, or test infrastructure to query hardware > > > +health in a uniform way across different DRM drivers. > > > + > > > +Key Goals: > > > + > > > +* Provide a standardized RAS solution for GPU and accelerator drivers, enabling > > > + data center monitoring and reliability operations. > > > +* Implement a single drm-ras Generic Netlink family to meet modern Netlink YAML > > > + specifications and centralize all RAS-related communication in one namespace. > > > +* Support a basic error counter interface, addressing the immediate, essential > > > + monitoring needs. > > > +* Offer a flexible, future-proof interface that can be extended to support > > > + additional types of RAS data in the future. > > > +* Allow multiple nodes per driver, enabling drivers to register separate > > > + nodes for different IP blocks, sub-blocks, or other logical subdivisions > > > + as applicable. > > > + > > > +Nodes > > > +===== > > > + > > > +Nodes are logical abstractions representing an error source or block within > > > +the device. Currently, only error counter nodes is supported. > > > + > > > +Drivers are responsible for registering and unregistering nodes via the > > > +`drm_ras_node_register()` and `drm_ras_node_unregister()` APIs. > > > + > > > +Node Management > > > +------------------- > > > + > > > +.. kernel-doc:: drivers/gpu/drm/drm_ras.c > > > + :doc: DRM RAS Node Management > > > +.. kernel-doc:: drivers/gpu/drm/drm_ras.c > > > + :internal: > > > + > > > +Generic Netlink Usage > > > +===================== > > > + > > > +The interface is implemented as a Generic Netlink family named ``drm-ras``. > > > +User space tools can: > > > + > > > +* List registered nodes with the ``get-nodes`` command. > > > +* List all error counters in an node with the ``get-error-counters`` command. > > > +* Query error counters using the ``query-error-counter`` command. > > > + > > > +YAML-based Interface > > > +-------------------- > > > + > > > +The interface is described in a YAML specification: > > > + > > > +:ref:`Documentation/netlink/specs/drm_ras.yaml` > > > + > > > +This YAML is used to auto-generate user space bindings via > > > +``tools/net/ynl/pyynl/ynl_gen_c.py``, and drives the structure of netlink > > > +attributes and operations. > > > + > > > +Usage Notes > > > +----------- > > > + > > > +* User space must first enumerate nodes to obtain their IDs. > > > +* Node IDs or Node names can be used for all further queries, such as error counters. > > > +* Error counters can be queried by either the Error ID or Error name. > > > +* Query Parameters should be defined as part of the uAPI to ensure user interface stability. > > > +* The interface supports future extension by adding new node types and > > > + additional attributes. > > > + > > > +Example: List nodes using ynl > > > + > > > +.. code-block:: bash > > > + > > > + sudo ynl --family drm_ras --dump list-nodes > > > + [{'device-name': '0000:03:00.0', > > > + 'node-id': 0, > > > + 'node-name': 'correctable-errors', > > > + 'node-type': 'error-counter'}, > > > + {'device-name': '0000:03:00.0', > > > + 'node-id': 1, > > > + 'node-name': 'nonfatal-errors', > > > + 'node-type': 'error-counter'}, > > > + {'device-name': '0000:03:00.0', > > > + 'node-id': 2, > > > + 'node-name': 'fatal-errors', > > > + 'node-type': 'error-counter'}] > > > + > > > +Example: List all error counters using ynl > > > + > > > +.. code-block:: bash > > > + > > > + > > > + sudo ynl --family drm_ras --dump get-error-counters --json '{"node-id":1}' > > > + [{'error-id': 1, 'error-name': 'error_name_1', 'error-value': 0}, > > > + {'error-id': 2, 'error-name': 'error_name_2', 'error-value': 0}] > > > + > > > + > > > +Example: Query an error counter for a given node > > > + > > > +.. code-block:: bash > > > + > > > + sudo ynl --family drm_ras --do query-error-counter --json '{"node-id":2, "error-id":1}' > > > + {'error-id': 1, 'error-name': 'error_name_1', 'error-value': 0} > > > + > > > diff --git a/Documentation/gpu/index.rst b/Documentation/gpu/index.rst > > > index 7dcb15850afd..60c73fdcfeed 100644 > > > --- a/Documentation/gpu/index.rst > > > +++ b/Documentation/gpu/index.rst > > > @@ -9,6 +9,7 @@ GPU Driver Developer's Guide > > > drm-mm > > > drm-kms > > > drm-kms-helpers > > > + drm-ras > > > drm-uapi > > > drm-usage-stats > > > driver-uapi > > > diff --git a/Documentation/netlink/specs/drm_ras.yaml b/Documentation/netlink/specs/drm_ras.yaml > > > new file mode 100644 > > > index 000000000000..be0e379c5bc9 > > > --- /dev/null > > > +++ b/Documentation/netlink/specs/drm_ras.yaml > > > @@ -0,0 +1,130 @@ > > > +# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) > > > +--- > > > +name: drm-ras > > > +protocol: genetlink > > > +uapi-header: drm/drm_ras.h > > > + > > > +doc: >- > > > + DRM RAS (Reliability, Availability, Serviceability) over Generic Netlink. > > > + Provides a standardized mechanism for DRM drivers to register "nodes" > > > + representing hardware/software components capable of reporting error counters. > > > + Userspace tools can query the list of nodes or individual error counters > > > + via the Generic Netlink interface. > > > + > > > +definitions: > > > + - > > > + type: enum > > > + name: node-type > > > + value-start: 1 > > > + entries: [error-counter] > > > + doc: >- > > > + Type of the node. Currently, only error-counter nodes are > > > + supported, which expose reliability counters for a hardware/software > > > + component. > > > + > > > +attribute-sets: > > > + - > > > + name: node-attrs > > > + attributes: > > > + - > > > + name: node-id > > > + type: u32 > > > + doc: >- > > > + Unique identifier for the node. > > > + Assigned dynamically by the DRM RAS core upon registration. > > > + - > > > + name: device-name > > > + type: string > > > + doc: >- > > > + Device name chosen by the driver at registration. > > > + Can be a PCI BDF, UUID, or module name if unique. > > > + - > > > + name: node-name > > > + type: string > > > + doc: >- > > > + Node name chosen by the driver at registration. > > > + Can be an IP block name, or any name that identifies the > > > + RAS node inside the device. > > > + - > > > + name: node-type > > > + type: u32 > > > + doc: Type of this node, identifying its function. > > > + enum: node-type > > > + - > > > + name: error-counter-attrs > > > + attributes: > > > + - > > > + name: node-id > > > + type: u32 > > > + doc: Node ID targeted by this error counter operation. > > > + - > > > + name: error-id > > > + type: u32 > > > + doc: Unique identifier for a specific error counter within an node. > > > + - > > > + name: error-name > > > + type: string > > > + doc: Name of the error. > > > + - > > > + name: error-value > > > + type: u32 > > > + doc: Current value of the requested error counter. > > > + > > > +operations: > > > + list: > > > + - > > > + name: list-nodes > > > + doc: >- > > > + Retrieve the full list of currently registered DRM RAS nodes. > > > + Each node includes its dynamically assigned ID, name, and type. > > > + **Important:** User space must call this operation first to obtain > > > + the node IDs. These IDs are required for all subsequent > > > + operations on nodes, such as querying error counters. > > I am curious about security implications of this design. hmm... very good point you are raising here. This current design relies entirely in the CAP_NET_ADMIN. No driver would have the flexibility to choose anything differently. Please notice that the flag admin-perm is hardcoded in this yaml file. > If the complete > list of RAS nodes is visible for any process on the system (and one wants to > avoid requiring CAP_NET_ADMIN), there should be some way to enforce > permission checks when performing these operations if desired. Right now, there's no way that the driver would choose not avoid requiring CAP_NET_ADMIN... Only way would be the admin to give the cap_net_admin to the tool with: $ sudo setcap cap_net_admin+ep /bin/drm_ras_tool but not ideal and not granular anyway... > > For example, this might be implemented in the driver's definition of > callback functions like query_error_counter; some drivers may want to ensure > that the process can in fact open the file descriptor corresponding to the > queried device before serving a netlink request. Is it enough for a driver > to simply return -EPERM in this case? Any driver that doesnt wish to protect > its RAS nodes need not implement checks in their callbacks. Fair enough. If we want to give the option to the drivers, then we need: 1. to first remove all the admin-perm flags below and leave the driver to pick up their policy on when to return something or -EPERM. 2. Document this security responsibility and list a few possibilities. 3. In our Xe case here I believe the easiest option is to use something like: struct scm_creds *creds = NETLINK_CREDS(cb->skb); if (!gid_eq(creds->gid, GLOBAL_ROOT_GID)) return -EPERM or something like that?! perhaps drivers could implement some form of cookie or pre-authorization with ioctls or sysfs, and then store in the priv? Thoughts? Other options? > > I dont see any such permissions checks in your driver implementation which > is understandable given that it may not be necessary for your use cases. > However, this would be a concern for our driver if we were to adopt this > interface. yeap, this case was entirely with admin-perm, so not needed at all... But I see your point and this is really not giving any flexibility to other drivers. > > > > + attribute-set: node-attrs > > > + flags: [admin-perm] > > > + dump: > > > + reply: > > > + attributes: > > > + - node-id > > > + - device-name > > > + - node-name > > > + - node-type > > > + - > > > + name: get-error-counters > > > + doc: >- > > > + Retrieve the full list of error counters for a given node. > > > + The response include the id, the name, and even the current > > > + value of each counter. > > > + attribute-set: error-counter-attrs > > > + flags: [admin-perm] > > > + dump: > > > + request: > > > + attributes: > > > + - node-id > > > + reply: > > > + attributes: > > > + - error-id > > > + - error-name > > > + - error-value > > > + - > > > + name: query-error-counter > > > + doc: >- > > > + Query the information of a specific error counter for a given node. > > > + Users must provide the node ID and the error counter ID. > > > + The response contains the id, the name, and the current value > > > + of the counter. > > > + attribute-set: error-counter-attrs > > > + flags: [admin-perm] > > > + do: > > > + request: > > > + attributes: > > > + - node-id > > > + - error-id > > > + reply: > > > + attributes: > > > + - error-id > > > + - error-name > > > + - error-value > > > + > > > +kernel-family: > > > + headers: ["drm/drm_ras_nl.h"] > > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > > > index 7e6bc0b3a589..5cfb23b80441 100644 > > > --- a/drivers/gpu/drm/Kconfig > > > +++ b/drivers/gpu/drm/Kconfig > > > @@ -130,6 +130,15 @@ config DRM_PANIC_SCREEN_QR_VERSION > > > Smaller QR code are easier to read, but will contain less debugging > > > data. Default is 40. > > > +config DRM_RAS > > > + bool "DRM RAS support" > > > + depends on DRM > > > + help > > > + Enables the DRM RAS (Reliability, Availability and Serviceability) > > > + support for DRM drivers. This provides a Generic Netlink interface > > > + for error reporting and queries. > > > + If in doubt, say "N". > > > + > > > config DRM_DEBUG_DP_MST_TOPOLOGY_REFS > > > bool "Enable refcount backtrace history in the DP MST helpers" > > > depends on STACKTRACE_SUPPORT > > > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > > > index 4b3f3ad5058a..cd19573b2d9f 100644 > > > --- a/drivers/gpu/drm/Makefile > > > +++ b/drivers/gpu/drm/Makefile > > > @@ -95,6 +95,7 @@ drm-$(CONFIG_DRM_ACCEL) += ../../accel/drm_accel.o > > > drm-$(CONFIG_DRM_PANIC) += drm_panic.o > > > drm-$(CONFIG_DRM_DRAW) += drm_draw.o > > > drm-$(CONFIG_DRM_PANIC_SCREEN_QR_CODE) += drm_panic_qr.o > > > +drm-$(CONFIG_DRM_RAS) += drm_ras.o drm_ras_nl.o drm_ras_genl_family.o > > > obj-$(CONFIG_DRM) += drm.o > > > obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o > > > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c > > > index 2915118436ce..6b965c3d3307 100644 > > > --- a/drivers/gpu/drm/drm_drv.c > > > +++ b/drivers/gpu/drm/drm_drv.c > > > @@ -53,6 +53,7 @@ > > > #include > > > #include > > > #include > > > +#include > > > #include "drm_crtc_internal.h" > > > #include "drm_internal.h" > > > @@ -1223,6 +1224,7 @@ static const struct file_operations drm_stub_fops = { > > > static void drm_core_exit(void) > > > { > > > + drm_ras_genl_family_unregister(); > > > drm_privacy_screen_lookup_exit(); > > > drm_panic_exit(); > > > accel_core_exit(); > > > @@ -1261,6 +1263,10 @@ static int __init drm_core_init(void) > > > drm_privacy_screen_lookup_init(); > > > + ret = drm_ras_genl_family_register(); > > > + if (ret < 0) > > > + goto error; > > > + > > > drm_core_init_complete = true; > > > DRM_DEBUG("Initialized\n"); > > > diff --git a/drivers/gpu/drm/drm_ras.c b/drivers/gpu/drm/drm_ras.c > > > new file mode 100644 > > > index 000000000000..32f3897ce580 > > > --- /dev/null > > > +++ b/drivers/gpu/drm/drm_ras.c > > > @@ -0,0 +1,351 @@ > > > +// SPDX-License-Identifier: MIT > > > +/* > > > + * Copyright © 2025 Intel Corporation > > > + */ > > > + > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > + > > > +#include > > > + > > > +/** > > > + * DOC: DRM RAS Node Management > > > + * > > > + * This module provides the infrastructure to manage RAS (Reliability, > > > + * Availability, and Serviceability) nodes for DRM drivers. Each > > > + * DRM driver may register one or more RAS nodes, which represent > > > + * logical components capable of reporting error counters and other > > > + * reliability metrics. > > > + * > > > + * The nodes are stored in a global xarray `drm_ras_xa` to allow > > > + * efficient lookup by ID. Nodes can be registered or unregistered > > > + * dynamically at runtime. > > > + * > > > + * A Generic Netlink family `drm_ras` exposes two main operations to > > > + * userspace: > > Nit: Three main operations. ops, my bad, sorry > > > > + * > > > + * 1. LIST_NODES: Dump all currently registered RAS nodes. > > > + * The user receives an array of node IDs, names, and types. > > > + * > > > + * 2. GET_ERROR_COUNTERS: Dump all error counters of a given node. > > > + * The user receives an array of error IDs, names, and current value. > > > + * > > > + * 3. QUERY_ERROR_COUNTER: Query a specific error counter for a given node. > > > + * Userspace must provide the node ID and the counter ID, and > > > + * receives the ID, the error name, and its current value. > > > + * > > > + * Node registration: > > > + * - drm_ras_node_register(): Registers a new node and assigns > > > + * it a unique ID in the xarray. > > > + * - drm_ras_node_unregister(): Removes a previously registered > > > + * node from the xarray. > > > + * > > > + * Node type: > > > + * - ERROR_COUNTER: > > > + * + Currently, only error counters are supported. > > > + * + The driver must implement the query_error_counter() callback to provide > > > + * the name and the value of the error counter. > > > + * + The driver must provide a error_counter_range.last value informing the > > > + * last valid error ID. > > > + * + The driver can provide a error_counter_range.first value informing the > > > + * frst valid error ID. > > > + * + The error counters in the driver doesn't need to be contiguous, but the > > > + * driver must return -ENOENT to the query_error_counter as an indication > > > + * that the ID should be skipped and not listed in the netlink API. > > > + * > > > + * Netlink handlers: > > > + * - drm_ras_nl_list_nodes_dumpit(): Implements the LIST_NODES > > > + * operation, iterating over the xarray. > > > + * - drm_ras_nl_get_error_counters_dumpit(): Implements the GET_ERROR_COUNTERS > > > + * operation, iterating over the know valid error_counter_range. > > > + * - drm_ras_nl_query_error_counter_doit(): Implements the QUERY_ERROR_COUNTER > > > + * operation, fetching a counter value from a specific node. > > > + */ > > > + > > > +static DEFINE_XARRAY_ALLOC(drm_ras_xa); > > > + > > > +/* > > > + * The netlink callback context carries dump state across multiple dumpit calls > > > + */ > > > +struct drm_ras_ctx { > > > + /* Which xarray id to restart the dump from */ > > > + unsigned long restart; > > > +}; > > > + > > > +/** > > > + * drm_ras_nl_list_nodes_dumpit() - Dump all registered RAS nodes > > > + * @skb: Netlink message buffer > > > + * @cb: Callback context for multi-part dumps > > > + * > > > + * Iterates over all registered RAS nodes in the global xarray and appends > > > + * their attributes (ID, name, type) to the given netlink message buffer. > > > + * Uses @cb->ctx to track progress in case the message buffer fills up, allowing > > > + * multi-part dump support. On buffer overflow, updates the context to resume > > > + * from the last node on the next invocation. > > > + * > > > + * Return: 0 if all nodes fit in @skb, number of bytes added to @skb if > > > + * the buffer filled up (requires multi-part continuation), or > > > + * a negative error code on failure. > > > + */ > > > +int drm_ras_nl_list_nodes_dumpit(struct sk_buff *skb, > > > + struct netlink_callback *cb) > > > +{ > > > + const struct genl_info *info = genl_info_dump(cb); > > > + struct drm_ras_ctx *ctx = (void *)cb->ctx; > > > + struct drm_ras_node *node; > > > + struct nlattr *hdr; > > > + unsigned long id; > > > + int ret; > > > + > > > + xa_for_each_start(&drm_ras_xa, id, node, ctx->restart) { > > > + hdr = genlmsg_iput(skb, info); > > > + if (!hdr) { > > > + ret = -EMSGSIZE; > > > + break; > > > + } > > > + > > > + ret = nla_put_u32(skb, DRM_RAS_A_NODE_ATTRS_NODE_ID, node->id); > > > + if (ret) { > > > + genlmsg_cancel(skb, hdr); > > > + break; > > > + } > > > + > > > + ret = nla_put_string(skb, DRM_RAS_A_NODE_ATTRS_DEVICE_NAME, > > > + node->device_name); > > > + if (ret) { > > > + genlmsg_cancel(skb, hdr); > > > + break; > > > + } > > > + > > > + ret = nla_put_string(skb, DRM_RAS_A_NODE_ATTRS_NODE_NAME, > > > + node->node_name); > > > + if (ret) { > > > + genlmsg_cancel(skb, hdr); > > > + break; > > > + } > > > + > > > + ret = nla_put_u32(skb, DRM_RAS_A_NODE_ATTRS_NODE_TYPE, > > > + node->type); > > > + if (ret) { > > > + genlmsg_cancel(skb, hdr); > > > + break; > > > + } > > > + > > > + genlmsg_end(skb, hdr); > > > + } > > > + > > > + if (ret == -EMSGSIZE) > > > + ctx->restart = id; > > > > Jakub had mentioned that we don't need this special handling > > of the -EMSGSIZE, but then I'm not sure what to use in the > > xa_for_each_start, so > > > > Cc: Jakub Kicinski > > > > to ensure that we are in the right path here. > > > > Riana, thank you so much for picking up this and addressing all > > the comments. Patch looks good to me. > > > > Thanks, > > Rodrigo. > > > > > + > > > + return ret; > > > +} > > > + > > > +static int get_node_error_counter(u32 node_id, u32 error_id, > > > + const char **name, u32 *value) > > > +{ > > > + struct drm_ras_node *node; > > > + > > > + node = xa_load(&drm_ras_xa, node_id); > > > + if (!node || !node->query_error_counter) > > > + return -ENOENT; > > > + > > > + if (error_id < node->error_counter_range.first || > > > + error_id > node->error_counter_range.last) > > > + return -EINVAL; > > > + > > > + return node->query_error_counter(node, error_id, name, value); > > > +} > > Regarding the permission check, node->query_error_counter could be > implemented to return -EPERM in this case by checking driver specified > fields in node->priv. Thoughts? Yeap, please let me know your thoughts above on how drivers could check and then return here and let's come to a flexible but secure design. > > > > + > > > +static int msg_reply_value(struct sk_buff *msg, u32 error_id, > > > + const char *error_name, u32 value) > > > +{ > > > + int ret; > > > + > > > + ret = nla_put_u32(msg, DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID, error_id); > > > + if (ret) > > > + return ret; > > > + > > > + ret = nla_put_string(msg, DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_NAME, > > > + error_name); > > > + if (ret) > > > + return ret; > > > + > > > + return nla_put_u32(msg, DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_VALUE, > > > + value); > > > +} > > > + > > > +static int doit_reply_value(struct genl_info *info, u32 node_id, > > > + u32 error_id) > > > +{ > > > + struct sk_buff *msg; > > > + struct nlattr *hdr; > > > + const char *error_name; > > > + u32 value; > > > + int ret; > > > + > > > + msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL); > > > + if (!msg) > > > + return -ENOMEM; > > > + > > > + hdr = genlmsg_iput(msg, info); > > > + if (!hdr) { > > > + nlmsg_free(msg); > > > + return -EMSGSIZE; > > > + } > > > + > > > + ret = get_node_error_counter(node_id, error_id, > > > + &error_name, &value); > > > + if (ret) > > > + return ret; > > > + > > > + ret = msg_reply_value(msg, error_id, error_name, value); > > > + if (ret) { > > > + genlmsg_cancel(msg, hdr); > > > + nlmsg_free(msg); > > > + return ret; > > > + } > > > + > > > + genlmsg_end(msg, hdr); > > > + > > > + return genlmsg_reply(msg, info); > > > +} > > > + > > > +/** > > > + * drm_ras_nl_get_error_counters_dumpit() - Dump all Error Counters > > > + * @skb: Netlink message buffer > > > + * @cb: Callback context for multi-part dumps > > > + * > > > + * Iterates over all error counters in a given Node and appends > > > + * their attributes (ID, name, value) to the given netlink message buffer. > > > + * Uses @cb->ctx to track progress in case the message buffer fills up, allowing > > > + * multi-part dump support. On buffer overflow, updates the context to resume > > > + * from the last node on the next invocation. > > > + * > > > + * Return: 0 if all errors fit in @skb, number of bytes added to @skb if > > > + * the buffer filled up (requires multi-part continuation), or > > > + * a negative error code on failure. > > > + */ > > > +int drm_ras_nl_get_error_counters_dumpit(struct sk_buff *skb, > > > + struct netlink_callback *cb) > > > +{ > > > + const struct genl_info *info = genl_info_dump(cb); > > > + struct drm_ras_ctx *ctx = (void *)cb->ctx; > > > + struct drm_ras_node *node; > > > + struct nlattr *hdr; > > > + const char *error_name; > > > + u32 node_id, error_id, value; > > > + int ret; > > > + > > > + if (!info->attrs || !info->attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID]) > > > + return -EINVAL; > > > + > > > + node_id = nla_get_u32(info->attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID]); > > > + > > > + node = xa_load(&drm_ras_xa, node_id); > > > + if (!node) > > > + return -ENOENT; > > > + > > > + for (error_id = max(node->error_counter_range.first, ctx->restart); > > > + error_id <= node->error_counter_range.last; > > > + error_id++) { > > > + ret = get_node_error_counter(node_id, error_id, > > > + &error_name, &value); > > > + /* > > > + * For non-contiguous range, driver return -ENOENT as indication > > > + * to skip this ID when listing all errors. > > > + */ > > > + if (ret == -ENOENT) > > > + continue; > > > + if (ret) > > > + return ret; > > > + > > > + hdr = genlmsg_iput(skb, info); > > > + > > > + if (!hdr) { > > > + ret = -EMSGSIZE; > > > + break; > > > + } > > > + > > > + ret = msg_reply_value(skb, error_id, error_name, value); > > > + if (ret) { > > > + genlmsg_cancel(skb, hdr); > > > + break; > > > + } > > > + > > > + genlmsg_end(skb, hdr); > > > + } > > > + > > > + if (ret == -EMSGSIZE) > > > + ctx->restart = error_id; > > > + > > > + return ret; > > > +} > > > + > > > +/** > > > + * drm_ras_nl_query_error_counter_doit() - Query an error counter of an node > > > + * @skb: Netlink message buffer > > > + * @info: Generic Netlink info containing attributes of the request > > > + * > > > + * Extracts the node ID and error ID from the netlink attributes and > > > + * retrieves the current value of the corresponding error counter. Sends the > > > + * result back to the requesting user via the standard Genl reply. > > > + * > > > + * Return: 0 on success, or negative errno on failure. > > > + */ > > > +int drm_ras_nl_query_error_counter_doit(struct sk_buff *skb, > > > + struct genl_info *info) > > > +{ > > > + u32 node_id, error_id; > > > + > > > + if (!info->attrs || > > > + !info->attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID] || > > > + !info->attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID]) > > > + return -EINVAL; > > > + > > > + node_id = nla_get_u32(info->attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID]); > > > + error_id = nla_get_u32(info->attrs[DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID]); > > > + > > > + return doit_reply_value(info, node_id, error_id); > > > +} > > > + > > > +/** > > > + * drm_ras_node_register() - Register a new RAS node > > > + * @node: Node structure to register > > > + * > > > + * Adds the given RAS node to the global node xarray and assigns it > > > + * a unique ID. Both @node->name and @node->type must be valid. > > > + * > > > + * Return: 0 on success, or negative errno on failure: > > > + */ > > > +int drm_ras_node_register(struct drm_ras_node *node) > > > +{ > > > + if (!node->device_name || !node->node_name) > > > + return -EINVAL; > > > + > > > + /* Currently, only Error Counter Endpoinnts are supported */ > > > + if (node->type != DRM_RAS_NODE_TYPE_ERROR_COUNTER) > > > + return -EINVAL; > > > + > > > + /* Mandatorty entries for Error Counter Node */ > > > + if (node->type == DRM_RAS_NODE_TYPE_ERROR_COUNTER && > > > + (!node->error_counter_range.last || !node->query_error_counter)) > > > + return -EINVAL; > > > + > > > + return xa_alloc(&drm_ras_xa, &node->id, node, xa_limit_32b, GFP_KERNEL); > > > +} > > > +EXPORT_SYMBOL(drm_ras_node_register); > > > + > > > +/** > > > + * drm_ras_node_unregister() - Unregister a previously registered node > > > + * @node: Node structure to unregister > > > + * > > > + * Removes the given node from the global node xarray using its ID. > > > + */ > > > +void drm_ras_node_unregister(struct drm_ras_node *node) > > > +{ > > > + xa_erase(&drm_ras_xa, node->id); > > > +} > > > +EXPORT_SYMBOL(drm_ras_node_unregister); > > > diff --git a/drivers/gpu/drm/drm_ras_genl_family.c b/drivers/gpu/drm/drm_ras_genl_family.c > > > new file mode 100644 > > > index 000000000000..2d818b8c3808 > > > --- /dev/null > > > +++ b/drivers/gpu/drm/drm_ras_genl_family.c > > > @@ -0,0 +1,42 @@ > > > +// SPDX-License-Identifier: MIT > > > +/* > > > + * Copyright © 2025 Intel Corporation > > > + */ > > > + > > > +#include > > > +#include > > > + > > > +/* Track family registration so the drm_exit can be called at any time */ > > > +static bool registered; > > > + > > > +/** > > > + * drm_ras_genl_family_register() - Register drm-ras genl family > > > + * > > > + * Only to be called one at drm_drv_init() > > > + */ > > > +int drm_ras_genl_family_register(void) > > > +{ > > > + int ret; > > > + > > > + registered = false; > > > + > > > + ret = genl_register_family(&drm_ras_nl_family); > > > + if (ret) > > > + return ret; > > > + > > > + registered = true; > > > + return 0; > > > +} > > > + > > > +/** > > > + * drm_ras_genl_family_unregister() - Unregister drm-ras genl family > > > + * > > > + * To be called one at drm_drv_exit() at any moment, but only once. > > > + */ > > > +void drm_ras_genl_family_unregister(void) > > > +{ > > > + if (registered) { > > > + genl_unregister_family(&drm_ras_nl_family); > > > + registered = false; > > > + } > > > +} > > > diff --git a/drivers/gpu/drm/drm_ras_nl.c b/drivers/gpu/drm/drm_ras_nl.c > > > new file mode 100644 > > > index 000000000000..fcd1392410e4 > > > --- /dev/null > > > +++ b/drivers/gpu/drm/drm_ras_nl.c > > > @@ -0,0 +1,54 @@ > > > +// SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) > > > +/* Do not edit directly, auto-generated from: */ > > > +/* Documentation/netlink/specs/drm_ras.yaml */ > > > +/* YNL-GEN kernel source */ > > > + > > > +#include > > > +#include > > > + > > > +#include > > > +#include > > > + > > > +/* DRM_RAS_CMD_GET_ERROR_COUNTERS - dump */ > > > +static const struct nla_policy drm_ras_get_error_counters_nl_policy[DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID + 1] = { > > > + [DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID] = { .type = NLA_U32, }, > > > +}; > > > + > > > +/* DRM_RAS_CMD_QUERY_ERROR_COUNTER - do */ > > > +static const struct nla_policy drm_ras_query_error_counter_nl_policy[DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID + 1] = { > > > + [DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID] = { .type = NLA_U32, }, > > > + [DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID] = { .type = NLA_U32, }, > > > +}; > > > + > > > +/* Ops table for drm_ras */ > > > +static const struct genl_split_ops drm_ras_nl_ops[] = { > > > + { > > > + .cmd = DRM_RAS_CMD_LIST_NODES, > > > + .dumpit = drm_ras_nl_list_nodes_dumpit, > > > + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, > > > + }, > > > + { > > > + .cmd = DRM_RAS_CMD_GET_ERROR_COUNTERS, > > > + .dumpit = drm_ras_nl_get_error_counters_dumpit, > > > + .policy = drm_ras_get_error_counters_nl_policy, > > > + .maxattr = DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID, > > > + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DUMP, > > > + }, > > > + { > > > + .cmd = DRM_RAS_CMD_QUERY_ERROR_COUNTER, > > > + .doit = drm_ras_nl_query_error_counter_doit, > > > + .policy = drm_ras_query_error_counter_nl_policy, > > > + .maxattr = DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID, > > > + .flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO, > > > + }, > > > +}; > > > + > > > +struct genl_family drm_ras_nl_family __ro_after_init = { > > > + .name = DRM_RAS_FAMILY_NAME, > > > + .version = DRM_RAS_FAMILY_VERSION, > > > + .netnsok = true, > > > + .parallel_ops = true, > > > + .module = THIS_MODULE, > > > + .split_ops = drm_ras_nl_ops, > > > + .n_split_ops = ARRAY_SIZE(drm_ras_nl_ops), > > > +}; > > > diff --git a/include/drm/drm_ras.h b/include/drm/drm_ras.h > > > new file mode 100644 > > > index 000000000000..bba47a282ef8 > > > --- /dev/null > > > +++ b/include/drm/drm_ras.h > > > @@ -0,0 +1,76 @@ > > > +/* SPDX-License-Identifier: MIT */ > > > +/* > > > + * Copyright © 2025 Intel Corporation > > > + */ > > > + > > > +#ifndef __DRM_RAS_H__ > > > +#define __DRM_RAS_H__ > > > + > > > +#include "drm_ras_nl.h" > > > + > > > +/** > > > + * struct drm_ras_node - A DRM RAS Node > > > + */ > > > +struct drm_ras_node { > > > + /** @id: Unique identifier for the node. Dynamically assigned. */ > > > + u32 id; > > > + /** > > > + * @device_name: Human-readable name of the device. Given by the driver. > > > + */ > > > + const char *device_name; > > > + /** @node_name: Human-readable name of the node. Given by the driver. */ > > > + const char *node_name; > > > + /** @type: Type of the node (enum drm_ras_node_type). */ > > > + enum drm_ras_node_type type; > > > + > > > + /* Error-Counter Related Callback and Variables */ > > > + > > > + /** @error_counter_range: Range of valid Error IDs for this node. */ > > > + struct { > > > + /** @first: First valid Error ID. */ > > > + u32 first; > > > + /** @last: Last valid Error ID. Mandatory entry. */ > > > + u32 last; > > > + } error_counter_range; > > > + > > > + /** > > > + * @query_error_counter: > > > + * > > > + * This callback is used by drm-ras to query a specific error counter. > > > + * counters supported by this node. Used for input check and to > > > + * iterate in all counters. > > > + * > > > + * Driver should expect query_error_counters() to be called with > > > + * error_id from `error_counter_range.first` to > > > + * `error_counter_range.last`. > > > + * > > > + * The @query_error_counter is a mandatory callback for > > > + * error_counter_node. > > > + * > > > + * Returns: 0 on success, > > > + * -ENOENT when error_id is not supported as an indication that > > > + * drm_ras should silently skip this entry. Used for > > > + * supporting non-contiguous error ranges. > > > + * Driver is responsible for maintaining the list of > > > + * supported error IDs in the range of first to last. > > > + * Other negative values on errors that should terminate the > > > + * netlink query. > > > + */ > > > + int (*query_error_counter)(struct drm_ras_node *ep, u32 error_id, > > > + const char **name, u32 *val); > > > + > > > + /** @priv: Driver private data */ > > > + void *priv; > > > +}; > > > + > > If new node types are frequently added, this struct may contain many > unused fields. It seems like the necessary members for any given node > type are: id, device_name, node_name, type, and priv. However, since > this functionality is designed specifically for RAS, I think its ok. Yeap, that was the thought. Thank you so much for the review and thoughts here, Rodrigo. > > > > +struct drm_device; > > > + > > > +#if IS_ENABLED(CONFIG_DRM_RAS) > > > +int drm_ras_node_register(struct drm_ras_node *ep); > > > +void drm_ras_node_unregister(struct drm_ras_node *ep); > > > +#else > > > +static inline int drm_ras_node_register(struct drm_ras_node *ep) { return 0; } > > > +static inline void drm_ras_node_unregister(struct drm_ras_node *ep) { } > > > +#endif > > > + > > > +#endif > > > diff --git a/include/drm/drm_ras_genl_family.h b/include/drm/drm_ras_genl_family.h > > > new file mode 100644 > > > index 000000000000..5931b53429f1 > > > --- /dev/null > > > +++ b/include/drm/drm_ras_genl_family.h > > > @@ -0,0 +1,17 @@ > > > +/* SPDX-License-Identifier: MIT */ > > > +/* > > > + * Copyright © 2025 Intel Corporation > > > + */ > > > + > > > +#ifndef __DRM_RAS_GENL_FAMILY_H__ > > > +#define __DRM_RAS_GENL_FAMILY_H__ > > > + > > > +#if IS_ENABLED(CONFIG_DRM_RAS) > > > +int drm_ras_genl_family_register(void); > > > +void drm_ras_genl_family_unregister(void); > > > +#else > > > +static inline int drm_ras_genl_family_register(void) { return 0; } > > > +static inline void drm_ras_genl_family_unregister(void) { } > > > +#endif > > > + > > > +#endif > > > diff --git a/include/drm/drm_ras_nl.h b/include/drm/drm_ras_nl.h > > > new file mode 100644 > > > index 000000000000..9613b7d9ffdb > > > --- /dev/null > > > +++ b/include/drm/drm_ras_nl.h > > > @@ -0,0 +1,24 @@ > > > +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ > > > +/* Do not edit directly, auto-generated from: */ > > > +/* Documentation/netlink/specs/drm_ras.yaml */ > > > +/* YNL-GEN kernel header */ > > > + > > > +#ifndef _LINUX_DRM_RAS_GEN_H > > > +#define _LINUX_DRM_RAS_GEN_H > > > + > > > +#include > > > +#include > > > + > > > +#include > > > +#include > > > + > > > +int drm_ras_nl_list_nodes_dumpit(struct sk_buff *skb, > > > + struct netlink_callback *cb); > > > +int drm_ras_nl_get_error_counters_dumpit(struct sk_buff *skb, > > > + struct netlink_callback *cb); > > > +int drm_ras_nl_query_error_counter_doit(struct sk_buff *skb, > > > + struct genl_info *info); > > > + > > > +extern struct genl_family drm_ras_nl_family; > > > + > > > +#endif /* _LINUX_DRM_RAS_GEN_H */ > > > diff --git a/include/uapi/drm/drm_ras.h b/include/uapi/drm/drm_ras.h > > > new file mode 100644 > > > index 000000000000..3415ba345ac8 > > > --- /dev/null > > > +++ b/include/uapi/drm/drm_ras.h > > > @@ -0,0 +1,49 @@ > > > +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */ > > > +/* Do not edit directly, auto-generated from: */ > > > +/* Documentation/netlink/specs/drm_ras.yaml */ > > > +/* YNL-GEN uapi header */ > > > + > > > +#ifndef _UAPI_LINUX_DRM_RAS_H > > > +#define _UAPI_LINUX_DRM_RAS_H > > > + > > > +#define DRM_RAS_FAMILY_NAME "drm-ras" > > > +#define DRM_RAS_FAMILY_VERSION 1 > > > + > > > +/* > > > + * Type of the node. Currently, only error-counter nodes are supported, which > > > + * expose reliability counters for a hardware/software component. > > > + */ > > > +enum drm_ras_node_type { > > > + DRM_RAS_NODE_TYPE_ERROR_COUNTER = 1, > > > +}; > > > + > > > +enum { > > > + DRM_RAS_A_NODE_ATTRS_NODE_ID = 1, > > > + DRM_RAS_A_NODE_ATTRS_DEVICE_NAME, > > > + DRM_RAS_A_NODE_ATTRS_NODE_NAME, > > > + DRM_RAS_A_NODE_ATTRS_NODE_TYPE, > > > + > > > + __DRM_RAS_A_NODE_ATTRS_MAX, > > > + DRM_RAS_A_NODE_ATTRS_MAX = (__DRM_RAS_A_NODE_ATTRS_MAX - 1) > > > +}; > > > + > > > +enum { > > > + DRM_RAS_A_ERROR_COUNTER_ATTRS_NODE_ID = 1, > > > + DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_ID, > > > + DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_NAME, > > > + DRM_RAS_A_ERROR_COUNTER_ATTRS_ERROR_VALUE, > > > + > > > + __DRM_RAS_A_ERROR_COUNTER_ATTRS_MAX, > > > + DRM_RAS_A_ERROR_COUNTER_ATTRS_MAX = (__DRM_RAS_A_ERROR_COUNTER_ATTRS_MAX - 1) > > > +}; > > > + > > > +enum { > > > + DRM_RAS_CMD_LIST_NODES = 1, > > > + DRM_RAS_CMD_GET_ERROR_COUNTERS, > > > + DRM_RAS_CMD_QUERY_ERROR_COUNTER, > > > + > > > + __DRM_RAS_CMD_MAX, > > > + DRM_RAS_CMD_MAX = (__DRM_RAS_CMD_MAX - 1) > > > +}; > > > + > > > +#endif /* _UAPI_LINUX_DRM_RAS_H */ > > > -- > > > 2.47.1 > > > > > Thanks, > > Zack >