/*
 * kbdif.h -- Xen virtual keyboard/mouse
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Copyright (C) 2005 Anthony Liguori <aliguori@us.ibm.com>
 * Copyright (C) 2006 Red Hat, Inc., Markus Armbruster <armbru@redhat.com>
 */

#ifndef __XEN_PUBLIC_IO_KBDIF_H__
#define __XEN_PUBLIC_IO_KBDIF_H__

/* In events (backend -> frontend) */

/*
 * Frontends should ignore unknown in events.
 */

/* Pointer movement event */
#define XENKBD_TYPE_MOTION  1
/* Event type 2 currently not used */
/* Key event (includes pointer buttons) */
#define XENKBD_TYPE_KEY     3
/*
 * Pointer position event
 * Capable backend sets feature-abs-pointer in xenstore.
 * Frontend requests ot instead of XENKBD_TYPE_MOTION by setting
 * request-abs-update in xenstore.
 */
#define XENKBD_TYPE_POS     4

struct xenkbd_motion {
	uint8_t type;		/* XENKBD_TYPE_MOTION */
	int32_t rel_x;		/* relative X motion */
	int32_t rel_y;		/* relative Y motion */
	int32_t rel_z;		/* relative Z motion (wheel) */
};

struct xenkbd_key {
	uint8_t type;		/* XENKBD_TYPE_KEY */
	uint8_t pressed;	/* 1 if pressed; 0 otherwise */
	uint32_t keycode;	/* KEY_* from linux/input.h */
};

struct xenkbd_position {
	uint8_t type;		/* XENKBD_TYPE_POS */
	int32_t abs_x;		/* absolute X position (in FB pixels) */
	int32_t abs_y;		/* absolute Y position (in FB pixels) */
	int32_t rel_z;		/* relative Z motion (wheel) */
};

#define XENKBD_IN_EVENT_SIZE 40

union xenkbd_in_event {
	uint8_t type;
	struct xenkbd_motion motion;
	struct xenkbd_key key;
	struct xenkbd_position pos;
	char pad[XENKBD_IN_EVENT_SIZE];
};

/* Out events (frontend -> backend) */

/*
 * Out events may be sent only when requested by backend, and receipt
 * of an unknown out event is an error.
 * No out events currently defined.
 */

#define XENKBD_OUT_EVENT_SIZE 40

union xenkbd_out_event {
	uint8_t type;
	char pad[XENKBD_OUT_EVENT_SIZE];
};

/* shared page */

#define XENKBD_IN_RING_SIZE 2048
#define XENKBD_IN_RING_LEN (XENKBD_IN_RING_SIZE / XENKBD_IN_EVENT_SIZE)
#define XENKBD_IN_RING_OFFS 1024
#define XENKBD_IN_RING(page) \
	((union xenkbd_in_event *)((char *)(page) + XENKBD_IN_RING_OFFS))
#define XENKBD_IN_RING_REF(page, idx) \
	(XENKBD_IN_RING((page))[(idx) % XENKBD_IN_RING_LEN])

#define XENKBD_OUT_RING_SIZE 1024
#define XENKBD_OUT_RING_LEN (XENKBD_OUT_RING_SIZE / XENKBD_OUT_EVENT_SIZE)
#define XENKBD_OUT_RING_OFFS (XENKBD_IN_RING_OFFS + XENKBD_IN_RING_SIZE)
#define XENKBD_OUT_RING(page) \
	((union xenkbd_out_event *)((char *)(page) + XENKBD_OUT_RING_OFFS))
#define XENKBD_OUT_RING_REF(page, idx) \
	(XENKBD_OUT_RING((page))[(idx) % XENKBD_OUT_RING_LEN])

struct xenkbd_page {
	uint32_t in_cons, in_prod;
	uint32_t out_cons, out_prod;
};

#endif
'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-29 13:50:06 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>39cb2c9a316e77f6dfba96c543e55b6672d5a37e</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers?id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>98fe974ee4e20121253de7f61fc8d01bdb3821c1</a> /<a href='/cgit.cgi/linux/net-next.git/tree/drivers?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>drivers</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers?h=nds-private-remove&amp;id=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>2c5d9555d6d937966d79d4c6529a5f7b9206e405</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e&amp;id2=2c5d9555d6d937966d79d4c6529a5f7b9206e405'>diff</a>)</td></tr></table>
<div class='commit-subject'>drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()</div><div class='commit-msg'>I've seen this trigger twice now, where the i915_gem_object_to_ggtt()
call in intel_unpin_fb_obj() returns NULL, resulting in an oops
immediately afterwards as the (inlined) call to i915_vma_unpin_fence()
tries to dereference it.

It seems to be some race condition where the object is going away at
shutdown time, since both times happened when shutting down the X
server.  The call chains were different:

 - VT ioctl(KDSETMODE, KD_TEXT):

    intel_cleanup_plane_fb+0x5b/0xa0 [i915]
    drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper]
    intel_atomic_commit_tail+0x749/0xfe0 [i915]
    intel_atomic_commit+0x3cb/0x4f0 [i915]
    drm_atomic_commit+0x4b/0x50 [drm]
    restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper]
    drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper]
    drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper]
    intel_fbdev_set_par+0x18/0x70 [i915]
    fb_set_var+0x236/0x460
    fbcon_blank+0x30f/0x350
    do_unblank_screen+0xd2/0x1a0
    vt_ioctl+0x507/0x12a0
    tty_ioctl+0x355/0xc30
    do_vfs_ioctl+0xa3/0x5e0
    SyS_ioctl+0x79/0x90
    entry_SYSCALL_64_fastpath+0x13/0x94

 - i915 unpin_work workqueue:

    intel_unpin_work_fn+0x58/0x140 [i915]
    process_one_work+0x1f1/0x480
    worker_thread+0x48/0x4d0
    kthread+0x101/0x140

and this patch purely papers over the issue by adding a NULL pointer
check and a WARN_ON_ONCE() to avoid the oops that would then generally
make the machine unresponsive.

Other callers of i915_gem_object_to_ggtt() seem to also check for the
returned pointer being NULL and warn about it, so this clearly has
happened before in other places.

[ Reported it originally to the i915 developers on Jan 8, applying the
  ugly workaround on my own now after triggering the problem for the
  second time with no feedback.

  This is likely to be the same bug reported as

     https://bugs.freedesktop.org/show_bug.cgi?id=98829
     https://bugs.freedesktop.org/show_bug.cgi?id=99134

  which has a patch for the underlying problem, but it hasn't gotten to
  me, so I'm applying the workaround. ]

Cc: Daniel Vetter &lt;daniel.vetter@intel.com&gt;
Cc: Jani Nikula &lt;jani.nikula@linux.intel.com&gt;
Cc: Ville Syrjälä &lt;ville.syrjala@linux.intel.com&gt;
Cc: Chris Wilson &lt;chris@chris-wilson.co.uk&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Tvrtko Ursulin &lt;tvrtko.ursulin@intel.com&gt;
Cc: Imre Deak &lt;imre.deak@intel.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?h=nds-private-remove&amp;id=39cb2c9a316e77f6dfba96c543e55b6672d5a37e'>Diffstat</a> (limited to 'drivers')</div><table summary='diffstat' class='diffstat'>