RE: [PATCH v3 4/4] drm/xe/sysctrl: Add RAS error injection debugfs interface

> -----Original Message-----
> From: Vijay, Anoop C <[email protected]>
> Sent: Friday, August 7, 2026 8:26 PM
> To: [email protected]
> Cc: Nerlige Ramappa, Umesh <[email protected]>; Nilawar,
> Badal <[email protected]>; Vivi, Rodrigo <[email protected]>;
> Iddamsetty, Aravind <[email protected]>; Tauro, Riana
> <[email protected]>; Gupta, Anshuman <[email protected]>;
> Roper, Matthew D <[email protected]>; Ruhl, Michael J
> <[email protected]>; Luse, Paul E <[email protected]>; V,
> Mohamed Mansoor <[email protected]>; Nasim, Kam
> <[email protected]>; Vijay, Anoop C <[email protected]>
> Subject: [PATCH v3 4/4] drm/xe/sysctrl: Add RAS error injection debugfs
> interface
> 
> From: Anoop Vijay <[email protected]>
> 
> Add debugfs interface for exercising System Controller's RAS error injection
> command, used to validate RAS error detection and recovery paths.
> 
> Command details:
> - Group ID: 0x02 (diag group)
> - Command ID: 0x7E (XE_SYSCTRL_CMD_DIAG_RAS_ERR_INJECT)
> - Usage: echo "<ras_block_id> <ras_sub_block_id> <err_type> [params]" \
>              > /sys/kernel/debug/dri/0/sc/ras_error_inject
>          cat /sys/kernel/debug/dri/0/sc/ras_error_inject
> 
> This command requires the diag application to have completed firmware
> boot and initialization (late-bind loaded); writes are rejected with -ENODEV
> until xe_sysctrl_is_diag_fw_ready() reports the diag firmware as ready.
> 
> Signed-off-by: Anoop Vijay <[email protected]>
> ---
>  drivers/gpu/drm/xe/xe_sysctrl_debugfs.c       | 123 ++++++++++++++++++
>  drivers/gpu/drm/xe/xe_sysctrl_mailbox_types.h |  31 +++++
>  drivers/gpu/drm/xe/xe_sysctrl_types.h         |   3 +
>  3 files changed, 157 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_sysctrl_debugfs.c
> b/drivers/gpu/drm/xe/xe_sysctrl_debugfs.c
> index 2144d9d43fba..7b8846d739cb 100644
> --- a/drivers/gpu/drm/xe/xe_sysctrl_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_sysctrl_debugfs.c
> @@ -10,6 +10,7 @@
>  #include <linux/seq_file.h>
>  #include <linux/slab.h>
>  #include <linux/string.h>
> +#include <linux/string_choices.h>
>  #include <linux/uaccess.h>
> 
>  #include "xe_device.h"
> @@ -122,6 +123,124 @@ static const struct file_operations
> xe_sysctrl_loopback_fops = {
>  	.release = single_release,
>  };
> 
> +static ssize_t xe_sysctrl_ras_error_inject_write(struct file *file, const char
> __user *ubuf,
> +						 size_t len, loff_t *offp)
> +{
> +	char *kbuf __free(kfree) = NULL;
> +	struct seq_file *m = file->private_data;
> +	struct xe_sysctrl_debugfs_entry *entry = m->private;
> +	struct xe_device *xe = sc_to_xe(entry->sc);
> +	struct xe_sysctrl_diag_ras_err_inj_req req = {};
> +	struct xe_sysctrl_mailbox_command cmd = {};
> +	u8 resp_hdr_only[sizeof(u32)];
> +	unsigned int nfields = 0;
> +	char *token, *tmp;
> +	unsigned long val;
> +	size_t out_len = 0;
> +
> +	if (!xe_sysctrl_is_diag_fw_ready(xe)) {
> +		xe_err(xe, "sysctrl: diag firmware not ready, cannot inject RAS
> error\n");
Wild thought, 
How it would be register the debugfs only if  diag firmware is loaded ?
That way nobody will be having access to these debugfs ? 

Thanks,
Anshuman.

> +		return -ENODEV;
> +	}
> +
> +	if (len == 0 || len >= PAGE_SIZE)
> +		return -EINVAL;
> +
> +	kbuf = kmalloc(len + 1, GFP_KERNEL);
> +	if (!kbuf)
> +		return -ENOMEM;
> +
> +	if (copy_from_user(kbuf, ubuf, len))
> +		return -EFAULT;
> +	kbuf[len] = '\0';
> +
> +	tmp = kbuf;
> +	while ((token = strsep(&tmp, " \t\n")) != NULL) {
> +		if (*token == '\0')
> +			continue;
> +
> +		if (kstrtoul(token, 0, &val))
> +			goto inval;
> +
> +		switch (nfields) {
> +		case 0:
> +			if (val > U16_MAX)
> +				goto inval;
> +			req.ras_block_id = val;
> +			break;
> +		case 1:
> +			if (val > U16_MAX)
> +				goto inval;
> +			req.ras_sub_block_id = val;
> +			break;
> +		case 2:
> +			if (val > U16_MAX)
> +				goto inval;
> +			req.err_type = val;
> +			break;
> +		case 3:
> +			if (val > U32_MAX)
> +				goto inval;
> +			req.params = val;
> +			break;
> +		default:
> +			xe_err(xe, "sysctrl: too many ras_error_inject
> arguments\n");
> +			return -EINVAL;
> +		}
> +		nfields++;
> +	}
> +
> +	if (nfields < 3) {
> +		xe_err(xe,
> +		       "sysctrl: usage: <ras_block_id> <ras_sub_block_id>
> <err_type> [params]\n");
> +		return -EINVAL;
> +	}
> +
> +	xe_sysctrl_create_command(&cmd, entry->group, entry->command,
> +				  &req, sizeof(req), resp_hdr_only,
> +				  sizeof(resp_hdr_only));
> +
> +	guard(xe_pm_runtime)(xe);
> +	entry->status = xe_sysctrl_send_command(entry->sc, &cmd,
> &out_len);
> +
> +	return entry->status ? entry->status : len;
> +
> +inval:
> +	xe_err(xe, "sysctrl: invalid ras_error_inject token '%s'\n", token);
> +	return -EINVAL;
> +}
> +
> +static int xe_sysctrl_ras_error_inject_show(struct seq_file *m, void
> +*data) {
> +	struct xe_sysctrl_debugfs_entry *entry = m->private;
> +	struct xe_device *xe = sc_to_xe(entry->sc);
> +
> +	seq_printf(m, "Command: group=0x%02x cmd=0x%02x\n", entry-
> >group, entry->command);
> +	seq_printf(m, "Diag firmware ready: %s\n",
> +		   str_yes_no(xe_sysctrl_is_diag_fw_ready(xe)));
> +	seq_printf(m, "Status: %d (%s)\n", entry->status, entry->status ?
> +"FAILED" : "SUCCESS");
> +
> +	seq_puts(m, "\nUsage:\n");
> +	seq_puts(m, "  echo \"<ras_block_id> <ras_sub_block_id>
> <err_type> [params]\" > ras_error_inject\n");
> +	seq_puts(m, "  cat ras_error_inject\n");
> +
> +	return 0;
> +}
> +
> +static int xe_sysctrl_ras_error_inject_open(struct inode *inode, struct
> +file *file) {
> +	return single_open(file, xe_sysctrl_ras_error_inject_show,
> +inode->i_private); }
> +
> +static const struct file_operations xe_sysctrl_ras_error_inject_fops = {
> +	.owner = THIS_MODULE,
> +	.open = xe_sysctrl_ras_error_inject_open,
> +	.read = seq_read,
> +	.write = xe_sysctrl_ras_error_inject_write,
> +	.llseek = seq_lseek,
> +	.release = single_release,
> +};
> +
>  static void xe_sysctrl_register_entry(struct dentry *root, struct
> xe_sysctrl_debugfs_entry *entry,
>  				      struct xe_sysctrl *sc, const char *name,
>  				      u8 group, u8 command,
> @@ -154,4 +273,8 @@ void xe_sysctrl_debugfs_register(struct xe_sysctrl
> *sc, struct dentry *parent)
>  	xe_sysctrl_register_entry(root, &sc->debugfs.loopback, sc,
> "loopback",
>  				  XE_SYSCTRL_GROUP_CORE,
> XE_SYSCTRL_CMD_LOOPBACK,
>  				  &xe_sysctrl_loopback_fops);
> +
> +	xe_sysctrl_register_entry(root, &sc->debugfs.ras_error_inject, sc,
> "ras_error_inject",
> +				  XE_SYSCTRL_GROUP_DIAG,
> XE_SYSCTRL_CMD_DIAG_RAS_ERR_INJECT,
> +				  &xe_sysctrl_ras_error_inject_fops);
>  }
> diff --git a/drivers/gpu/drm/xe/xe_sysctrl_mailbox_types.h
> b/drivers/gpu/drm/xe/xe_sysctrl_mailbox_types.h
> index ed80fe63e1c4..43ae0049b316 100644
> --- a/drivers/gpu/drm/xe/xe_sysctrl_mailbox_types.h
> +++ b/drivers/gpu/drm/xe/xe_sysctrl_mailbox_types.h
> @@ -14,10 +14,12 @@
>   * enum xe_sysctrl_group - System Controller command groups
>   *
>   * @XE_SYSCTRL_GROUP_GFSP: GFSP group
> + * @XE_SYSCTRL_GROUP_DIAG: Diag group
>   * @XE_SYSCTRL_GROUP_CORE: Core group
>   */
>  enum xe_sysctrl_group {
>  	XE_SYSCTRL_GROUP_GFSP			= 0x01,
> +	XE_SYSCTRL_GROUP_DIAG			= 0x02,
>  	XE_SYSCTRL_GROUP_CORE			= 0xFF,
>  };
> 
> @@ -51,6 +53,35 @@ enum xe_sysctrl_core_cmd {
>  	XE_SYSCTRL_CMD_GET_APP_STATUS_BY_ID		= 0x05,
>  };
> 
> +/**
> + * enum xe_sysctrl_diag_cmd - Commands supported by Diag group
> + *
> + * @XE_SYSCTRL_CMD_DIAG_RAS_ERR_INJECT: RAS error injection  */
> enum
> +xe_sysctrl_diag_cmd {
> +	XE_SYSCTRL_CMD_DIAG_RAS_ERR_INJECT		= 0x7E,
> +};
> +
> +/**
> + * struct xe_sysctrl_diag_ras_err_inj_req - DIAG_RAS_ERR_INJECT request
> +payload
> + *
> + * Request payload for XE_SYSCTRL_CMD_DIAG_RAS_ERR_INJECT. The
> mailbox
> +layer
> + * prepends the application message header before sending.
> + *
> + * @ras_block_id: RAS block (subsystem) to inject the error into
> + * @ras_sub_block_id: RAS sub-block (IP) within @ras_block_id
> + * @err_type: Type of test error to inject
> + * @reserved: Must be zero
> + * @params: Optional injection parameters (default 0)  */ struct
> +xe_sysctrl_diag_ras_err_inj_req {
> +	u16 ras_block_id;
> +	u16 ras_sub_block_id;
> +	u16 err_type;
> +	u16 reserved;
> +	u32 params;
> +} __packed;
> +
>  /**
>   * struct xe_sysctrl_app_status_req - Get application status request
>   *
> diff --git a/drivers/gpu/drm/xe/xe_sysctrl_types.h
> b/drivers/gpu/drm/xe/xe_sysctrl_types.h
> index 53d82e61383a..3a97a10d1b7d 100644
> --- a/drivers/gpu/drm/xe/xe_sysctrl_types.h
> +++ b/drivers/gpu/drm/xe/xe_sysctrl_types.h
> @@ -68,6 +68,9 @@ struct xe_sysctrl {
> 
>  		/** @debugfs.loopback: Loopback test entry */
>  		struct xe_sysctrl_debugfs_entry loopback;
> +
> +		/** @debugfs.ras_error_inject: RAS error injection test entry
> */
> +		struct xe_sysctrl_debugfs_entry ras_error_inject;
>  	} debugfs;
>  };
> 
> --
> 2.43.0