Linux Virtualization - Oct 2018 - [PATCH] qxl: fix null-pointer crash during suspend

On Tue, Sep 04, 2018 at 10:27:47PM +0200, Peter Wu
wrote:
> "crtc->helper_private" is not initialized by the QXL driver
and thus the
This is still initialized, it's the ->disable that goes boom. At least
the
call to drm_crtc_helper_add is still there. The ->disable was removed in:

commit 64581714b58bc3e16ede8dc37a025c3aa0e0eef1
Author: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
Date:   Fri Jun 30 12:36:45 2017 +0300

    drm: Convert atomic drivers from CRTC .disable() to .atomic_disable()

Fixes: 64581714b58b ("drm: Convert atomic drivers from CRTC .disable() to
.atomic_disable()")
Cc: <stable at vger.kernel.org> # v4.14+
Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

I'll let Gerd pick this one up, after some testing. Also adding Laurent.
-Daniel
> "crtc_funcs->disable" call would crash (resulting in suspend
failure).
> Fix this by converting the suspend/resume functions to use the
> drm_mode_config_helper_* helpers.
> 
> Tested system sleep with QEMU 3.0 using "echo mem >
/sys/power/state".
> During suspend the following message is visible from QEMU:
> 
>     spice/server/display-channel.c:2425:display_channel_validate_surface:
canvas address is 0x7fd05da68308 for 0 (and is NULL)
>     spice/server/display-channel.c:2426:display_channel_validate_surface:
failed on 0
> 
> This seems to be triggered by QXL_IO_NOTIFY_CMD after
> QXL_IO_DESTROY_PRIMARY_ASYNC, but aside from the warning things still
> seem to work (tested with both the GTK and -spice options).
> 
> Signed-off-by: Peter Wu <peter at lekensteyn.nl>
> ---
> Hi,
> 
> I found this issue while trying to suspend a VM that uses QXL. In order to
see
> the stack trace over serial, boot with no_console_suspend. Searching for
> "qxl_drm_freeze" showed one recent report from Alan:
> https://lkml.kernel.org/r/891e334c-cf19-032c-b996-59ac166fcde1 at gmail.com
> 
> Kind regards,
> Peter
> ---
>  drivers/gpu/drm/qxl/qxl_drv.c | 26 +++++---------------------
>  1 file changed, 5 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> index 2445e75cf7ea..d00f45eed03c 100644
> --- a/drivers/gpu/drm/qxl/qxl_drv.c
> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> @@ -136,20 +136,11 @@ static int qxl_drm_freeze(struct drm_device *dev)
>  {
>  	struct pci_dev *pdev = dev->pdev;
>  	struct qxl_device *qdev = dev->dev_private;
> -	struct drm_crtc *crtc;
> -
> -	drm_kms_helper_poll_disable(dev);
> -
> -	console_lock();
> -	qxl_fbdev_set_suspend(qdev, 1);
> -	console_unlock();
> +	int ret;
>  
> -	/* unpin the front buffers */
> -	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> -		const struct drm_crtc_helper_funcs *crtc_funcs =
crtc->helper_private;
> -		if (crtc->enabled)
> -			(*crtc_funcs->disable)(crtc);
> -	}
> +	ret = drm_mode_config_helper_suspend(dev);
> +	if (ret)
> +		return ret;
>  
>  	qxl_destroy_monitors_object(qdev);
>  	qxl_surf_evict(qdev);
> @@ -175,14 +166,7 @@ static int qxl_drm_resume(struct drm_device *dev, bool
thaw)
>  	}
>  
>  	qxl_create_monitors_object(qdev);
> -	drm_helper_resume_force_mode(dev);
> -
> -	console_lock();
> -	qxl_fbdev_set_suspend(qdev, 0);
> -	console_unlock();
> -
> -	drm_kms_helper_poll_enable(dev);
> -	return 0;
> +	return drm_mode_config_helper_resume(dev);
>  }
>  
>  static int qxl_pm_suspend(struct device *dev)
> -- 
> 2.18.0
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Hello,

On Tuesday, 2 October 2018 11:14:22 EEST Daniel Vetter
wrote:
> On Tue, Sep 04, 2018 at 10:27:47PM +0200, Peter Wu wrote:
> > "crtc->helper_private" is not initialized by the QXL
driver and thus the
> 
> This is still initialized, it's the ->disable that goes boom. At
least the
> call to drm_crtc_helper_add is still there. The ->disable was removed
in:
> 
> commit 64581714b58bc3e16ede8dc37a025c3aa0e0eef1
> Author: Laurent Pinchart <laurent.pinchart+renesas at
ideasonboard.com>
> Date:   Fri Jun 30 12:36:45 2017 +0300
> 
>     drm: Convert atomic drivers from CRTC .disable() to .atomic_disable()
> 
> Fixes: 64581714b58b ("drm: Convert atomic drivers from CRTC .disable()
to
> .atomic_disable()") Cc: <stable at vger.kernel.org> # v4.14+
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> I'll let Gerd pick this one up, after some testing. Also adding
Laurent.
Sorry for breaking it :-( Please let me know if there's something I can do
to
help.
> > "crtc_funcs->disable" call would crash (resulting in
suspend failure).
> > Fix this by converting the suspend/resume functions to use the
> > drm_mode_config_helper_* helpers.
> > 
> > Tested system sleep with QEMU 3.0 using "echo mem >
/sys/power/state".
> > 
> > During suspend the following message is visible from QEMU:
> >    
spice/server/display-channel.c:2425:display_channel_validate_surface:
> >     canvas address is 0x7fd05da68308 for 0 (and is NULL)
> >    
spice/server/display-channel.c:2426:display_channel_validate_surface:
> >     failed on 0> 
> > This seems to be triggered by QXL_IO_NOTIFY_CMD after
> > QXL_IO_DESTROY_PRIMARY_ASYNC, but aside from the warning things still
> > seem to work (tested with both the GTK and -spice options).
> > 
> > Signed-off-by: Peter Wu <peter at lekensteyn.nl>
> > ---
> > Hi,
> > 
> > I found this issue while trying to suspend a VM that uses QXL. In
order to
> > see the stack trace over serial, boot with no_console_suspend.
Searching
> > for "qxl_drm_freeze" showed one recent report from Alan:
> > https://lkml.kernel.org/r/891e334c-cf19-032c-b996-59ac166fcde1 at
gmail.com
> > 
> > Kind regards,
> > Peter
> > ---
> > 
> >  drivers/gpu/drm/qxl/qxl_drv.c | 26 +++++---------------------
> >  1 file changed, 5 insertions(+), 21 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/qxl/qxl_drv.c
b/drivers/gpu/drm/qxl/qxl_drv.c
> > index 2445e75cf7ea..d00f45eed03c 100644
> > --- a/drivers/gpu/drm/qxl/qxl_drv.c
> > +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> > @@ -136,20 +136,11 @@ static int qxl_drm_freeze(struct drm_device
*dev)
> > 
> >  {
> >  
> >  	struct pci_dev *pdev = dev->pdev;
> >  	struct qxl_device *qdev = dev->dev_private;
> > 
> > -	struct drm_crtc *crtc;
> > -
> > -	drm_kms_helper_poll_disable(dev);
> > -
> > -	console_lock();
> > -	qxl_fbdev_set_suspend(qdev, 1);
> > -	console_unlock();
> > +	int ret;
> > 
> > -	/* unpin the front buffers */
> > -	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
{
> > -		const struct drm_crtc_helper_funcs *crtc_funcs = crtc-
>helper_private;
> > -		if (crtc->enabled)
> > -			(*crtc_funcs->disable)(crtc);
> > -	}
> > +	ret = drm_mode_config_helper_suspend(dev);
> > +	if (ret)
> > +		return ret;
> > 
> >  	qxl_destroy_monitors_object(qdev);
> >  	qxl_surf_evict(qdev);
> > 
> > @@ -175,14 +166,7 @@ static int qxl_drm_resume(struct drm_device *dev,
> > bool thaw)> 
> >  	}
> >  	
> >  	qxl_create_monitors_object(qdev);
> > 
> > -	drm_helper_resume_force_mode(dev);
> > -
> > -	console_lock();
> > -	qxl_fbdev_set_suspend(qdev, 0);
> > -	console_unlock();
> > -
> > -	drm_kms_helper_poll_enable(dev);
> > -	return 0;
> > +	return drm_mode_config_helper_resume(dev);
> > 
> >  }
> >  
> >  static int qxl_pm_suspend(struct device *dev)

-- 
Regards,

Laurent Pinchart