* RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
@ 2021-02-12 14:54 Shameerali Kolothum Thodi
2021-02-12 16:38 ` Robin Murphy
0 siblings, 1 reply; 6+ messages in thread
From: Shameerali Kolothum Thodi @ 2021-02-12 14:54 UTC (permalink / raw)
To: linux-kernel, iommu
Cc: joro, robin.murphy, jean-philippe, will, Zengtao (B), linuxarm
Hi Robin/Joerg,
> -----Original Message-----
> From: Shameer Kolothum [mailto:shameerali.kolothum.thodi@huawei.com]
> Sent: 01 February 2021 12:41
> To: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
> Cc: joro@8bytes.org; robin.murphy@arm.com; jean-philippe@linaro.org;
> will@kernel.org; Zengtao (B) <prime.zeng@hisilicon.com>;
> linuxarm@openeuler.org
> Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx
> functions
>
> The device iommu probe/attach might have failed leaving dev->iommu
> to NULL and device drivers may still invoke these functions resulting
> in a crash in iommu vendor driver code. Hence make sure we check that.
>
> Also added iommu_ops to the "struct dev_iommu" and set it if the dev
> is successfully associated with an iommu.
>
> Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device")
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
> v1 --> v2:
> -Added iommu_ops to struct dev_iommu based on the discussion with Robin.
> -Rebased against iommu-tree core branch.
A gentle ping on this...
Thanks,
Shameer
> ---
> drivers/iommu/iommu.c | 19 +++++++------------
> include/linux/iommu.h | 2 ++
> 2 files changed, 9 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index fd76e2f579fe..6023d0b7c542 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -217,6 +217,7 @@ static int __iommu_probe_device(struct device *dev,
> struct list_head *group_list
> }
>
> dev->iommu->iommu_dev = iommu_dev;
> + dev->iommu->ops = iommu_dev->ops;
>
> group = iommu_group_get_for_dev(dev);
> if (IS_ERR(group)) {
> @@ -2865,10 +2866,8 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
> */
> int iommu_dev_enable_feature(struct device *dev, enum
> iommu_dev_features feat)
> {
> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> -
> - if (ops && ops->dev_enable_feat)
> - return ops->dev_enable_feat(dev, feat);
> + if (dev->iommu && dev->iommu->ops->dev_enable_feat)
> + return dev->iommu->ops->dev_enable_feat(dev, feat);
>
> return -ENODEV;
> }
> @@ -2881,10 +2880,8 @@
> EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
> */
> int iommu_dev_disable_feature(struct device *dev, enum
> iommu_dev_features feat)
> {
> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> -
> - if (ops && ops->dev_disable_feat)
> - return ops->dev_disable_feat(dev, feat);
> + if (dev->iommu && dev->iommu->ops->dev_disable_feat)
> + return dev->iommu->ops->dev_disable_feat(dev, feat);
>
> return -EBUSY;
> }
> @@ -2892,10 +2889,8 @@
> EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
>
> bool iommu_dev_feature_enabled(struct device *dev, enum
> iommu_dev_features feat)
> {
> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> -
> - if (ops && ops->dev_feat_enabled)
> - return ops->dev_feat_enabled(dev, feat);
> + if (dev->iommu && dev->iommu->ops->dev_feat_enabled)
> + return dev->iommu->ops->dev_feat_enabled(dev, feat);
>
> return false;
> }
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 524ffc2ff64f..ff0c76bdfb67 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -354,6 +354,7 @@ struct iommu_fault_param {
> * @fault_param: IOMMU detected device fault reporting data
> * @fwspec: IOMMU fwspec data
> * @iommu_dev: IOMMU device this device is linked to
> + * @ops: iommu-ops for talking to the iommu_dev
> * @priv: IOMMU Driver private data
> *
> * TODO: migrate other per device data pointers under iommu_dev_data,
> e.g.
> @@ -364,6 +365,7 @@ struct dev_iommu {
> struct iommu_fault_param *fault_param;
> struct iommu_fwspec *fwspec;
> struct iommu_device *iommu_dev;
> + const struct iommu_ops *ops;
> void *priv;
> };
>
> --
> 2.17.1
> _______________________________________________
> Linuxarm mailing list -- linuxarm@openeuler.org
> To unsubscribe send an email to linuxarm-leave@openeuler.org
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
2021-02-12 14:54 [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions Shameerali Kolothum Thodi
@ 2021-02-12 16:38 ` Robin Murphy
2021-02-12 16:44 ` Shameerali Kolothum Thodi
2021-02-12 17:28 ` Shameerali Kolothum Thodi
0 siblings, 2 replies; 6+ messages in thread
From: Robin Murphy @ 2021-02-12 16:38 UTC (permalink / raw)
To: Shameerali Kolothum Thodi, linux-kernel, iommu
Cc: joro, jean-philippe, will, Zengtao (B), linuxarm
On 2021-02-12 14:54, Shameerali Kolothum Thodi wrote:
> Hi Robin/Joerg,
>
>> -----Original Message-----
>> From: Shameer Kolothum [mailto:shameerali.kolothum.thodi@huawei.com]
>> Sent: 01 February 2021 12:41
>> To: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
>> Cc: joro@8bytes.org; robin.murphy@arm.com; jean-philippe@linaro.org;
>> will@kernel.org; Zengtao (B) <prime.zeng@hisilicon.com>;
>> linuxarm@openeuler.org
>> Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx
>> functions
>>
>> The device iommu probe/attach might have failed leaving dev->iommu
>> to NULL and device drivers may still invoke these functions resulting
>> in a crash in iommu vendor driver code. Hence make sure we check that.
>>
>> Also added iommu_ops to the "struct dev_iommu" and set it if the dev
>> is successfully associated with an iommu.
>>
>> Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device")
>> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
>> ---
>> v1 --> v2:
>> -Added iommu_ops to struct dev_iommu based on the discussion with Robin.
>> -Rebased against iommu-tree core branch.
>
> A gentle ping on this...
Is there a convincing justification for maintaining yet another copy of
the ops pointer rather than simply dereferencing iommu_dev->ops at point
of use?
Robin.
> Thanks,
> Shameer
>
>> ---
>> drivers/iommu/iommu.c | 19 +++++++------------
>> include/linux/iommu.h | 2 ++
>> 2 files changed, 9 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index fd76e2f579fe..6023d0b7c542 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -217,6 +217,7 @@ static int __iommu_probe_device(struct device *dev,
>> struct list_head *group_list
>> }
>>
>> dev->iommu->iommu_dev = iommu_dev;
>> + dev->iommu->ops = iommu_dev->ops;
>>
>> group = iommu_group_get_for_dev(dev);
>> if (IS_ERR(group)) {
>> @@ -2865,10 +2866,8 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
>> */
>> int iommu_dev_enable_feature(struct device *dev, enum
>> iommu_dev_features feat)
>> {
>> - const struct iommu_ops *ops = dev->bus->iommu_ops;
>> -
>> - if (ops && ops->dev_enable_feat)
>> - return ops->dev_enable_feat(dev, feat);
>> + if (dev->iommu && dev->iommu->ops->dev_enable_feat)
>> + return dev->iommu->ops->dev_enable_feat(dev, feat);
>>
>> return -ENODEV;
>> }
>> @@ -2881,10 +2880,8 @@
>> EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
>> */
>> int iommu_dev_disable_feature(struct device *dev, enum
>> iommu_dev_features feat)
>> {
>> - const struct iommu_ops *ops = dev->bus->iommu_ops;
>> -
>> - if (ops && ops->dev_disable_feat)
>> - return ops->dev_disable_feat(dev, feat);
>> + if (dev->iommu && dev->iommu->ops->dev_disable_feat)
>> + return dev->iommu->ops->dev_disable_feat(dev, feat);
>>
>> return -EBUSY;
>> }
>> @@ -2892,10 +2889,8 @@
>> EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
>>
>> bool iommu_dev_feature_enabled(struct device *dev, enum
>> iommu_dev_features feat)
>> {
>> - const struct iommu_ops *ops = dev->bus->iommu_ops;
>> -
>> - if (ops && ops->dev_feat_enabled)
>> - return ops->dev_feat_enabled(dev, feat);
>> + if (dev->iommu && dev->iommu->ops->dev_feat_enabled)
>> + return dev->iommu->ops->dev_feat_enabled(dev, feat);
>>
>> return false;
>> }
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 524ffc2ff64f..ff0c76bdfb67 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -354,6 +354,7 @@ struct iommu_fault_param {
>> * @fault_param: IOMMU detected device fault reporting data
>> * @fwspec: IOMMU fwspec data
>> * @iommu_dev: IOMMU device this device is linked to
>> + * @ops: iommu-ops for talking to the iommu_dev
>> * @priv: IOMMU Driver private data
>> *
>> * TODO: migrate other per device data pointers under iommu_dev_data,
>> e.g.
>> @@ -364,6 +365,7 @@ struct dev_iommu {
>> struct iommu_fault_param *fault_param;
>> struct iommu_fwspec *fwspec;
>> struct iommu_device *iommu_dev;
>> + const struct iommu_ops *ops;
>> void *priv;
>> };
>>
>> --
>> 2.17.1
>> _______________________________________________
>> Linuxarm mailing list -- linuxarm@openeuler.org
>> To unsubscribe send an email to linuxarm-leave@openeuler.org
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
2021-02-12 16:38 ` Robin Murphy
@ 2021-02-12 16:44 ` Shameerali Kolothum Thodi
2021-02-12 17:28 ` Shameerali Kolothum Thodi
1 sibling, 0 replies; 6+ messages in thread
From: Shameerali Kolothum Thodi @ 2021-02-12 16:44 UTC (permalink / raw)
To: Robin Murphy, linux-kernel, iommu
Cc: joro, jean-philippe, will, Zengtao (B), linuxarm
> -----Original Message-----
> From: Robin Murphy [mailto:robin.murphy@arm.com]
> Sent: 12 February 2021 16:39
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
> Cc: joro@8bytes.org; jean-philippe@linaro.org; will@kernel.org; Zengtao (B)
> <prime.zeng@hisilicon.com>; linuxarm@openeuler.org
> Subject: Re: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
>
> On 2021-02-12 14:54, Shameerali Kolothum Thodi wrote:
> > Hi Robin/Joerg,
> >
> >> -----Original Message-----
> >> From: Shameer Kolothum [mailto:shameerali.kolothum.thodi@huawei.com]
> >> Sent: 01 February 2021 12:41
> >> To: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
> >> Cc: joro@8bytes.org; robin.murphy@arm.com; jean-philippe@linaro.org;
> >> will@kernel.org; Zengtao (B) <prime.zeng@hisilicon.com>;
> >> linuxarm@openeuler.org
> >> Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in
> iommu_dev_xxx
> >> functions
> >>
> >> The device iommu probe/attach might have failed leaving dev->iommu
> >> to NULL and device drivers may still invoke these functions resulting
> >> in a crash in iommu vendor driver code. Hence make sure we check that.
> >>
> >> Also added iommu_ops to the "struct dev_iommu" and set it if the dev
> >> is successfully associated with an iommu.
> >>
> >> Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device")
> >> Signed-off-by: Shameer Kolothum
> <shameerali.kolothum.thodi@huawei.com>
> >> ---
> >> v1 --> v2:
> >> -Added iommu_ops to struct dev_iommu based on the discussion with
> Robin.
> >> -Rebased against iommu-tree core branch.
> >
> > A gentle ping on this...
>
> Is there a convincing justification for maintaining yet another copy of
> the ops pointer rather than simply dereferencing iommu_dev->ops at point
> of use?
>
TBH, nothing I can think of now. That was mainly the way I interpreted your suggestion
from the v1. Now it looks like you didn’t mean it :). I am Ok to rework it to dereference
it from iommu_dev. Please let me know.
Thanks,
Shameer
> Robin.
>
> > Thanks,
> > Shameer
> >
> >> ---
> >> drivers/iommu/iommu.c | 19 +++++++------------
> >> include/linux/iommu.h | 2 ++
> >> 2 files changed, 9 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> >> index fd76e2f579fe..6023d0b7c542 100644
> >> --- a/drivers/iommu/iommu.c
> >> +++ b/drivers/iommu/iommu.c
> >> @@ -217,6 +217,7 @@ static int __iommu_probe_device(struct device
> *dev,
> >> struct list_head *group_list
> >> }
> >>
> >> dev->iommu->iommu_dev = iommu_dev;
> >> + dev->iommu->ops = iommu_dev->ops;
> >>
> >> group = iommu_group_get_for_dev(dev);
> >> if (IS_ERR(group)) {
> >> @@ -2865,10 +2866,8 @@
> EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
> >> */
> >> int iommu_dev_enable_feature(struct device *dev, enum
> >> iommu_dev_features feat)
> >> {
> >> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> >> -
> >> - if (ops && ops->dev_enable_feat)
> >> - return ops->dev_enable_feat(dev, feat);
> >> + if (dev->iommu && dev->iommu->ops->dev_enable_feat)
> >> + return dev->iommu->ops->dev_enable_feat(dev, feat);
> >>
> >> return -ENODEV;
> >> }
> >> @@ -2881,10 +2880,8 @@
> >> EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
> >> */
> >> int iommu_dev_disable_feature(struct device *dev, enum
> >> iommu_dev_features feat)
> >> {
> >> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> >> -
> >> - if (ops && ops->dev_disable_feat)
> >> - return ops->dev_disable_feat(dev, feat);
> >> + if (dev->iommu && dev->iommu->ops->dev_disable_feat)
> >> + return dev->iommu->ops->dev_disable_feat(dev, feat);
> >>
> >> return -EBUSY;
> >> }
> >> @@ -2892,10 +2889,8 @@
> >> EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
> >>
> >> bool iommu_dev_feature_enabled(struct device *dev, enum
> >> iommu_dev_features feat)
> >> {
> >> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> >> -
> >> - if (ops && ops->dev_feat_enabled)
> >> - return ops->dev_feat_enabled(dev, feat);
> >> + if (dev->iommu && dev->iommu->ops->dev_feat_enabled)
> >> + return dev->iommu->ops->dev_feat_enabled(dev, feat);
> >>
> >> return false;
> >> }
> >> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> >> index 524ffc2ff64f..ff0c76bdfb67 100644
> >> --- a/include/linux/iommu.h
> >> +++ b/include/linux/iommu.h
> >> @@ -354,6 +354,7 @@ struct iommu_fault_param {
> >> * @fault_param: IOMMU detected device fault reporting data
> >> * @fwspec: IOMMU fwspec data
> >> * @iommu_dev: IOMMU device this device is linked to
> >> + * @ops: iommu-ops for talking to the iommu_dev
> >> * @priv: IOMMU Driver private data
> >> *
> >> * TODO: migrate other per device data pointers under
> iommu_dev_data,
> >> e.g.
> >> @@ -364,6 +365,7 @@ struct dev_iommu {
> >> struct iommu_fault_param *fault_param;
> >> struct iommu_fwspec *fwspec;
> >> struct iommu_device *iommu_dev;
> >> + const struct iommu_ops *ops;
> >> void *priv;
> >> };
> >>
> >> --
> >> 2.17.1
> >> _______________________________________________
> >> Linuxarm mailing list -- linuxarm@openeuler.org
> >> To unsubscribe send an email to linuxarm-leave@openeuler.org
^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
2021-02-12 16:38 ` Robin Murphy
2021-02-12 16:44 ` Shameerali Kolothum Thodi
@ 2021-02-12 17:28 ` Shameerali Kolothum Thodi
2021-02-16 13:45 ` Robin Murphy
1 sibling, 1 reply; 6+ messages in thread
From: Shameerali Kolothum Thodi @ 2021-02-12 17:28 UTC (permalink / raw)
To: Robin Murphy, linux-kernel, iommu
Cc: joro, jean-philippe, will, Zengtao (B), linuxarm
> -----Original Message-----
> From: Shameerali Kolothum Thodi
> Sent: 12 February 2021 16:45
> To: 'Robin Murphy' <robin.murphy@arm.com>; linux-kernel@vger.kernel.org;
> iommu@lists.linux-foundation.org
> Cc: joro@8bytes.org; jean-philippe@linaro.org; will@kernel.org; Zengtao (B)
> <prime.zeng@hisilicon.com>; linuxarm@openeuler.org
> Subject: RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
>
>
>
> > -----Original Message-----
> > From: Robin Murphy [mailto:robin.murphy@arm.com]
> > Sent: 12 February 2021 16:39
> > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
> > linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
> > Cc: joro@8bytes.org; jean-philippe@linaro.org; will@kernel.org; Zengtao (B)
> > <prime.zeng@hisilicon.com>; linuxarm@openeuler.org
> > Subject: Re: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx
> functions
> >
> > On 2021-02-12 14:54, Shameerali Kolothum Thodi wrote:
> > > Hi Robin/Joerg,
> > >
> > >> -----Original Message-----
> > >> From: Shameer Kolothum
> [mailto:shameerali.kolothum.thodi@huawei.com]
> > >> Sent: 01 February 2021 12:41
> > >> To: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
> > >> Cc: joro@8bytes.org; robin.murphy@arm.com; jean-philippe@linaro.org;
> > >> will@kernel.org; Zengtao (B) <prime.zeng@hisilicon.com>;
> > >> linuxarm@openeuler.org
> > >> Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in
> > iommu_dev_xxx
> > >> functions
> > >>
> > >> The device iommu probe/attach might have failed leaving dev->iommu
> > >> to NULL and device drivers may still invoke these functions resulting
> > >> in a crash in iommu vendor driver code. Hence make sure we check that.
> > >>
> > >> Also added iommu_ops to the "struct dev_iommu" and set it if the dev
> > >> is successfully associated with an iommu.
> > >>
> > >> Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per
> device")
> > >> Signed-off-by: Shameer Kolothum
> > <shameerali.kolothum.thodi@huawei.com>
> > >> ---
> > >> v1 --> v2:
> > >> -Added iommu_ops to struct dev_iommu based on the discussion with
> > Robin.
> > >> -Rebased against iommu-tree core branch.
> > >
> > > A gentle ping on this...
> >
> > Is there a convincing justification for maintaining yet another copy of
> > the ops pointer rather than simply dereferencing iommu_dev->ops at point
> > of use?
> >
>
> TBH, nothing I can think of now. That was mainly the way I interpreted your
> suggestion
> from the v1. Now it looks like you didn’t mean it :). I am Ok to rework it to
> dereference
> it from iommu_dev. Please let me know.
So we can do something like this,
index fd76e2f579fe..5fd31a3cec18 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2865,10 +2865,12 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
*/
int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
{
- const struct iommu_ops *ops = dev->bus->iommu_ops;
+ if (dev->iommu && dev->iommu->iommu_dev && dev->iommu->iommu_dev->ops)
+ struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
- if (ops && ops->dev_enable_feat)
- return ops->dev_enable_feat(dev, feat);
+ if (ops->dev_enable_feat)
+ return ops->dev_enable_feat(dev, feat);
+ }
return -ENODEV;
}
Again, not sure we need to do the checking for iommu->dev and ops here. If the
dev->iommu is set, is it safe to assume that we have a valid iommu->iommu_dev
and ops always? (May be it is safer to do the checking in case something
else breaks this assumption in future). Please let me know your thoughts.
Thanks,
Shameer
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
2021-02-12 17:28 ` Shameerali Kolothum Thodi
@ 2021-02-16 13:45 ` Robin Murphy
0 siblings, 0 replies; 6+ messages in thread
From: Robin Murphy @ 2021-02-16 13:45 UTC (permalink / raw)
To: Shameerali Kolothum Thodi, linux-kernel, iommu
Cc: jean-philippe, will, linuxarm, Zengtao (B)
On 2021-02-12 17:28, Shameerali Kolothum Thodi wrote:
>
>
>> -----Original Message-----
>> From: Shameerali Kolothum Thodi
>> Sent: 12 February 2021 16:45
>> To: 'Robin Murphy' <robin.murphy@arm.com>; linux-kernel@vger.kernel.org;
>> iommu@lists.linux-foundation.org
>> Cc: joro@8bytes.org; jean-philippe@linaro.org; will@kernel.org; Zengtao (B)
>> <prime.zeng@hisilicon.com>; linuxarm@openeuler.org
>> Subject: RE: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
>>
>>
>>
>>> -----Original Message-----
>>> From: Robin Murphy [mailto:robin.murphy@arm.com]
>>> Sent: 12 February 2021 16:39
>>> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>;
>>> linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
>>> Cc: joro@8bytes.org; jean-philippe@linaro.org; will@kernel.org; Zengtao (B)
>>> <prime.zeng@hisilicon.com>; linuxarm@openeuler.org
>>> Subject: Re: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx
>> functions
>>>
>>> On 2021-02-12 14:54, Shameerali Kolothum Thodi wrote:
>>>> Hi Robin/Joerg,
>>>>
>>>>> -----Original Message-----
>>>>> From: Shameer Kolothum
>> [mailto:shameerali.kolothum.thodi@huawei.com]
>>>>> Sent: 01 February 2021 12:41
>>>>> To: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org
>>>>> Cc: joro@8bytes.org; robin.murphy@arm.com; jean-philippe@linaro.org;
>>>>> will@kernel.org; Zengtao (B) <prime.zeng@hisilicon.com>;
>>>>> linuxarm@openeuler.org
>>>>> Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in
>>> iommu_dev_xxx
>>>>> functions
>>>>>
>>>>> The device iommu probe/attach might have failed leaving dev->iommu
>>>>> to NULL and device drivers may still invoke these functions resulting
>>>>> in a crash in iommu vendor driver code. Hence make sure we check that.
>>>>>
>>>>> Also added iommu_ops to the "struct dev_iommu" and set it if the dev
>>>>> is successfully associated with an iommu.
>>>>>
>>>>> Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per
>> device")
>>>>> Signed-off-by: Shameer Kolothum
>>> <shameerali.kolothum.thodi@huawei.com>
>>>>> ---
>>>>> v1 --> v2:
>>>>> -Added iommu_ops to struct dev_iommu based on the discussion with
>>> Robin.
>>>>> -Rebased against iommu-tree core branch.
>>>>
>>>> A gentle ping on this...
>>>
>>> Is there a convincing justification for maintaining yet another copy of
>>> the ops pointer rather than simply dereferencing iommu_dev->ops at point
>>> of use?
>>>
>>
>> TBH, nothing I can think of now. That was mainly the way I interpreted your
>> suggestion
>> from the v1. Now it looks like you didn’t mean it :). I am Ok to rework it to
>> dereference
>> it from iommu_dev. Please let me know.
>
> So we can do something like this,
>
> index fd76e2f579fe..5fd31a3cec18 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2865,10 +2865,12 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
> */
> int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
> {
> - const struct iommu_ops *ops = dev->bus->iommu_ops;
> + if (dev->iommu && dev->iommu->iommu_dev && dev->iommu->iommu_dev->ops)
> + struct iommu_ops *ops = dev->iommu->iommu_dev->ops;
>
> - if (ops && ops->dev_enable_feat)
> - return ops->dev_enable_feat(dev, feat);
> + if (ops->dev_enable_feat)
> + return ops->dev_enable_feat(dev, feat);
> + }
>
> return -ENODEV;
> }
>
> Again, not sure we need to do the checking for iommu->dev and ops here. If the
> dev->iommu is set, is it safe to assume that we have a valid iommu->iommu_dev
> and ops always? (May be it is safer to do the checking in case something
> else breaks this assumption in future). Please let me know your thoughts.
I think it *could* happen that dev->iommu is set by iommu_fwspec_init()
but iommu_probe_device() later refuses the device for whatever reason,
so we would still need to check iommu->iommu_dev to be completely safe.
We can assume iommu_dev->ops is valid, since if the IOMMU driver has
returned something bogus from .probe_device then it's a major bug in
that driver and crashing is the best indicator :)
Robin.
>
> Thanks,
> Shameer
>
>
> _______________________________________________
> iommu mailing list
> iommu@lists.linux-foundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/iommu
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
@ 2021-02-01 12:40 Shameer Kolothum
0 siblings, 0 replies; 6+ messages in thread
From: Shameer Kolothum @ 2021-02-01 12:40 UTC (permalink / raw)
To: linux-kernel, iommu
Cc: joro, robin.murphy, jean-philippe, will, prime.zeng, linuxarm
The device iommu probe/attach might have failed leaving dev->iommu
to NULL and device drivers may still invoke these functions resulting
in a crash in iommu vendor driver code. Hence make sure we check that.
Also added iommu_ops to the "struct dev_iommu" and set it if the dev
is successfully associated with an iommu.
Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device")
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
---
v1 --> v2:
-Added iommu_ops to struct dev_iommu based on the discussion with Robin.
-Rebased against iommu-tree core branch.
---
drivers/iommu/iommu.c | 19 +++++++------------
include/linux/iommu.h | 2 ++
2 files changed, 9 insertions(+), 12 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index fd76e2f579fe..6023d0b7c542 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -217,6 +217,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
}
dev->iommu->iommu_dev = iommu_dev;
+ dev->iommu->ops = iommu_dev->ops;
group = iommu_group_get_for_dev(dev);
if (IS_ERR(group)) {
@@ -2865,10 +2866,8 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
*/
int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat)
{
- const struct iommu_ops *ops = dev->bus->iommu_ops;
-
- if (ops && ops->dev_enable_feat)
- return ops->dev_enable_feat(dev, feat);
+ if (dev->iommu && dev->iommu->ops->dev_enable_feat)
+ return dev->iommu->ops->dev_enable_feat(dev, feat);
return -ENODEV;
}
@@ -2881,10 +2880,8 @@ EXPORT_SYMBOL_GPL(iommu_dev_enable_feature);
*/
int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
{
- const struct iommu_ops *ops = dev->bus->iommu_ops;
-
- if (ops && ops->dev_disable_feat)
- return ops->dev_disable_feat(dev, feat);
+ if (dev->iommu && dev->iommu->ops->dev_disable_feat)
+ return dev->iommu->ops->dev_disable_feat(dev, feat);
return -EBUSY;
}
@@ -2892,10 +2889,8 @@ EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat)
{
- const struct iommu_ops *ops = dev->bus->iommu_ops;
-
- if (ops && ops->dev_feat_enabled)
- return ops->dev_feat_enabled(dev, feat);
+ if (dev->iommu && dev->iommu->ops->dev_feat_enabled)
+ return dev->iommu->ops->dev_feat_enabled(dev, feat);
return false;
}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 524ffc2ff64f..ff0c76bdfb67 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -354,6 +354,7 @@ struct iommu_fault_param {
* @fault_param: IOMMU detected device fault reporting data
* @fwspec: IOMMU fwspec data
* @iommu_dev: IOMMU device this device is linked to
+ * @ops: iommu-ops for talking to the iommu_dev
* @priv: IOMMU Driver private data
*
* TODO: migrate other per device data pointers under iommu_dev_data, e.g.
@@ -364,6 +365,7 @@ struct dev_iommu {
struct iommu_fault_param *fault_param;
struct iommu_fwspec *fwspec;
struct iommu_device *iommu_dev;
+ const struct iommu_ops *ops;
void *priv;
};
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-02-16 13:46 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-02-12 14:54 [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions Shameerali Kolothum Thodi
2021-02-12 16:38 ` Robin Murphy
2021-02-12 16:44 ` Shameerali Kolothum Thodi
2021-02-12 17:28 ` Shameerali Kolothum Thodi
2021-02-16 13:45 ` Robin Murphy
-- strict thread matches above, loose matches on Subject: below --
2021-02-01 12:40 Shameer Kolothum
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).