From: Peng Fan <[email protected]>
If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
will not be able to get correct results. With CONFIG_DEBUG_VM and
CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
[ 3.536043] ------------[ cut here ]------------
[ 3.540716] virt_to_phys used for non-linear address: 000000007fc4f540 (0xffff800086001000)
[ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x68/0x98
[ 3.565455] Modules linked in:
[ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted 6.6.23-06226-g4986cc3e1b75-dirty #250
[ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
[ 3.582452] Workqueue: events_unbound deferred_probe_work_func
[ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 3.595233] pc : __virt_to_phys+0x68/0x98
[ 3.599246] lr : __virt_to_phys+0x68/0x98
[ 3.603276] sp : ffff800083603990
[ 3.677939] Call trace:
[ 3.680393] __virt_to_phys+0x68/0x98
[ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
[ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
[ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
[ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
[ 3.705161] drm_client_register+0x60/0xb0
[ 3.709269] drm_fbdev_dma_setup+0x94/0x148
So add a check 'is_vmalloc_addr'.
Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers")
Signed-off-by: Peng Fan <[email protected]>
---
drivers/gpu/drm/drm_fbdev_dma.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c
index 6c9427bb4053..9e2eddb6eb5c 100644
--- a/drivers/gpu/drm/drm_fbdev_dma.c
+++ b/drivers/gpu/drm/drm_fbdev_dma.c
@@ -130,7 +130,12 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper,
info->flags |= FBINFO_READS_FAST; /* signal caching */
info->screen_size = sizes->surface_height * fb->pitches[0];
info->screen_buffer = map.vaddr;
- info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
+
+ if (is_vmalloc_addr(info->screen_buffer))
+ info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
+ else
+ info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
+
info->fix.smem_len = info->screen_size;
return 0;
--
2.37.1
Hi
Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
> From: Peng Fan <[email protected]>
>
> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
> will not be able to get correct results. With CONFIG_DEBUG_VM and
> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
Which graphics driver triggers this bug?
> [ 3.536043] ------------[ cut here ]------------
> [ 3.540716] virt_to_phys used for non-linear address: 000000007fc4f540 (0xffff800086001000)
> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x68/0x98
> [ 3.565455] Modules linked in:
> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted 6.6.23-06226-g4986cc3e1b75-dirty #250
> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 3.595233] pc : __virt_to_phys+0x68/0x98
> [ 3.599246] lr : __virt_to_phys+0x68/0x98
> [ 3.603276] sp : ffff800083603990
> [ 3.677939] Call trace:
> [ 3.680393] __virt_to_phys+0x68/0x98
> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
> [ 3.705161] drm_client_register+0x60/0xb0
> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>
> So add a check 'is_vmalloc_addr'.
>
> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for GEM DMA helpers")
> Signed-off-by: Peng Fan <[email protected]>
Reviewed-by: Thomas Zimmermann <[email protected]>
Best regards
Thomas
> ---
> drivers/gpu/drm/drm_fbdev_dma.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_fbdev_dma.c b/drivers/gpu/drm/drm_fbdev_dma.c
> index 6c9427bb4053..9e2eddb6eb5c 100644
> --- a/drivers/gpu/drm/drm_fbdev_dma.c
> +++ b/drivers/gpu/drm/drm_fbdev_dma.c
> @@ -130,7 +130,12 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper,
> info->flags |= FBINFO_READS_FAST; /* signal caching */
> info->screen_size = sizes->surface_height * fb->pitches[0];
> info->screen_buffer = map.vaddr;
> - info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
> +
> + if (is_vmalloc_addr(info->screen_buffer))
> + info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
> + else
> + info->fix.smem_start = page_to_phys(virt_to_page(info->screen_buffer));
> +
> info->fix.smem_len = info->screen_size;
>
> return 0;
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>
> Hi
>
> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
> > From: Peng Fan <[email protected]>
> >
> > If 'info->screen_buffer' locates in vmalloc address space,
> > virt_to_page will not be able to get correct results. With
> > CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
> there is dump below:
>
> Which graphics driver triggers this bug?
It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
Thanks,
Peng.
Hi
Am 11.06.24 um 03:00 schrieb Peng Fan:
>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>>
>> Hi
>>
>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>> From: Peng Fan <[email protected]>
>>>
>>> If 'info->screen_buffer' locates in vmalloc address space,
>>> virt_to_page will not be able to get correct results. With
>>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
>> there is dump below:
>>
>> Which graphics driver triggers this bug?
> It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
Which DRM memory manager does that driver use?
I'm asking because if the driver allocates BOs via vmalloc(), should it
really use fbdev-dma?
Best regards
Thomas
>
> Thanks,
> Peng.
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>
> Hi
>
> Am 11.06.24 um 03:00 schrieb Peng Fan:
> >> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
> >>
> >> Hi
> >>
> >> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
> >>> From: Peng Fan <[email protected]>
> >>>
> >>> If 'info->screen_buffer' locates in vmalloc address space,
> >>> virt_to_page will not be able to get correct results. With
> >>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
> >> there is dump below:
> >>
> >> Which graphics driver triggers this bug?
> > It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
>
> Which DRM memory manager does that driver use?
DRM_GEM_DMA_DRIVER_OPS
>
> I'm asking because if the driver allocates BOs via vmalloc(), should it really
> use fbdev-dma?
We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0,
fbdev emulation could be disabled.
Thanks
Peng
>
> Best regards
> Thomas
>
> >
> > Thanks,
> > Peng.
>
> --
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstrasse 146, 90461 Nuernberg, Germany
> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB
> 36809 (AG Nuernberg)
Hi
Am 11.06.24 um 10:23 schrieb Peng Fan:
>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>>
>> Hi
>>
>> Am 11.06.24 um 03:00 schrieb Peng Fan:
>>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>>>>
>>>> Hi
>>>>
>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>>>> From: Peng Fan <[email protected]>
>>>>>
>>>>> If 'info->screen_buffer' locates in vmalloc address space,
>>>>> virt_to_page will not be able to get correct results. With
>>>>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
>>>> there is dump below:
>>>>
>>>> Which graphics driver triggers this bug?
>>> It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
>> Which DRM memory manager does that driver use?
> DRM_GEM_DMA_DRIVER_OPS
So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't
you allocate from one of these dma_alloc_() calls at [1] ? How does the
drivers end up with vmalloc'd fbdev memory? Specifically in the light of
the docs at [2].
[1]
https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146
[2]
https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124
Best regards
Thomas
>
>> I'm asking because if the driver allocates BOs via vmalloc(), should it really
>> use fbdev-dma?
> We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0,
> fbdev emulation could be disabled.
>
> Thanks
> Peng
>> Best regards
>> Thomas
>>
>>> Thanks,
>>> Peng.
>> --
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Frankenstrasse 146, 90461 Nuernberg, Germany
>> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB
>> 36809 (AG Nuernberg)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
Hi
Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
> Hi
>
> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>> From: Peng Fan <[email protected]>
>>
>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
>> will not be able to get correct results. With CONFIG_DEBUG_VM and
>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
>
> Which graphics driver triggers this bug?
>
>> [ 3.536043] ------------[ cut here ]------------
>> [ 3.540716] virt_to_phys used for non-linear address:
>> 000000007fc4f540 (0xffff800086001000)
>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12
>> __virt_to_phys+0x68/0x98
>> [ 3.565455] Modules linked in:
>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
>> 6.6.23-06226-g4986cc3e1b75-dirty #250
>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>> BTYPE=--)
>> [ 3.595233] pc : __virt_to_phys+0x68/0x98
>> [ 3.599246] lr : __virt_to_phys+0x68/0x98
>> [ 3.603276] sp : ffff800083603990
>> [ 3.677939] Call trace:
>> [ 3.680393] __virt_to_phys+0x68/0x98
>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
>> [ 3.705161] drm_client_register+0x60/0xb0
>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>>
>> So add a check 'is_vmalloc_addr'.
>>
>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
>> GEM DMA helpers")
>> Signed-off-by: Peng Fan <[email protected]>
>
> Reviewed-by: Thomas Zimmermann <[email protected]>
I'm taking back my r-b. The memory is expected to by be physically
contiguous and vmalloc() won't guarantee that.
Best regards
Thomas
>
> Best regards
> Thomas
>
>> ---
>> drivers/gpu/drm/drm_fbdev_dma.c | 7 ++++++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/drm_fbdev_dma.c
>> b/drivers/gpu/drm/drm_fbdev_dma.c
>> index 6c9427bb4053..9e2eddb6eb5c 100644
>> --- a/drivers/gpu/drm/drm_fbdev_dma.c
>> +++ b/drivers/gpu/drm/drm_fbdev_dma.c
>> @@ -130,7 +130,12 @@ static int drm_fbdev_dma_helper_fb_probe(struct
>> drm_fb_helper *fb_helper,
>> info->flags |= FBINFO_READS_FAST; /* signal caching */
>> info->screen_size = sizes->surface_height * fb->pitches[0];
>> info->screen_buffer = map.vaddr;
>> - info->fix.smem_start =
>> page_to_phys(virt_to_page(info->screen_buffer));
>> +
>> + if (is_vmalloc_addr(info->screen_buffer))
>> + info->fix.smem_start =
>> page_to_phys(vmalloc_to_page(info->screen_buffer));
>> + else
>> + info->fix.smem_start =
>> page_to_phys(virt_to_page(info->screen_buffer));
>> +
>> info->fix.smem_len = info->screen_size;
>> return 0;
>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
Thomas Zimmermann <[email protected]> writes:
Hello Thomas,
> Hi
>
> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
>> Hi
>>
>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>> From: Peng Fan <[email protected]>
>>>
>>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
>>> will not be able to get correct results. With CONFIG_DEBUG_VM and
>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
>>
>> Which graphics driver triggers this bug?
>>
>>> [ 3.536043] ------------[ cut here ]------------
>>> [ 3.540716] virt_to_phys used for non-linear address:
>>> 000000007fc4f540 (0xffff800086001000)
>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12
>>> __virt_to_phys+0x68/0x98
>>> [ 3.565455] Modules linked in:
>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
>>> 6.6.23-06226-g4986cc3e1b75-dirty #250
>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>>> BTYPE=--)
>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98
>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98
>>> [ 3.603276] sp : ffff800083603990
>>> [ 3.677939] Call trace:
>>> [ 3.680393] __virt_to_phys+0x68/0x98
>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
>>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
>>> [ 3.705161] drm_client_register+0x60/0xb0
>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>>>
>>> So add a check 'is_vmalloc_addr'.
>>>
>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
>>> GEM DMA helpers")
>>> Signed-off-by: Peng Fan <[email protected]>
>>
>> Reviewed-by: Thomas Zimmermann <[email protected]>
>
> I'm taking back my r-b. The memory is expected to by be physically
> contiguous and vmalloc() won't guarantee that.
>
Agreed.
> Best regards
> Thomas
>
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat
Hi Javier
Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas:
> Thomas Zimmermann <[email protected]> writes:
>
> Hello Thomas,
>
>> Hi
>>
>> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
>>> Hi
>>>
>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>>> From: Peng Fan <[email protected]>
>>>>
>>>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
>>>> will not be able to get correct results. With CONFIG_DEBUG_VM and
>>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
>>> Which graphics driver triggers this bug?
>>>
>>>> [ 3.536043] ------------[ cut here ]------------
>>>> [ 3.540716] virt_to_phys used for non-linear address:
>>>> 000000007fc4f540 (0xffff800086001000)
>>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12
>>>> __virt_to_phys+0x68/0x98
>>>> [ 3.565455] Modules linked in:
>>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
>>>> 6.6.23-06226-g4986cc3e1b75-dirty #250
>>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
>>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
>>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>>>> BTYPE=--)
>>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98
>>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98
>>>> [ 3.603276] sp : ffff800083603990
>>>> [ 3.677939] Call trace:
>>>> [ 3.680393] __virt_to_phys+0x68/0x98
>>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
>>>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
>>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
>>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
>>>> [ 3.705161] drm_client_register+0x60/0xb0
>>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>>>>
>>>> So add a check 'is_vmalloc_addr'.
>>>>
>>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
>>>> GEM DMA helpers")
>>>> Signed-off-by: Peng Fan <[email protected]>
>>> Reviewed-by: Thomas Zimmermann <[email protected]>
>> I'm taking back my r-b. The memory is expected to by be physically
>> contiguous and vmalloc() won't guarantee that.
>>
> Agreed.
These smem_ fields are clearly designed for PCI BARs of traditional
graphics cards. So can we even assume contiguous memory for DMA? That
was my assumption, but with IOMMUs it might not be the case. Fbdev-dma
only sets smem_start to support a single old userspace driver. Maybe we
should further restrict usage of this field by making it opt-in for each
driver. Best regards Thomas
>
>> Best regards
>> Thomas
>>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
On Tue, Jun 11, 2024 at 11:29:58AM +0200, Thomas Zimmermann wrote:
> Hi
>
> Am 11.06.24 um 10:23 schrieb Peng Fan:
> > > Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
> > >
> > > Hi
> > >
> > > Am 11.06.24 um 03:00 schrieb Peng Fan:
> > > > > Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
> > > > >
> > > > > Hi
> > > > >
> > > > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
> > > > > > From: Peng Fan <[email protected]>
> > > > > >
> > > > > > If 'info->screen_buffer' locates in vmalloc address space,
> > > > > > virt_to_page will not be able to get correct results. With
> > > > > > CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
> > > > > there is dump below:
> > > > >
> > > > > Which graphics driver triggers this bug?
> > > > It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
> > > Which DRM memory manager does that driver use?
> > DRM_GEM_DMA_DRIVER_OPS
>
> So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't you
> allocate from one of these dma_alloc_() calls at [1] ? How does the drivers
> end up with vmalloc'd fbdev memory? Specifically in the light of the docs at
> [2].
I think when you have an iommu dma_alloc just allocates pages, and uses
the iommu to make it all contiguous for the device, and vmalloc for the
kernel. So it's not allocated with vmalloc(), just ends up getting mapped
into the vmalloc range.
-Sima
>
> [1] https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146
> [2] https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124
>
> Best regards
> Thomas
>
> >
> > > I'm asking because if the driver allocates BOs via vmalloc(), should it really
> > > use fbdev-dma?
> > We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0,
> > fbdev emulation could be disabled.
> >
> > Thanks
> > Peng
> > > Best regards
> > > Thomas
> > >
> > > > Thanks,
> > > > Peng.
> > > --
> > > --
> > > Thomas Zimmermann
> > > Graphics Driver Developer
> > > SUSE Software Solutions Germany GmbH
> > > Frankenstrasse 146, 90461 Nuernberg, Germany
> > > GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB
> > > 36809 (AG Nuernberg)
>
> --
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Frankenstrasse 146, 90461 Nuernberg, Germany
> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
> HRB 36809 (AG Nuernberg)
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
Hi
Am 12.06.24 um 10:45 schrieb Daniel Vetter:
> On Tue, Jun 11, 2024 at 11:29:58AM +0200, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 11.06.24 um 10:23 schrieb Peng Fan:
>>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>>>>
>>>> Hi
>>>>
>>>> Am 11.06.24 um 03:00 schrieb Peng Fan:
>>>>>> Subject: Re: [PATCH] drm/fbdev-dma: fix getting smem_start
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>>>>>> From: Peng Fan <[email protected]>
>>>>>>>
>>>>>>> If 'info->screen_buffer' locates in vmalloc address space,
>>>>>>> virt_to_page will not be able to get correct results. With
>>>>>>> CONFIG_DEBUG_VM and CONFIG_DEBUG_VIRTUAL enabled on ARM64,
>>>>>> there is dump below:
>>>>>>
>>>>>> Which graphics driver triggers this bug?
>>>>> It is NXP i.MX95 DPU driver which is still in NXP downstream repo.
>>>> Which DRM memory manager does that driver use?
>>> DRM_GEM_DMA_DRIVER_OPS
>> So fbdev-dma would be correct. But with the gem-dma allocator, wouldn't you
>> allocate from one of these dma_alloc_() calls at [1] ? How does the drivers
>> end up with vmalloc'd fbdev memory? Specifically in the light of the docs at
>> [2].
> I think when you have an iommu dma_alloc just allocates pages, and uses
> the iommu to make it all contiguous for the device, and vmalloc for the
> kernel. So it's not allocated with vmalloc(), just ends up getting mapped
> into the vmalloc range.
Thanks, that makes sense. As I mentioned in another reply, it might make
sense to protect smem_start with an opt-in flag for only that single
driver that needs it.
Best regards
Thomas
> -Sima
>
>
>> [1] https://elixir.bootlin.com/linux/v6.9/source/drivers/gpu/drm/drm_gem_dma_helper.c#L146
>> [2] https://elixir.bootlin.com/linux/v6.9/source/Documentation/core-api/dma-api-howto.rst#L124
>>
>> Best regards
>> Thomas
>>
>>>> I'm asking because if the driver allocates BOs via vmalloc(), should it really
>>>> use fbdev-dma?
>>> We use it for fbdev emulation. If drm_kms_helper.fbdev_emulation is 0,
>>> fbdev emulation could be disabled.
>>>
>>> Thanks
>>> Peng
>>>> Best regards
>>>> Thomas
>>>>
>>>>> Thanks,
>>>>> Peng.
>>>> --
>>>> --
>>>> Thomas Zimmermann
>>>> Graphics Driver Developer
>>>> SUSE Software Solutions Germany GmbH
>>>> Frankenstrasse 146, 90461 Nuernberg, Germany
>>>> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman HRB
>>>> 36809 (AG Nuernberg)
>> --
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Frankenstrasse 146, 90461 Nuernberg, Germany
>> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
>> HRB 36809 (AG Nuernberg)
>>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote:
> Hi Javier
>
> Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas:
> > Thomas Zimmermann <[email protected]> writes:
> >
> > Hello Thomas,
> >
> > > Hi
> > >
> > > Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
> > > > Hi
> > > >
> > > > Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
> > > > > From: Peng Fan <[email protected]>
> > > > >
> > > > > If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
> > > > > will not be able to get correct results. With CONFIG_DEBUG_VM and
> > > > > CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
> > > > Which graphics driver triggers this bug?
> > > >
> > > > > [??? 3.536043] ------------[ cut here ]------------
> > > > > [??? 3.540716] virt_to_phys used for non-linear address:
> > > > > 000000007fc4f540 (0xffff800086001000)
> > > > > [??? 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12
> > > > > __virt_to_phys+0x68/0x98
> > > > > [??? 3.565455] Modules linked in:
> > > > > [??? 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
> > > > > 6.6.23-06226-g4986cc3e1b75-dirty #250
> > > > > [??? 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
> > > > > [??? 3.582452] Workqueue: events_unbound deferred_probe_work_func
> > > > > [??? 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
> > > > > BTYPE=--)
> > > > > [??? 3.595233] pc : __virt_to_phys+0x68/0x98
> > > > > [??? 3.599246] lr : __virt_to_phys+0x68/0x98
> > > > > [??? 3.603276] sp : ffff800083603990
> > > > > [??? 3.677939] Call trace:
> > > > > [??? 3.680393]? __virt_to_phys+0x68/0x98
> > > > > [??? 3.684067]? drm_fbdev_dma_helper_fb_probe+0x138/0x238
> > > > > [??? 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
> > > > > [??? 3.695385]? drm_fb_helper_initial_config+0x4c/0x68
> > > > > [??? 3.700264]? drm_fbdev_dma_client_hotplug+0x8c/0xe0
> > > > > [??? 3.705161]? drm_client_register+0x60/0xb0
> > > > > [??? 3.709269]? drm_fbdev_dma_setup+0x94/0x148
> > > > >
> > > > > So add a check 'is_vmalloc_addr'.
> > > > >
> > > > > Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
> > > > > GEM DMA helpers")
> > > > > Signed-off-by: Peng Fan <[email protected]>
> > > > Reviewed-by: Thomas Zimmermann <[email protected]>
> > > I'm taking back my r-b. The memory is expected to by be physically
> > > contiguous and vmalloc() won't guarantee that.
> > >
> > Agreed.
>
> These smem_ fields are clearly designed for PCI BARs of traditional graphics
> cards. So can we even assume contiguous memory for DMA? That was my
> assumption, but with IOMMUs it might not be the case. Fbdev-dma only sets
> smem_start to support a single old userspace driver. Maybe we should further
> restrict usage of this field by making it opt-in for each driver. Best
> regards Thomas
We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and
remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is
that with the old fb_mmap code we had to always fill out smem_start to
make mmap work. But now that the various drm fbdev helpers have all their
own mmap implementation, we could make this a lot cleaner.
If I haven't missed anything, that is.
-Sima
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
Hi
Am 13.06.24 um 12:14 schrieb Thomas Zimmermann:
> Hi
>
> Am 12.06.24 um 17:00 schrieb Daniel Vetter:
>> On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote:
>>> Hi Javier
>>>
>>> Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas:
>>>> Thomas Zimmermann <[email protected]> writes:
>>>>
>>>> Hello Thomas,
>>>>
>>>>> Hi
>>>>>
>>>>> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
>>>>>> Hi
>>>>>>
>>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>>>>>> From: Peng Fan <[email protected]>
>>>>>>>
>>>>>>> If 'info->screen_buffer' locates in vmalloc address space,
>>>>>>> virt_to_page
>>>>>>> will not be able to get correct results. With CONFIG_DEBUG_VM and
>>>>>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
>>>>>> Which graphics driver triggers this bug?
>>>>>>
>>>>>>> [ 3.536043] ------------[ cut here ]------------
>>>>>>> [ 3.540716] virt_to_phys used for non-linear address:
>>>>>>> 000000007fc4f540 (0xffff800086001000)
>>>>>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at
>>>>>>> arch/arm64/mm/physaddr.c:12
>>>>>>> __virt_to_phys+0x68/0x98
>>>>>>> [ 3.565455] Modules linked in:
>>>>>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
>>>>>>> 6.6.23-06226-g4986cc3e1b75-dirty #250
>>>>>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
>>>>>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
>>>>>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT
>>>>>>> -SSBS
>>>>>>> BTYPE=--)
>>>>>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98
>>>>>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98
>>>>>>> [ 3.603276] sp : ffff800083603990
>>>>>>> [ 3.677939] Call trace:
>>>>>>> [ 3.680393] __virt_to_phys+0x68/0x98
>>>>>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
>>>>>>> [ 3.689214]
>>>>>>> __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
>>>>>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
>>>>>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
>>>>>>> [ 3.705161] drm_client_register+0x60/0xb0
>>>>>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>>>>>>>
>>>>>>> So add a check 'is_vmalloc_addr'.
>>>>>>>
>>>>>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
>>>>>>> GEM DMA helpers")
>>>>>>> Signed-off-by: Peng Fan <[email protected]>
>>>>>> Reviewed-by: Thomas Zimmermann <[email protected]>
>>>>> I'm taking back my r-b. The memory is expected to by be physically
>>>>> contiguous and vmalloc() won't guarantee that.
>>>>>
>>>> Agreed.
>>> These smem_ fields are clearly designed for PCI BARs of traditional
>>> graphics
>>> cards. So can we even assume contiguous memory for DMA? That was my
>>> assumption, but with IOMMUs it might not be the case. Fbdev-dma only
>>> sets
>>> smem_start to support a single old userspace driver. Maybe we should
>>> further
>>> restrict usage of this field by making it opt-in for each driver. Best
>>> regards Thomas
>> We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and
>> remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is
>> that with the old fb_mmap code we had to always fill out smem_start to
>> make mmap work. But now that the various drm fbdev helpers have all
>> their
>> own mmap implementation, we could make this a lot cleaner.
>
> Enabling CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM would still crash the NXP
> driver. I think I'll add a flag to drm_fbdev_dma_setup() to set
> smem_start from within lima, which is the only driver that requires
> it.I'd like to remove CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and all that,
> but I fear that it would break someone's setup. Best regards Thomas
I've been looking at
https://lore.kernel.org/dri-devel/20240318-dark-mongoose-of-camouflage-7ac6ed@houat/
and I'm now confused to find that lima doesn't even set up fbdev support.
Best regards
Thomas
>>
>> If I haven't missed anything, that is.
>> -Sima
>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
Hi
Am 12.06.24 um 17:00 schrieb Daniel Vetter:
> On Wed, Jun 12, 2024 at 10:37:14AM +0200, Thomas Zimmermann wrote:
>> Hi Javier
>>
>> Am 12.06.24 um 09:49 schrieb Javier Martinez Canillas:
>>> Thomas Zimmermann <[email protected]> writes:
>>>
>>> Hello Thomas,
>>>
>>>> Hi
>>>>
>>>> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
>>>>> Hi
>>>>>
>>>>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>>>>> From: Peng Fan <[email protected]>
>>>>>>
>>>>>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
>>>>>> will not be able to get correct results. With CONFIG_DEBUG_VM and
>>>>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
>>>>> Which graphics driver triggers this bug?
>>>>>
>>>>>> [ 3.536043] ------------[ cut here ]------------
>>>>>> [ 3.540716] virt_to_phys used for non-linear address:
>>>>>> 000000007fc4f540 (0xffff800086001000)
>>>>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12
>>>>>> __virt_to_phys+0x68/0x98
>>>>>> [ 3.565455] Modules linked in:
>>>>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
>>>>>> 6.6.23-06226-g4986cc3e1b75-dirty #250
>>>>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
>>>>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
>>>>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>>>>>> BTYPE=--)
>>>>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98
>>>>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98
>>>>>> [ 3.603276] sp : ffff800083603990
>>>>>> [ 3.677939] Call trace:
>>>>>> [ 3.680393] __virt_to_phys+0x68/0x98
>>>>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
>>>>>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
>>>>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
>>>>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
>>>>>> [ 3.705161] drm_client_register+0x60/0xb0
>>>>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>>>>>>
>>>>>> So add a check 'is_vmalloc_addr'.
>>>>>>
>>>>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
>>>>>> GEM DMA helpers")
>>>>>> Signed-off-by: Peng Fan <[email protected]>
>>>>> Reviewed-by: Thomas Zimmermann <[email protected]>
>>>> I'm taking back my r-b. The memory is expected to by be physically
>>>> contiguous and vmalloc() won't guarantee that.
>>>>
>>> Agreed.
>> These smem_ fields are clearly designed for PCI BARs of traditional graphics
>> cards. So can we even assume contiguous memory for DMA? That was my
>> assumption, but with IOMMUs it might not be the case. Fbdev-dma only sets
>> smem_start to support a single old userspace driver. Maybe we should further
>> restrict usage of this field by making it opt-in for each driver. Best
>> regards Thomas
> We could make it all conditional on CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM, and
> remove the FBINFO_HIDE_SMEM_START flag. The reason I've done the flag is
> that with the old fb_mmap code we had to always fill out smem_start to
> make mmap work. But now that the various drm fbdev helpers have all their
> own mmap implementation, we could make this a lot cleaner.
Enabling CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM would still crash the NXP
driver. I think I'll add a flag to drm_fbdev_dma_setup() to set
smem_start from within lima, which is the only driver that requires
it.I'd like to remove CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM and all that, but
I fear that it would break someone's setup. Best regards Thomas
>
> If I haven't missed anything, that is.
> -Sima
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)