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

On Fri, Aug 07, 2026 at 11:15:59AM -0400, Gupta, Anshuman wrote:
> 
> 
> > -----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 ? 

I agree with this. It is better not even register the file if the
firmware is not loaded. So it doesn't even appear in the filesystem.

> 
> 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
>