<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/gpu, branch v5.4.48</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>drm/amdgpu: Sync with VM root BO when switching VM to CPU update mode</title>
<updated>2020-06-22T07:31:08+00:00</updated>
<author>
<name>Felix Kuehling</name>
<email>Felix.Kuehling@amd.com</email>
</author>
<published>2020-05-20T01:02:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5b8d09eeb4a627b5b936f45da3d8ea9c723e92f5'/>
<id>5b8d09eeb4a627b5b936f45da3d8ea9c723e92f5</id>
<content type='text'>
[ Upstream commit 90ca78deb004abe75b5024968a199acb96bb70f9 ]

This fixes an intermittent bug where a root PD clear operation still in
progress could overwrite a PDE update done by the CPU, resulting in a
VM fault.

Fixes: 108b4d928c03 ("drm/amd/amdgpu: Update VM function pointer")
Reported-by: Jay Cornwall &lt;Jay.Cornwall@amd.com&gt;
Tested-by: Jay Cornwall &lt;Jay.Cornwall@amd.com&gt;
Signed-off-by: Felix Kuehling &lt;Felix.Kuehling@amd.com&gt;
Reviewed-by: Christian König &lt;christian.koenig@amd.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 90ca78deb004abe75b5024968a199acb96bb70f9 ]

This fixes an intermittent bug where a root PD clear operation still in
progress could overwrite a PDE update done by the CPU, resulting in a
VM fault.

Fixes: 108b4d928c03 ("drm/amd/amdgpu: Update VM function pointer")
Reported-by: Jay Cornwall &lt;Jay.Cornwall@amd.com&gt;
Tested-by: Jay Cornwall &lt;Jay.Cornwall@amd.com&gt;
Signed-off-by: Felix Kuehling &lt;Felix.Kuehling@amd.com&gt;
Reviewed-by: Christian König &lt;christian.koenig@amd.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/amd/powerpay: Disable gfxoff when setting manual mode on picasso and raven</title>
<updated>2020-06-22T07:31:08+00:00</updated>
<author>
<name>chen gong</name>
<email>curry.gong@amd.com</email>
</author>
<published>2020-05-21T09:15:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b06a7dc9e5f65f163e7864e5e34d96300e8b07b3'/>
<id>b06a7dc9e5f65f163e7864e5e34d96300e8b07b3</id>
<content type='text'>
[ Upstream commit cbd2d08c7463e78d625a69e9db27ad3004cbbd99 ]

[Problem description]
1. Boot up picasso platform, launches desktop, Don't do anything (APU enter into "gfxoff" state)
2. Remote login to platform using SSH, then type the command line:
	sudo su -c "echo manual &gt; /sys/class/drm/card0/device/power_dpm_force_performance_level"
	sudo su -c "echo 2 &gt; /sys/class/drm/card0/device/pp_dpm_sclk" (fix SCLK to 1400MHz)
3. Move the mouse around in Window
4. Phenomenon :  The screen frozen

Tester will switch sclk level during glmark2 run time.
APU will enter "gfxoff" state intermittently during glmark2 run time.
The system got hanged if fix GFXCLK to 1400MHz when APU is in "gfxoff"
state.

[Debug]
1. Fix SCLK to X MHz
	1400: screen frozen, screen black, then OS will reboot.
	1300: screen frozen.
	1200: screen frozen, screen black.
	1100: screen frozen, screen black, then OS will reboot.
	1000: screen frozen, screen black.
	900:  screen frozen, screen black, then OS will reboot.
	800:  Situation Nomal, issue disappear.
	700:  Situation Nomal, issue disappear.
2. SBIOS setting: AMD CBS --&gt; SMU Debug Options --&gt;SMU Debug --&gt; "GFX DLDO Psm Margin Control":
	50 : Situation Nomal, issue disappear.
	45 : Situation Nomal, issue disappear.
	40 : Situation Nomal, issue disappear.
	35 : Situation Nomal, issue disappear.
	30 : screen black.
	25 : screen frozen, then blurred screen.
	20 : screen frozen.
	15 : screen black.
	10 : screen frozen.
	5  : screen frozen, then blurred screen.
3. Disable GFXOFF feature
	Situation Nomal, issue disappear.

[Why]
Through a period of time debugging with Sys Eng team and SMU team, Sys
Eng team said this is voltage/frequency marginal issue not a F/W or H/W
bug. This experiment proves that default targetPsm [for f=1400MHz] is
not sufficient when GFXOFF is enabled on Picasso.

SMU team think it is an odd test conditions to force sclk="1400MHz" when
GPU is in "gfxoff" state，then wake up the GFX. SCLK should be in the
"lowest frequency" when gfxoff.

[How]
Disable gfxoff when setting manual mode.
Enable gfxoff when setting other mode(exiting manual mode) again.

By the way, from the user point of view, now that user switch to manual
mode and force SCLK Frequency, he don't want SCLK be controlled by
workload.It becomes meaningless to "switch to manual mode" if APU enter "gfxoff"
due to lack of workload at this point.

Tips: Same issue observed on Raven.

Signed-off-by: chen gong &lt;curry.gong@amd.com&gt;
Reviewed-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit cbd2d08c7463e78d625a69e9db27ad3004cbbd99 ]

[Problem description]
1. Boot up picasso platform, launches desktop, Don't do anything (APU enter into "gfxoff" state)
2. Remote login to platform using SSH, then type the command line:
	sudo su -c "echo manual &gt; /sys/class/drm/card0/device/power_dpm_force_performance_level"
	sudo su -c "echo 2 &gt; /sys/class/drm/card0/device/pp_dpm_sclk" (fix SCLK to 1400MHz)
3. Move the mouse around in Window
4. Phenomenon :  The screen frozen

Tester will switch sclk level during glmark2 run time.
APU will enter "gfxoff" state intermittently during glmark2 run time.
The system got hanged if fix GFXCLK to 1400MHz when APU is in "gfxoff"
state.

[Debug]
1. Fix SCLK to X MHz
	1400: screen frozen, screen black, then OS will reboot.
	1300: screen frozen.
	1200: screen frozen, screen black.
	1100: screen frozen, screen black, then OS will reboot.
	1000: screen frozen, screen black.
	900:  screen frozen, screen black, then OS will reboot.
	800:  Situation Nomal, issue disappear.
	700:  Situation Nomal, issue disappear.
2. SBIOS setting: AMD CBS --&gt; SMU Debug Options --&gt;SMU Debug --&gt; "GFX DLDO Psm Margin Control":
	50 : Situation Nomal, issue disappear.
	45 : Situation Nomal, issue disappear.
	40 : Situation Nomal, issue disappear.
	35 : Situation Nomal, issue disappear.
	30 : screen black.
	25 : screen frozen, then blurred screen.
	20 : screen frozen.
	15 : screen black.
	10 : screen frozen.
	5  : screen frozen, then blurred screen.
3. Disable GFXOFF feature
	Situation Nomal, issue disappear.

[Why]
Through a period of time debugging with Sys Eng team and SMU team, Sys
Eng team said this is voltage/frequency marginal issue not a F/W or H/W
bug. This experiment proves that default targetPsm [for f=1400MHz] is
not sufficient when GFXOFF is enabled on Picasso.

SMU team think it is an odd test conditions to force sclk="1400MHz" when
GPU is in "gfxoff" state，then wake up the GFX. SCLK should be in the
"lowest frequency" when gfxoff.

[How]
Disable gfxoff when setting manual mode.
Enable gfxoff when setting other mode(exiting manual mode) again.

By the way, from the user point of view, now that user switch to manual
mode and force SCLK Frequency, he don't want SCLK be controlled by
workload.It becomes meaningless to "switch to manual mode" if APU enter "gfxoff"
due to lack of workload at this point.

Tips: Same issue observed on Raven.

Signed-off-by: chen gong &lt;curry.gong@amd.com&gt;
Reviewed-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/mcde: dsi: Fix return value check in mcde_dsi_bind()</title>
<updated>2020-06-22T07:31:05+00:00</updated>
<author>
<name>Wei Yongjun</name>
<email>weiyongjun1@huawei.com</email>
</author>
<published>2020-04-30T07:31:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=095e7a6a326c1caf0e83d086e4d42f2980f19f9d'/>
<id>095e7a6a326c1caf0e83d086e4d42f2980f19f9d</id>
<content type='text'>
[ Upstream commit 761e9f4f80a21a4b845097027030bef863001636 ]

The of_drm_find_bridge() function returns NULL on error, it doesn't return
error pointers so this check doesn't work.

Fixes: 5fc537bfd000 ("drm/mcde: Add new driver for ST-Ericsson MCDE")
Signed-off-by: Wei Yongjun &lt;weiyongjun1@huawei.com&gt;
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20200430073145.52321-1-weiyongjun1@huawei.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 761e9f4f80a21a4b845097027030bef863001636 ]

The of_drm_find_bridge() function returns NULL on error, it doesn't return
error pointers so this check doesn't work.

Fixes: 5fc537bfd000 ("drm/mcde: Add new driver for ST-Ericsson MCDE")
Signed-off-by: Wei Yongjun &lt;weiyongjun1@huawei.com&gt;
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20200430073145.52321-1-weiyongjun1@huawei.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/mediatek: set dpi pin mode to gpio low to avoid leakage current</title>
<updated>2020-06-22T07:30:58+00:00</updated>
<author>
<name>Jitao Shi</name>
<email>jitao.shi@mediatek.com</email>
</author>
<published>2020-04-15T01:13:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6315839f14b97ea0ad2dd08af7984df0058cf011'/>
<id>6315839f14b97ea0ad2dd08af7984df0058cf011</id>
<content type='text'>
[ Upstream commit 6bd4763fd532cff43f9b15704f324c45a9806f53 ]

Config dpi pins mode to output and pull low when dpi is disabled.
Aovid leakage current from some dpi pins (Hsync Vsync DE ... ).

Signed-off-by: Jitao Shi &lt;jitao.shi@mediatek.com&gt;
Signed-off-by: Chun-Kuang Hu &lt;chunkuang.hu@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6bd4763fd532cff43f9b15704f324c45a9806f53 ]

Config dpi pins mode to output and pull low when dpi is disabled.
Aovid leakage current from some dpi pins (Hsync Vsync DE ... ).

Signed-off-by: Jitao Shi &lt;jitao.shi@mediatek.com&gt;
Signed-off-by: Chun-Kuang Hu &lt;chunkuang.hu@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm: rcar-du: Set primary plane zpos immutably at initializing</title>
<updated>2020-06-22T07:30:53+00:00</updated>
<author>
<name>Tomohito Esaki</name>
<email>etom@igel.co.jp</email>
</author>
<published>2020-04-01T06:11:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=00f73938ef655908838b332df33e6b25d7080fd5'/>
<id>00f73938ef655908838b332df33e6b25d7080fd5</id>
<content type='text'>
[ Upstream commit 7982471d01aac33994276bf567c8f1f3a137648a ]

According to drm_plane_create_zpos_property() function documentation,
all planes zpos range should be set if zpos property is supported.
However, the rcar-du driver didn't set primary plane zpos range. Since
the primary plane's zpos is fixed, set it immutably.

Reported-by: Yoshihito Ogawa &lt;yoshihito.ogawa.kc@renesas.com&gt;
Reported-by: Koji Matsuoka &lt;koji.matsuoka.xm@renesas.com&gt;
Signed-off-by: Tomohito Esaki &lt;etom@igel.co.jp&gt;
Reviewed-by: Laurent Pinchart &lt;laurent.pinchart+renesas@ideasonboard.com&gt;
Reviewed-by: Daniel Stone &lt;daniels@collabora.com&gt;
[Turn continue into if ... else ...]
Signed-off-by: Laurent Pinchart &lt;laurent.pinchart+renesas@ideasonboard.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 7982471d01aac33994276bf567c8f1f3a137648a ]

According to drm_plane_create_zpos_property() function documentation,
all planes zpos range should be set if zpos property is supported.
However, the rcar-du driver didn't set primary plane zpos range. Since
the primary plane's zpos is fixed, set it immutably.

Reported-by: Yoshihito Ogawa &lt;yoshihito.ogawa.kc@renesas.com&gt;
Reported-by: Koji Matsuoka &lt;koji.matsuoka.xm@renesas.com&gt;
Signed-off-by: Tomohito Esaki &lt;etom@igel.co.jp&gt;
Reviewed-by: Laurent Pinchart &lt;laurent.pinchart+renesas@ideasonboard.com&gt;
Reviewed-by: Daniel Stone &lt;daniels@collabora.com&gt;
[Turn continue into if ... else ...]
Signed-off-by: Laurent Pinchart &lt;laurent.pinchart+renesas@ideasonboard.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/amdgpu: Init data to avoid oops while reading pp_num_states.</title>
<updated>2020-06-22T07:30:50+00:00</updated>
<author>
<name>limingyu</name>
<email>limingyu@uniontech.com</email>
</author>
<published>2020-04-22T09:01:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=614722f1ffd23de075900ef58edce1450acfb6ed'/>
<id>614722f1ffd23de075900ef58edce1450acfb6ed</id>
<content type='text'>
[ Upstream commit 6f81b2d047c59eb77cd04795a44245d6a52cdaec ]

For chip like CHIP_OLAND with si enabled(amdgpu.si_support=1),
the amdgpu will expose pp_num_states to the /sys directory.
In this moment, read the pp_num_states file will excute the
amdgpu_get_pp_num_states func. In our case, the data hasn't
been initialized, so the kernel will access some ilegal
address, trigger the segmentfault and system will reboot soon:

    uos@uos-PC:~$ cat /sys/devices/pci0000\:00/0000\:00\:00.0/0000\:01\:00
    .0/pp_num_states

    Message from syslogd@uos-PC at Apr 22 09:26:20 ...
     kernel:[   82.154129] Internal error: Oops: 96000004 [#1] SMP

This patch aims to fix this problem, avoid that reading file
triggers the kernel sementfault.

Signed-off-by: limingyu &lt;limingyu@uniontech.com&gt;
Signed-off-by: zhoubinbin &lt;zhoubinbin@uniontech.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6f81b2d047c59eb77cd04795a44245d6a52cdaec ]

For chip like CHIP_OLAND with si enabled(amdgpu.si_support=1),
the amdgpu will expose pp_num_states to the /sys directory.
In this moment, read the pp_num_states file will excute the
amdgpu_get_pp_num_states func. In our case, the data hasn't
been initialized, so the kernel will access some ilegal
address, trigger the segmentfault and system will reboot soon:

    uos@uos-PC:~$ cat /sys/devices/pci0000\:00/0000\:00\:00.0/0000\:01\:00
    .0/pp_num_states

    Message from syslogd@uos-PC at Apr 22 09:26:20 ...
     kernel:[   82.154129] Internal error: Oops: 96000004 [#1] SMP

This patch aims to fix this problem, avoid that reading file
triggers the kernel sementfault.

Signed-off-by: limingyu &lt;limingyu@uniontech.com&gt;
Signed-off-by: zhoubinbin &lt;zhoubinbin@uniontech.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm: bridge: adv7511: Extend list of audio sample rates</title>
<updated>2020-06-22T07:30:49+00:00</updated>
<author>
<name>Bogdan Togorean</name>
<email>bogdan.togorean@analog.com</email>
</author>
<published>2020-04-13T11:35:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=22710f6c35a30c67f32bcaaa1f013f7ed5a4e9f7'/>
<id>22710f6c35a30c67f32bcaaa1f013f7ed5a4e9f7</id>
<content type='text'>
[ Upstream commit b97b6a1f6e14a25d1e1ca2a46c5fa3e2ca374e22 ]

ADV7511 support sample rates up to 192kHz. CTS and N parameters should
be computed accordingly so this commit extend the list up to maximum
supported sample rate.

Signed-off-by: Bogdan Togorean &lt;bogdan.togorean@analog.com&gt;
Reviewed-by: Andrzej Hajda &lt;a.hajda@samsung.com&gt;
Signed-off-by: Andrzej Hajda &lt;a.hajda@samsung.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20200413113513.86091-2-bogdan.togorean@analog.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit b97b6a1f6e14a25d1e1ca2a46c5fa3e2ca374e22 ]

ADV7511 support sample rates up to 192kHz. CTS and N parameters should
be computed accordingly so this commit extend the list up to maximum
supported sample rate.

Signed-off-by: Bogdan Togorean &lt;bogdan.togorean@analog.com&gt;
Reviewed-by: Andrzej Hajda &lt;a.hajda@samsung.com&gt;
Signed-off-by: Andrzej Hajda &lt;a.hajda@samsung.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20200413113513.86091-2-bogdan.togorean@analog.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/amdgpu: fix and cleanup amdgpu_gem_object_close v4</title>
<updated>2020-06-22T07:30:49+00:00</updated>
<author>
<name>Christian König</name>
<email>christian.koenig@amd.com</email>
</author>
<published>2020-03-12T11:03:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6fc5719b85ec044dc0824930bc375ab23991577c'/>
<id>6fc5719b85ec044dc0824930bc375ab23991577c</id>
<content type='text'>
[ Upstream commit 82c416b13cb7d22b96ec0888b296a48dff8a09eb ]

The problem is that we can't add the clear fence to the BO
when there is an exclusive fence on it since we can't
guarantee the the clear fence will complete after the
exclusive one.

To fix this refactor the function and also add the exclusive
fence as shared to the resv object.

v2: fix warning
v3: add excl fence as shared instead
v4: squash in fix for fence handling in amdgpu_gem_object_close

Signed-off-by: Christian König &lt;christian.koenig@amd.com&gt;
Reviewed-by: xinhui pan &lt;xinhui.pan@amd.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 82c416b13cb7d22b96ec0888b296a48dff8a09eb ]

The problem is that we can't add the clear fence to the BO
when there is an exclusive fence on it since we can't
guarantee the the clear fence will complete after the
exclusive one.

To fix this refactor the function and also add the exclusive
fence as shared to the resv object.

v2: fix warning
v3: add excl fence as shared instead
v4: squash in fix for fence handling in amdgpu_gem_object_close

Signed-off-by: Christian König &lt;christian.koenig@amd.com&gt;
Reviewed-by: xinhui pan &lt;xinhui.pan@amd.com&gt;
Signed-off-by: Alex Deucher &lt;alexander.deucher@amd.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>drm/vkms: Hold gem object while still in-use</title>
<updated>2020-06-17T14:40:36+00:00</updated>
<author>
<name>Ezequiel Garcia</name>
<email>ezequiel@collabora.com</email>
</author>
<published>2020-04-27T21:44:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=b21602a88ef1fdd715d1ec0d5a697687e7549a16'/>
<id>b21602a88ef1fdd715d1ec0d5a697687e7549a16</id>
<content type='text'>
commit 0ea2ea42b31abc1141f2fd3911f952a97d401fcb upstream.

We need to keep the reference to the drm_gem_object
until the last access by vkms_dumb_create.

Therefore, the put the object after it is used.

This fixes a use-after-free issue reported by syzbot.

While here, change vkms_gem_create() symbol to static.

Reported-and-tested-by: syzbot+e3372a2afe1e7ef04bc7@syzkaller.appspotmail.com
Signed-off-by: Ezequiel Garcia &lt;ezequiel@collabora.com&gt;
Reviewed-by: Rodrigo Siqueira &lt;Rodrigo.Siqueira@amd.com&gt;
Signed-off-by: Rodrigo Siqueira &lt;rodrigosiqueiramelo@gmail.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20200427214405.13069-1-ezequiel@collabora.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 0ea2ea42b31abc1141f2fd3911f952a97d401fcb upstream.

We need to keep the reference to the drm_gem_object
until the last access by vkms_dumb_create.

Therefore, the put the object after it is used.

This fixes a use-after-free issue reported by syzbot.

While here, change vkms_gem_create() symbol to static.

Reported-and-tested-by: syzbot+e3372a2afe1e7ef04bc7@syzkaller.appspotmail.com
Signed-off-by: Ezequiel Garcia &lt;ezequiel@collabora.com&gt;
Reviewed-by: Rodrigo Siqueira &lt;Rodrigo.Siqueira@amd.com&gt;
Signed-off-by: Rodrigo Siqueira &lt;rodrigosiqueiramelo@gmail.com&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20200427214405.13069-1-ezequiel@collabora.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>gup: document and work around "COW can break either way" issue</title>
<updated>2020-06-17T14:40:30+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-05-28T01:29:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1027dc04f557328eb7b7b7eea48698377a959157'/>
<id>1027dc04f557328eb7b7b7eea48698377a959157</id>
<content type='text'>
commit 17839856fd588f4ab6b789f482ed3ffd7c403e1f upstream.

Doing a "get_user_pages()" on a copy-on-write page for reading can be
ambiguous: the page can be COW'ed at any time afterwards, and the
direction of a COW event isn't defined.

Yes, whoever writes to it will generally do the COW, but if the thread
that did the get_user_pages() unmapped the page before the write (and
that could happen due to memory pressure in addition to any outright
action), the writer could also just take over the old page instead.

End result: the get_user_pages() call might result in a page pointer
that is no longer associated with the original VM, and is associated
with - and controlled by - another VM having taken it over instead.

So when doing a get_user_pages() on a COW mapping, the only really safe
thing to do would be to break the COW when getting the page, even when
only getting it for reading.

At the same time, some users simply don't even care.

For example, the perf code wants to look up the page not because it
cares about the page, but because the code simply wants to look up the
physical address of the access for informational purposes, and doesn't
really care about races when a page might be unmapped and remapped
elsewhere.

This adds logic to force a COW event by setting FOLL_WRITE on any
copy-on-write mapping when FOLL_GET (or FOLL_PIN) is used to get a page
pointer as a result.

The current semantics end up being:

 - __get_user_pages_fast(): no change. If you don't ask for a write,
   you won't break COW. You'd better know what you're doing.

 - get_user_pages_fast(): the fast-case "look it up in the page tables
   without anything getting mmap_sem" now refuses to follow a read-only
   page, since it might need COW breaking.  Which happens in the slow
   path - the fast path doesn't know if the memory might be COW or not.

 - get_user_pages() (including the slow-path fallback for gup_fast()):
   for a COW mapping, turn on FOLL_WRITE for FOLL_GET/FOLL_PIN, with
   very similar semantics to FOLL_FORCE.

If it turns out that we want finer granularity (ie "only break COW when
it might actually matter" - things like the zero page are special and
don't need to be broken) we might need to push these semantics deeper
into the lookup fault path.  So if people care enough, it's possible
that we might end up adding a new internal FOLL_BREAK_COW flag to go
with the internal FOLL_COW flag we already have for tracking "I had a
COW".

Alternatively, if it turns out that different callers might want to
explicitly control the forced COW break behavior, we might even want to
make such a flag visible to the users of get_user_pages() instead of
using the above default semantics.

But for now, this is mostly commentary on the issue (this commit message
being a lot bigger than the patch, and that patch in turn is almost all
comments), with that minimal "enable COW breaking early" logic using the
existing FOLL_WRITE behavior.

[ It might be worth noting that we've always had this ambiguity, and it
  could arguably be seen as a user-space issue.

  You only get private COW mappings that could break either way in
  situations where user space is doing cooperative things (ie fork()
  before an execve() etc), but it _is_ surprising and very subtle, and
  fork() is supposed to give you independent address spaces.

  So let's treat this as a kernel issue and make the semantics of
  get_user_pages() easier to understand. Note that obviously a true
  shared mapping will still get a page that can change under us, so this
  does _not_ mean that get_user_pages() somehow returns any "stable"
  page ]

Reported-by: Jann Horn &lt;jannh@google.com&gt;
Tested-by: Christoph Hellwig &lt;hch@lst.de&gt;
Acked-by: Oleg Nesterov &lt;oleg@redhat.com&gt;
Acked-by: Kirill Shutemov &lt;kirill@shutemov.name&gt;
Acked-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 17839856fd588f4ab6b789f482ed3ffd7c403e1f upstream.

Doing a "get_user_pages()" on a copy-on-write page for reading can be
ambiguous: the page can be COW'ed at any time afterwards, and the
direction of a COW event isn't defined.

Yes, whoever writes to it will generally do the COW, but if the thread
that did the get_user_pages() unmapped the page before the write (and
that could happen due to memory pressure in addition to any outright
action), the writer could also just take over the old page instead.

End result: the get_user_pages() call might result in a page pointer
that is no longer associated with the original VM, and is associated
with - and controlled by - another VM having taken it over instead.

So when doing a get_user_pages() on a COW mapping, the only really safe
thing to do would be to break the COW when getting the page, even when
only getting it for reading.

At the same time, some users simply don't even care.

For example, the perf code wants to look up the page not because it
cares about the page, but because the code simply wants to look up the
physical address of the access for informational purposes, and doesn't
really care about races when a page might be unmapped and remapped
elsewhere.

This adds logic to force a COW event by setting FOLL_WRITE on any
copy-on-write mapping when FOLL_GET (or FOLL_PIN) is used to get a page
pointer as a result.

The current semantics end up being:

 - __get_user_pages_fast(): no change. If you don't ask for a write,
   you won't break COW. You'd better know what you're doing.

 - get_user_pages_fast(): the fast-case "look it up in the page tables
   without anything getting mmap_sem" now refuses to follow a read-only
   page, since it might need COW breaking.  Which happens in the slow
   path - the fast path doesn't know if the memory might be COW or not.

 - get_user_pages() (including the slow-path fallback for gup_fast()):
   for a COW mapping, turn on FOLL_WRITE for FOLL_GET/FOLL_PIN, with
   very similar semantics to FOLL_FORCE.

If it turns out that we want finer granularity (ie "only break COW when
it might actually matter" - things like the zero page are special and
don't need to be broken) we might need to push these semantics deeper
into the lookup fault path.  So if people care enough, it's possible
that we might end up adding a new internal FOLL_BREAK_COW flag to go
with the internal FOLL_COW flag we already have for tracking "I had a
COW".

Alternatively, if it turns out that different callers might want to
explicitly control the forced COW break behavior, we might even want to
make such a flag visible to the users of get_user_pages() instead of
using the above default semantics.

But for now, this is mostly commentary on the issue (this commit message
being a lot bigger than the patch, and that patch in turn is almost all
comments), with that minimal "enable COW breaking early" logic using the
existing FOLL_WRITE behavior.

[ It might be worth noting that we've always had this ambiguity, and it
  could arguably be seen as a user-space issue.

  You only get private COW mappings that could break either way in
  situations where user space is doing cooperative things (ie fork()
  before an execve() etc), but it _is_ surprising and very subtle, and
  fork() is supposed to give you independent address spaces.

  So let's treat this as a kernel issue and make the semantics of
  get_user_pages() easier to understand. Note that obviously a true
  shared mapping will still get a page that can change under us, so this
  does _not_ mean that get_user_pages() somehow returns any "stable"
  page ]

Reported-by: Jann Horn &lt;jannh@google.com&gt;
Tested-by: Christoph Hellwig &lt;hch@lst.de&gt;
Acked-by: Oleg Nesterov &lt;oleg@redhat.com&gt;
Acked-by: Kirill Shutemov &lt;kirill@shutemov.name&gt;
Acked-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
</feed>
