* [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value
@ 2016-09-20 12:41 ` Magnus Damm
0 siblings, 0 replies; 6+ messages in thread
From: Magnus Damm @ 2016-09-20 12:41 UTC (permalink / raw)
To: iommu
Cc: linux-renesas-soc, Magnus Damm, laurent.pinchart+renesas, joro,
geert+renesas
From: Magnus Damm <damm+renesas@opensource.se>
Update the IPMMU driver to return -ENODEV when adding devices
not hooked up a particular IPMMU instance.
Currently the ->add_device() callback implementation in the IPMMU
driver returns -ENODEV for devices with no "iommus" property,
however the function ipmmu_find_utlbs() may return -EINVAL.
This patch updates the ipmmu_find_utlbs() return value to -ENODEV
for the case when multiple IPMMU instances exist. That way the
code matches the expected behaviour described in the comment of
the add_iommu_group() function in iommu.c:
/*
* We ignore -ENODEV errors for now, as they just mean that the
* device is not translated by an IOMMU. We still care about
* other errors and fail to initialize when they happen.
*/
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
---
Applies to next-20160920 on top of:
b1e2afc iommu/ipmmu-vmsa: Fix wrong error handle of ipmmu_add_device
drivers/iommu/ipmmu-vmsa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 0002/drivers/iommu/ipmmu-vmsa.c
+++ work/drivers/iommu/ipmmu-vmsa.c 2016-09-08 18:20:06.270607110 +0900
@@ -781,7 +781,7 @@ static int ipmmu_find_utlbs(struct ipmmu
of_node_put(args.np);
if (args.np != mmu->dev->of_node || args.args_count != 1)
- return -EINVAL;
+ return -ENODEV;
utlbs[i] = args.args[0];
}
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value
@ 2016-09-20 12:41 ` Magnus Damm
0 siblings, 0 replies; 6+ messages in thread
From: Magnus Damm @ 2016-09-20 12:41 UTC (permalink / raw)
To: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA
Cc: linux-renesas-soc-u79uwXL29TY76Z2rM5mHXA,
laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw, Magnus Damm,
geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ
From: Magnus Damm <damm+renesas-yzvPICuk2ACczHhG9Qg4qA@public.gmane.org>
Update the IPMMU driver to return -ENODEV when adding devices
not hooked up a particular IPMMU instance.
Currently the ->add_device() callback implementation in the IPMMU
driver returns -ENODEV for devices with no "iommus" property,
however the function ipmmu_find_utlbs() may return -EINVAL.
This patch updates the ipmmu_find_utlbs() return value to -ENODEV
for the case when multiple IPMMU instances exist. That way the
code matches the expected behaviour described in the comment of
the add_iommu_group() function in iommu.c:
/*
* We ignore -ENODEV errors for now, as they just mean that the
* device is not translated by an IOMMU. We still care about
* other errors and fail to initialize when they happen.
*/
Signed-off-by: Magnus Damm <damm+renesas-yzvPICuk2ACczHhG9Qg4qA@public.gmane.org>
---
Applies to next-20160920 on top of:
b1e2afc iommu/ipmmu-vmsa: Fix wrong error handle of ipmmu_add_device
drivers/iommu/ipmmu-vmsa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 0002/drivers/iommu/ipmmu-vmsa.c
+++ work/drivers/iommu/ipmmu-vmsa.c 2016-09-08 18:20:06.270607110 +0900
@@ -781,7 +781,7 @@ static int ipmmu_find_utlbs(struct ipmmu
of_node_put(args.np);
if (args.np != mmu->dev->of_node || args.args_count != 1)
- return -EINVAL;
+ return -ENODEV;
utlbs[i] = args.args[0];
}
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value
2016-09-20 12:41 ` Magnus Damm
@ 2016-09-20 13:18 ` Robin Murphy
-1 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2016-09-20 13:18 UTC (permalink / raw)
To: Magnus Damm, iommu
Cc: linux-renesas-soc, laurent.pinchart+renesas, geert+renesas
Hi Magnus,
On 20/09/16 13:41, Magnus Damm wrote:
> From: Magnus Damm <damm+renesas@opensource.se>
>
> Update the IPMMU driver to return -ENODEV when adding devices
> not hooked up a particular IPMMU instance.
>
> Currently the ->add_device() callback implementation in the IPMMU
> driver returns -ENODEV for devices with no "iommus" property,
> however the function ipmmu_find_utlbs() may return -EINVAL.
If there were no "iommus" property at all, of_parse_phandle_with_args()
should return -ENOENT - that probably does want to be caught and passed
back as -ENODEV to imply an untranslated device. On the other hand,
-EINVAL would stem from the existence of the property, but in a somehow
erroneous manner - other than the "args.np != mmu->dev->of_node" check
(which could legitimately fail and be safely ignored if there are
multiple IOMMUs in the system), any other reason implies a DT error
which probably shouldn't be papered over.
Robin.
> This patch updates the ipmmu_find_utlbs() return value to -ENODEV
> for the case when multiple IPMMU instances exist. That way the
> code matches the expected behaviour described in the comment of
> the add_iommu_group() function in iommu.c:
>
> /*
> * We ignore -ENODEV errors for now, as they just mean that the
> * device is not translated by an IOMMU. We still care about
> * other errors and fail to initialize when they happen.
> */
>
> Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
> ---
>
> Applies to next-20160920 on top of:
> b1e2afc iommu/ipmmu-vmsa: Fix wrong error handle of ipmmu_add_device
>
> drivers/iommu/ipmmu-vmsa.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- 0002/drivers/iommu/ipmmu-vmsa.c
> +++ work/drivers/iommu/ipmmu-vmsa.c 2016-09-08 18:20:06.270607110 +0900
> @@ -781,7 +781,7 @@ static int ipmmu_find_utlbs(struct ipmmu
> of_node_put(args.np);
>
> if (args.np != mmu->dev->of_node || args.args_count != 1)
> - return -EINVAL;
> + return -ENODEV;
>
> utlbs[i] = args.args[0];
> }
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value
@ 2016-09-20 13:18 ` Robin Murphy
0 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2016-09-20 13:18 UTC (permalink / raw)
To: Magnus Damm, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA
Cc: linux-renesas-soc-u79uwXL29TY76Z2rM5mHXA,
laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw,
geert+renesas-gXvu3+zWzMSzQB+pC5nmwQ
Hi Magnus,
On 20/09/16 13:41, Magnus Damm wrote:
> From: Magnus Damm <damm+renesas-yzvPICuk2ACczHhG9Qg4qA@public.gmane.org>
>
> Update the IPMMU driver to return -ENODEV when adding devices
> not hooked up a particular IPMMU instance.
>
> Currently the ->add_device() callback implementation in the IPMMU
> driver returns -ENODEV for devices with no "iommus" property,
> however the function ipmmu_find_utlbs() may return -EINVAL.
If there were no "iommus" property at all, of_parse_phandle_with_args()
should return -ENOENT - that probably does want to be caught and passed
back as -ENODEV to imply an untranslated device. On the other hand,
-EINVAL would stem from the existence of the property, but in a somehow
erroneous manner - other than the "args.np != mmu->dev->of_node" check
(which could legitimately fail and be safely ignored if there are
multiple IOMMUs in the system), any other reason implies a DT error
which probably shouldn't be papered over.
Robin.
> This patch updates the ipmmu_find_utlbs() return value to -ENODEV
> for the case when multiple IPMMU instances exist. That way the
> code matches the expected behaviour described in the comment of
> the add_iommu_group() function in iommu.c:
>
> /*
> * We ignore -ENODEV errors for now, as they just mean that the
> * device is not translated by an IOMMU. We still care about
> * other errors and fail to initialize when they happen.
> */
>
> Signed-off-by: Magnus Damm <damm+renesas-yzvPICuk2ACczHhG9Qg4qA@public.gmane.org>
> ---
>
> Applies to next-20160920 on top of:
> b1e2afc iommu/ipmmu-vmsa: Fix wrong error handle of ipmmu_add_device
>
> drivers/iommu/ipmmu-vmsa.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- 0002/drivers/iommu/ipmmu-vmsa.c
> +++ work/drivers/iommu/ipmmu-vmsa.c 2016-09-08 18:20:06.270607110 +0900
> @@ -781,7 +781,7 @@ static int ipmmu_find_utlbs(struct ipmmu
> of_node_put(args.np);
>
> if (args.np != mmu->dev->of_node || args.args_count != 1)
> - return -EINVAL;
> + return -ENODEV;
>
> utlbs[i] = args.args[0];
> }
> _______________________________________________
> iommu mailing list
> iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value
2016-09-20 13:18 ` Robin Murphy
(?)
@ 2016-09-20 15:03 ` Magnus Damm
2016-09-22 15:56 ` Robin Murphy
-1 siblings, 1 reply; 6+ messages in thread
From: Magnus Damm @ 2016-09-20 15:03 UTC (permalink / raw)
To: Robin Murphy; +Cc: iommu, Linux-Renesas, Laurent Pinchart, Geert Uytterhoeven
Hi Robin,
Thanks for your feedback!!
On Tue, Sep 20, 2016 at 10:18 PM, Robin Murphy <robin.murphy@arm.com> wrote:
> Hi Magnus,
>
> On 20/09/16 13:41, Magnus Damm wrote:
>> From: Magnus Damm <damm+renesas@opensource.se>
>>
>> Update the IPMMU driver to return -ENODEV when adding devices
>> not hooked up a particular IPMMU instance.
>>
>> Currently the ->add_device() callback implementation in the IPMMU
>> driver returns -ENODEV for devices with no "iommus" property,
>> however the function ipmmu_find_utlbs() may return -EINVAL.
>
> If there were no "iommus" property at all, of_parse_phandle_with_args()
> should return -ENOENT - that probably does want to be caught and passed
> back as -ENODEV to imply an untranslated device. On the other hand,
> -EINVAL would stem from the existence of the property, but in a somehow
> erroneous manner - other than the "args.np != mmu->dev->of_node" check
> (which could legitimately fail and be safely ignored if there are
> multiple IOMMUs in the system), any other reason implies a DT error
> which probably shouldn't be papered over.
Regarding -ENOENT to -ENODEV, I agree but I believe this case is
already handled. The ->add_device() callback seems to be using
of_count_phandle_with_args() to check for the presence of "iommus"
property before calling ipmmu_find_utlbs(). So for the case with no
"iommus" property at all it is returned as -ENODEV as you suggest.
The ->add_device() callback has the ret variable initialised to
-ENODEV by default. In case there is only one IPMMU device on the
ipmmu_device list and it matches the struct device passed to the
ipmmu_add_device() function then all is fine. However when there are
more than one IPMMU device on the ipmmu_device list then
ipmmu_find_utlbs() may return -EINVAL. Judging by the code this seems
to happen when the order of the IPMMU devices on the "iommus" property
does not match the IPMMU order on the ipmmu_device list.
Hm, I wonder if all this should be replaced with ->xlate() somehow?
Thanks,
/ magnus
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value
2016-09-20 15:03 ` Magnus Damm
@ 2016-09-22 15:56 ` Robin Murphy
0 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2016-09-22 15:56 UTC (permalink / raw)
To: Magnus Damm; +Cc: iommu, Linux-Renesas, Laurent Pinchart, Geert Uytterhoeven
On 20/09/16 16:03, Magnus Damm wrote:
> Hi Robin,
>
> Thanks for your feedback!!
>
> On Tue, Sep 20, 2016 at 10:18 PM, Robin Murphy <robin.murphy@arm.com> wrote:
>> Hi Magnus,
>>
>> On 20/09/16 13:41, Magnus Damm wrote:
>>> From: Magnus Damm <damm+renesas@opensource.se>
>>>
>>> Update the IPMMU driver to return -ENODEV when adding devices
>>> not hooked up a particular IPMMU instance.
>>>
>>> Currently the ->add_device() callback implementation in the IPMMU
>>> driver returns -ENODEV for devices with no "iommus" property,
>>> however the function ipmmu_find_utlbs() may return -EINVAL.
>>
>> If there were no "iommus" property at all, of_parse_phandle_with_args()
>> should return -ENOENT - that probably does want to be caught and passed
>> back as -ENODEV to imply an untranslated device. On the other hand,
>> -EINVAL would stem from the existence of the property, but in a somehow
>> erroneous manner - other than the "args.np != mmu->dev->of_node" check
>> (which could legitimately fail and be safely ignored if there are
>> multiple IOMMUs in the system), any other reason implies a DT error
>> which probably shouldn't be papered over.
>
> Regarding -ENOENT to -ENODEV, I agree but I believe this case is
> already handled. The ->add_device() callback seems to be using
> of_count_phandle_with_args() to check for the presence of "iommus"
> property before calling ipmmu_find_utlbs(). So for the case with no
> "iommus" property at all it is returned as -ENODEV as you suggest.
Ah, right you are, I missed that there was a separate check earlier.
> The ->add_device() callback has the ret variable initialised to
> -ENODEV by default. In case there is only one IPMMU device on the
> ipmmu_device list and it matches the struct device passed to the
> ipmmu_add_device() function then all is fine. However when there are
> more than one IPMMU device on the ipmmu_device list then
> ipmmu_find_utlbs() may return -EINVAL. Judging by the code this seems
> to happen when the order of the IPMMU devices on the "iommus" property
> does not match the IPMMU order on the ipmmu_device list.
>
> Hm, I wonder if all this should be replaced with ->xlate() somehow?
Ideally, yes - the core code already has most of this covered, so taking
advantage of it would be good. I think the only slight hiccup is that
the 32-bit DMA code is then going to call attach_dev() with a domain you
probably don't want, before you get your add_device() call. Other than
handling that vs. group-based default domains for 64-bit, though, there
shouldn't be anything else to special-case, I don't think.
I'm finally starting to have a look into converting the arch/arm code
over to use groups and default domains sensibly, but I suspect that's
ultimately going to have some dependency on the probe deferral stuff,
rather than introduce the same bus notifier bodge we currently have on
arm64.
Robin.
>
> Thanks,
>
> / magnus
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-09-22 15:56 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2016-09-20 12:41 [PATCH/RFC] iommu/ipmmu-vmsa: Update ->add_device() return value Magnus Damm
2016-09-20 12:41 ` Magnus Damm
2016-09-20 13:18 ` Robin Murphy
2016-09-20 13:18 ` Robin Murphy
2016-09-20 15:03 ` Magnus Damm
2016-09-22 15:56 ` Robin Murphy
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