Commit 4ca1fd41 authored by Lucas De Marchi's avatar Lucas De Marchi
Browse files

drm/xe: Fix fault on fd close after unbind 

If userspace holds an fd open, unbinds the device and then closes it,
the driver shouldn't try to access the hardware. Protect it by using
drm_dev_enter()/drm_dev_exit(). This fixes the following page fault:

<6> [IGT] xe_wedged: exiting, ret=98
<1> BUG: unable to handle page fault for address: ffffc901bc5e508c
<1> #PF: supervisor read access in kernel mode
<1> #PF: error_code(0x0000) - not-present page
...
<4>   xe_lrc_update_timestamp+0x1c/0xd0 [xe]
<4>   xe_exec_queue_update_run_ticks+0x50/0xb0 [xe]
<4>   xe_exec_queue_fini+0x16/0xb0 [xe]
<4>   __guc_exec_queue_fini_async+0xc4/0x190 [xe]
<4>   guc_exec_queue_fini_async+0xa0/0xe0 [xe]
<4>   guc_exec_queue_fini+0x23/0x40 [xe]
<4>   xe_exec_queue_destroy+0xb3/0xf0 [xe]
<4>   xe_file_close+0xd4/0x1a0 [xe]
<4>   drm_file_free+0x210/0x280 [drm]
<4>   drm_close_helper.isra.0+0x6d/0x80 [drm]
<4>   drm_release_noglobal+0x20/0x90 [drm]

Fixes: 83db047d ("drm/xe: Stop accumulating LRC timestamp on job_free")
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3421


Reviewed-by: default avatarUmesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241218053122.2730195-1-lucas.demarchi@intel.com


Signed-off-by: default avatarLucas De Marchi <lucas.demarchi@intel.com>
parent 2f12e9c0

drivers/gpu/drm/xe/xe_exec_queue.c

+9 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/nospec.h>



#include <drm/drm_device.h>

#include <drm/drm_drv.h>

#include <drm/drm_file.h>

#include <uapi/drm/xe_drm.h>
@@ -768,9 +769,11 @@ bool xe_exec_queue_is_idle(struct xe_exec_queue *q) 
 */

void xe_exec_queue_update_run_ticks(struct xe_exec_queue *q)

{

	struct xe_device *xe = gt_to_xe(q->gt);

	struct xe_file *xef;

	struct xe_lrc *lrc;

	u32 old_ts, new_ts;

	int idx;



	/*

	 * Jobs that are run during driver load may use an exec_queue, but are
@@ -780,6 +783,10 @@ void xe_exec_queue_update_run_ticks(struct xe_exec_queue *q) 
	if (!q->vm || !q->vm->xef)

		return;



	/* Synchronize with unbind while holding the xe file open */

	if (!drm_dev_enter(&xe->drm, &idx))

		return;



	xef = q->vm->xef;



	/*
@@ -793,6 +800,8 @@ void xe_exec_queue_update_run_ticks(struct xe_exec_queue *q) 
	lrc = q->lrc[0];

	new_ts = xe_lrc_update_timestamp(lrc, &old_ts);

	xef->run_ticks[q->class] += (new_ts - old_ts) * q->width;



	drm_dev_exit(idx);

}



/**