| Message ID | 18-v1-21cc72fcfb22+a7a-iommu_all_defdom_jgg@nvidia.com |
|---|---|
| State | New |
| Headers | show |
| Series | iommu: Make default_domain's mandatory | expand |
On 2023-05-01 19:03, Jason Gunthorpe wrote: > This callback requests the driver to create only a __IOMMU_DOMAIN_PAGING > domain, so it saves a few lines in a lot of drivers needlessly checking > the type. > > More critically, this allows us to sweep out all the > IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA checks from a lot of the > drivers, simplifying what is going on in the code and ultimately removing > the now-unused special cases in drivers where they did not support > IOMMU_DOMAIN_DMA. > > domain_alloc_paging() should return a struct iommu_domain that is > functionally compatible with ARM_DMA_USE_IOMMU, dma-iommu.c and iommufd. > > Be forwards looking and pass in a 'struct device *' argument. We can > provide this when allocating the default_domain. No drivers will look at > this. As discussed previously, we're going to want a way for callers to pass through various options as well, initially to replace iommu_set_pgtable_quirks() at the very least. Maybe passing an easily-extensible structure around is the even better option? (Wherein we could even strictly enforce "no drivers will look at this" for the moment by leaving it empty) I'm hoping I'll get another version of my bus ops removal out this cycle; there's obviously a lot of overlap here to figure out. > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> > --- > drivers/iommu/iommu.c | 40 ++++++++++++++++++++++++---------------- > include/linux/iommu.h | 2 ++ > 2 files changed, 26 insertions(+), 16 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index f20a031e2910b2..fee417df8f195d 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -93,6 +93,7 @@ static int iommu_bus_notifier(struct notifier_block *nb, > unsigned long action, void *data); > static void iommu_release_device(struct device *dev); > static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > + struct device *dev, > unsigned type); > static int __iommu_attach_device(struct iommu_domain *domain, > struct device *dev); > @@ -1618,12 +1619,12 @@ static int iommu_get_def_domain_type(struct device *dev) > } > > static struct iommu_domain * > -__iommu_group_alloc_default_domain(struct bus_type *bus, > +__iommu_group_alloc_default_domain(struct group_device *gdev, > struct iommu_group *group, int req_type) > { > if (group->default_domain && group->default_domain->type == req_type) > return group->default_domain; > - return __iommu_domain_alloc(bus, req_type); > + return __iommu_domain_alloc(gdev->dev->bus, gdev->dev, req_type); > } > > /* > @@ -1633,9 +1634,9 @@ __iommu_group_alloc_default_domain(struct bus_type *bus, > static struct iommu_domain * > iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) > { > - struct bus_type *bus = > - list_first_entry(&group->devices, struct group_device, list) > - ->dev->bus; > + struct group_device *gdev = > + list_first_entry(&group->devices, struct group_device, list); Eww, why pass around a group_device that nobody wants? Keeping the single dereference of ->dev here, rather than the three above and below, would be cleaner. And it makes my iommu_group_first_device() helper look even more appealing, if I dare say so myself :) > + const struct iommu_ops *ops = dev_iommu_ops(gdev->dev); > struct iommu_domain *dom; > > lockdep_assert_held(&group->mutex); > @@ -1645,14 +1646,15 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) > * domain. This should always be either an IDENTITY or PLATFORM domain. > * Do not use in new drivers. > */ > - if (bus->iommu_ops->default_domain) { > + if (ops->default_domain) { > if (req_type) > return ERR_PTR(-EINVAL); > - return bus->iommu_ops->default_domain; > + return ops->default_domain; > } > > if (req_type) > - return __iommu_group_alloc_default_domain(bus, group, req_type); > + return __iommu_group_alloc_default_domain(gdev, group, > + req_type); > > /* > * If ARM32 CONFIG_ARM_DMA_USE_IOMMU is enabled and the driver doesn't > @@ -1665,18 +1667,19 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) > IS_ENABLED(CONFIG_IOMMU_DMA))); > > return __iommu_group_alloc_default_domain( > - bus, group, IOMMU_DOMAIN_IDENTITY); > + gdev, group, IOMMU_DOMAIN_IDENTITY); > } > > /* The driver gave no guidance on what type to use, try the default */ > - dom = __iommu_group_alloc_default_domain(bus, group, iommu_def_domain_type); > + dom = __iommu_group_alloc_default_domain(gdev, group, > + iommu_def_domain_type); > if (dom) > return dom; > > /* Otherwise IDENTITY and DMA_FQ defaults will try DMA */ > if (iommu_def_domain_type == IOMMU_DOMAIN_DMA) > return NULL; > - dom = __iommu_group_alloc_default_domain(bus, group, IOMMU_DOMAIN_DMA); > + dom = __iommu_group_alloc_default_domain(gdev, group, IOMMU_DOMAIN_DMA); > if (!dom) > return NULL; > > @@ -1930,6 +1933,7 @@ void iommu_set_fault_handler(struct iommu_domain *domain, > EXPORT_SYMBOL_GPL(iommu_set_fault_handler); > > static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > + struct device *dev, > unsigned type) > { > struct iommu_domain *domain; > @@ -1940,7 +1944,11 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > if (type == IOMMU_DOMAIN_IDENTITY && bus->iommu_ops->identity_domain) > return bus->iommu_ops->identity_domain; > > - domain = bus->iommu_ops->domain_alloc(type); > + if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && Logically, "type & __IOMMU_DOMAIN_PAGING", otherwise we're already missing IOMMU_DOMAIN_DMA_FQ. Except maybe that's deliberate? Not sure how much I like the idea of a introducing new interface design that we clearly can't even convert all the current drivers to as it stands :/ > + bus->iommu_ops->domain_alloc_paging) > + domain = bus->iommu_ops->domain_alloc_paging(dev); > + else > + domain = bus->iommu_ops->domain_alloc(type); > if (!domain) > return NULL; > > @@ -1964,7 +1972,7 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > > struct iommu_domain *iommu_domain_alloc(struct bus_type *bus) > { > - return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED); > + return __iommu_domain_alloc(bus, NULL, IOMMU_DOMAIN_UNMANAGED); > } > EXPORT_SYMBOL_GPL(iommu_domain_alloc); > > @@ -3079,15 +3087,15 @@ static int __iommu_group_alloc_blocking_domain(struct iommu_group *group) > if (group->blocking_domain) > return 0; > > - group->blocking_domain = > - __iommu_domain_alloc(dev->dev->bus, IOMMU_DOMAIN_BLOCKED); > + group->blocking_domain = __iommu_domain_alloc(dev->dev->bus, dev->dev, > + IOMMU_DOMAIN_BLOCKED); > if (!group->blocking_domain) { > /* > * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED > * create an empty domain instead. > */ > group->blocking_domain = __iommu_domain_alloc( > - dev->dev->bus, IOMMU_DOMAIN_UNMANAGED); > + dev->dev->bus, dev->dev, IOMMU_DOMAIN_UNMANAGED); > if (!group->blocking_domain) > return -EINVAL; > } > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index f6a28ab78e607e..cc9aff2d213eec 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -227,6 +227,7 @@ struct iommu_iotlb_gather { > * struct iommu_ops - iommu ops and capabilities > * @capable: check capability > * @domain_alloc: allocate iommu domain > + * @domain_alloc_paging: Allocate an IOMMU_DOMAIN_UNMANAGED ...except for the other types of paging-capable domain which also exist and it also allocates :/ There remains good reason to keep track of the distinct subtypes of paging domain within the IOMMU core (i.e. between iommu.c and dma-iommu.c) even if drivers do finally get absolved of all the details. Sure we could come up with any number of different ways to encode those distinctions, but they wouldn't be objectively better than the domain flags and types we already have, they'd just be different. Thanks, Robin. > * @probe_device: Add device to iommu driver handling > * @release_device: Remove device from iommu driver handling > * @probe_finalize: Do final setup work after the device is added to an IOMMU > @@ -258,6 +259,7 @@ struct iommu_ops { > > /* Domain allocation and freeing by the iommu driver */ > struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type); > + struct iommu_domain *(*domain_alloc_paging)(struct device *dev); > > struct iommu_device *(*probe_device)(struct device *dev); > void (*release_device)(struct device *dev);
On Wed, May 03, 2023 at 06:17:58PM +0100, Robin Murphy wrote: > On 2023-05-01 19:03, Jason Gunthorpe wrote: > > This callback requests the driver to create only a __IOMMU_DOMAIN_PAGING > > domain, so it saves a few lines in a lot of drivers needlessly checking > > the type. > > > > More critically, this allows us to sweep out all the > > IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA checks from a lot of the > > drivers, simplifying what is going on in the code and ultimately removing > > the now-unused special cases in drivers where they did not support > > IOMMU_DOMAIN_DMA. > > > > domain_alloc_paging() should return a struct iommu_domain that is > > functionally compatible with ARM_DMA_USE_IOMMU, dma-iommu.c and iommufd. > > > > Be forwards looking and pass in a 'struct device *' argument. We can > > provide this when allocating the default_domain. No drivers will look at > > this. > > As discussed previously, we're going to want a way for callers to pass > through various options as well, initially to replace > iommu_set_pgtable_quirks() at the very least. Yeah, I like that direction > Maybe passing an easily-extensible structure around is the even > better option? (Wherein we could even strictly enforce "no drivers > will look at this" for the moment by leaving it empty) Can we leave this till when we get there? I think it makes sense to add an args struct and the first one can contain the quirk field. The trouble with this approach is we still have to get the alloc to reject inputs it doesn't understand. > I'm hoping I'll get another version of my bus ops removal out this cycle; > there's obviously a lot of overlap here to figure out. I think the places it needs to touch is slowly shrinking :) But it would be great to get the bus stuff going, we can organize the series in whatever order, but I think the "Consolidate the error handling around device attachment" series is good now so we should get it in Joerg's tree and start there. > > @@ -1633,9 +1634,9 @@ __iommu_group_alloc_default_domain(struct bus_type *bus, > > static struct iommu_domain * > > iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) > > { > > - struct bus_type *bus = > > - list_first_entry(&group->devices, struct group_device, list) > > - ->dev->bus; > > + struct group_device *gdev = > > + list_first_entry(&group->devices, struct group_device, list); > > Eww, why pass around a group_device that nobody wants? Oops, yeah, will fix > cleaner. And it makes my iommu_group_first_device() helper look even more > appealing, if I dare say so myself :) It is a good idea, but I seem to recall the count of users has reduced after my last two series > > @@ -1940,7 +1944,11 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > > if (type == IOMMU_DOMAIN_IDENTITY && bus->iommu_ops->identity_domain) > > return bus->iommu_ops->identity_domain; > > - domain = bus->iommu_ops->domain_alloc(type); > > + if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && > > Logically, "type & __IOMMU_DOMAIN_PAGING", otherwise we're already missing > IOMMU_DOMAIN_DMA_FQ. Except maybe that's deliberate? It is deliberate for now, if it included FQ it would cause a bunch of ARM64 drivers to switch to lazy mode. I'll add a comment. I have drafted a followup series that removes all the DMA/DMA_FQ/UNMANAGED checks from the remaining 6 drivers. I did this by adding an op flag 'prefer to use FQ' and made the core code drive the FQ decision from ops. But that is another series for another day.. > Not sure how much I like the idea of a introducing new interface > design that we clearly can't even convert all the current drivers to > as it stands :/ I wouldn't say that. This converts 14 of the drivers and leaves 6. The remaing 6 are more complicated and have to go in other series. eg I have to reorganize DMA_FQ first. Regardless, the point is not to be universal but to have a straight forward sign off that these 14 drivers have been audited and they don't have any policy logic in alloc_domain any more. Incremental progress.. > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > > index f6a28ab78e607e..cc9aff2d213eec 100644 > > --- a/include/linux/iommu.h > > +++ b/include/linux/iommu.h > > @@ -227,6 +227,7 @@ struct iommu_iotlb_gather { > > * struct iommu_ops - iommu ops and capabilities > > * @capable: check capability > > * @domain_alloc: allocate iommu domain > > + * @domain_alloc_paging: Allocate an IOMMU_DOMAIN_UNMANAGED > > ...except for the other types of paging-capable domain which also exist and > it also allocates :/ Yeah.. I can write something else here > There remains good reason to keep track of the distinct subtypes of paging > domain within the IOMMU core (i.e. between iommu.c and dma-iommu.c) even if > drivers do finally get absolved of all the details. It is hard to keep the details out of the drivers if the argument to ops->alloc_domain() encodes the details we want to keep opaque :) So I have been taking the approach of just removing the IOMMU_DOMAIN_xx text and related checks from the drivers as it becomes possible. This series is the first wack and does every driver except those that have dynamic identity domains. DMA_FQ is the logical next step on this thread > Sure we could come up with any number of different ways to encode > those distinctions, but they wouldn't be objectively better than the > domain flags and types we already have, they'd just be different. My general feeling is that we can remove them completely. At least DMA and DMA_FQ I think can be removed totally with some reorganizing. PAGING can become maybe (bool)domain->ops->iova_to_phys with some small work on the remaining 6 drivers. So we might just get down to SVA, IDENTITY and everything else Jason
On Wed, 2023-05-03 at 16:35 -0300, Jason Gunthorpe wrote: > On Wed, May 03, 2023 at 06:17:58PM +0100, Robin Murphy wrote: > > On 2023-05-01 19:03, Jason Gunthorpe wrote: > > > ---8<--- > > > > @@ -1940,7 +1944,11 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > > > if (type == IOMMU_DOMAIN_IDENTITY && bus->iommu_ops->identity_domain) > > > return bus->iommu_ops->identity_domain; > > > - domain = bus->iommu_ops->domain_alloc(type); > > > + if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && > > > > Logically, "type & __IOMMU_DOMAIN_PAGING", otherwise we're already missing > > IOMMU_DOMAIN_DMA_FQ. Except maybe that's deliberate? > > It is deliberate for now, if it included FQ it would cause a bunch of > ARM64 drivers to switch to lazy mode. I'll add a comment. > > I have drafted a followup series that removes all the > DMA/DMA_FQ/UNMANAGED checks from the remaining 6 drivers. I did this > by adding an op flag 'prefer to use FQ' and made the core code drive > the FQ decision from ops. Ah that sounds like it could fit very well with s390's need for an even lazier flush mode to handle the virtualized IOMMU with slow IOTLB flush case aka _SQ / single flush queue mode. When you have anything ready give me a ping and I can rework my DMA conversion on top of this.
On Thu, May 04, 2023 at 02:35:35PM +0200, Niklas Schnelle wrote: > On Wed, 2023-05-03 at 16:35 -0300, Jason Gunthorpe wrote: > > On Wed, May 03, 2023 at 06:17:58PM +0100, Robin Murphy wrote: > > > On 2023-05-01 19:03, Jason Gunthorpe wrote: > > > > > ---8<--- > > > > > > @@ -1940,7 +1944,11 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, > > > > if (type == IOMMU_DOMAIN_IDENTITY && bus->iommu_ops->identity_domain) > > > > return bus->iommu_ops->identity_domain; > > > > - domain = bus->iommu_ops->domain_alloc(type); > > > > + if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && > > > > > > Logically, "type & __IOMMU_DOMAIN_PAGING", otherwise we're already missing > > > IOMMU_DOMAIN_DMA_FQ. Except maybe that's deliberate? > > > > It is deliberate for now, if it included FQ it would cause a bunch of > > ARM64 drivers to switch to lazy mode. I'll add a comment. > > > > I have drafted a followup series that removes all the > > DMA/DMA_FQ/UNMANAGED checks from the remaining 6 drivers. I did this > > by adding an op flag 'prefer to use FQ' and made the core code drive > > the FQ decision from ops. > > Ah that sounds like it could fit very well with s390's need for an even > lazier flush mode to handle the virtualized IOMMU with slow IOTLB flush > case aka _SQ / single flush queue mode. When you have anything ready > give me a ping and I can rework my DMA conversion on top of this. I'd like to get your S390 dma-api conversion merged ASAP! I have this general objective to get the modern architectures onto dma-iommu.c because I want to add new things to the dma-api :\ I had imagined a new op flag because it is is pretty simple, but a op->get_performance or something that reports some data that could help dma-iommu.c decide if lazy mode is worthwhile and if there is other tuning sounds interesting too.. Jason
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index f20a031e2910b2..fee417df8f195d 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -93,6 +93,7 @@ static int iommu_bus_notifier(struct notifier_block *nb, unsigned long action, void *data); static void iommu_release_device(struct device *dev); static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, + struct device *dev, unsigned type); static int __iommu_attach_device(struct iommu_domain *domain, struct device *dev); @@ -1618,12 +1619,12 @@ static int iommu_get_def_domain_type(struct device *dev) } static struct iommu_domain * -__iommu_group_alloc_default_domain(struct bus_type *bus, +__iommu_group_alloc_default_domain(struct group_device *gdev, struct iommu_group *group, int req_type) { if (group->default_domain && group->default_domain->type == req_type) return group->default_domain; - return __iommu_domain_alloc(bus, req_type); + return __iommu_domain_alloc(gdev->dev->bus, gdev->dev, req_type); } /* @@ -1633,9 +1634,9 @@ __iommu_group_alloc_default_domain(struct bus_type *bus, static struct iommu_domain * iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) { - struct bus_type *bus = - list_first_entry(&group->devices, struct group_device, list) - ->dev->bus; + struct group_device *gdev = + list_first_entry(&group->devices, struct group_device, list); + const struct iommu_ops *ops = dev_iommu_ops(gdev->dev); struct iommu_domain *dom; lockdep_assert_held(&group->mutex); @@ -1645,14 +1646,15 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) * domain. This should always be either an IDENTITY or PLATFORM domain. * Do not use in new drivers. */ - if (bus->iommu_ops->default_domain) { + if (ops->default_domain) { if (req_type) return ERR_PTR(-EINVAL); - return bus->iommu_ops->default_domain; + return ops->default_domain; } if (req_type) - return __iommu_group_alloc_default_domain(bus, group, req_type); + return __iommu_group_alloc_default_domain(gdev, group, + req_type); /* * If ARM32 CONFIG_ARM_DMA_USE_IOMMU is enabled and the driver doesn't @@ -1665,18 +1667,19 @@ iommu_group_alloc_default_domain(struct iommu_group *group, int req_type) IS_ENABLED(CONFIG_IOMMU_DMA))); return __iommu_group_alloc_default_domain( - bus, group, IOMMU_DOMAIN_IDENTITY); + gdev, group, IOMMU_DOMAIN_IDENTITY); } /* The driver gave no guidance on what type to use, try the default */ - dom = __iommu_group_alloc_default_domain(bus, group, iommu_def_domain_type); + dom = __iommu_group_alloc_default_domain(gdev, group, + iommu_def_domain_type); if (dom) return dom; /* Otherwise IDENTITY and DMA_FQ defaults will try DMA */ if (iommu_def_domain_type == IOMMU_DOMAIN_DMA) return NULL; - dom = __iommu_group_alloc_default_domain(bus, group, IOMMU_DOMAIN_DMA); + dom = __iommu_group_alloc_default_domain(gdev, group, IOMMU_DOMAIN_DMA); if (!dom) return NULL; @@ -1930,6 +1933,7 @@ void iommu_set_fault_handler(struct iommu_domain *domain, EXPORT_SYMBOL_GPL(iommu_set_fault_handler); static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, + struct device *dev, unsigned type) { struct iommu_domain *domain; @@ -1940,7 +1944,11 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, if (type == IOMMU_DOMAIN_IDENTITY && bus->iommu_ops->identity_domain) return bus->iommu_ops->identity_domain; - domain = bus->iommu_ops->domain_alloc(type); + if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && + bus->iommu_ops->domain_alloc_paging) + domain = bus->iommu_ops->domain_alloc_paging(dev); + else + domain = bus->iommu_ops->domain_alloc(type); if (!domain) return NULL; @@ -1964,7 +1972,7 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, struct iommu_domain *iommu_domain_alloc(struct bus_type *bus) { - return __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED); + return __iommu_domain_alloc(bus, NULL, IOMMU_DOMAIN_UNMANAGED); } EXPORT_SYMBOL_GPL(iommu_domain_alloc); @@ -3079,15 +3087,15 @@ static int __iommu_group_alloc_blocking_domain(struct iommu_group *group) if (group->blocking_domain) return 0; - group->blocking_domain = - __iommu_domain_alloc(dev->dev->bus, IOMMU_DOMAIN_BLOCKED); + group->blocking_domain = __iommu_domain_alloc(dev->dev->bus, dev->dev, + IOMMU_DOMAIN_BLOCKED); if (!group->blocking_domain) { /* * For drivers that do not yet understand IOMMU_DOMAIN_BLOCKED * create an empty domain instead. */ group->blocking_domain = __iommu_domain_alloc( - dev->dev->bus, IOMMU_DOMAIN_UNMANAGED); + dev->dev->bus, dev->dev, IOMMU_DOMAIN_UNMANAGED); if (!group->blocking_domain) return -EINVAL; } diff --git a/include/linux/iommu.h b/include/linux/iommu.h index f6a28ab78e607e..cc9aff2d213eec 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -227,6 +227,7 @@ struct iommu_iotlb_gather { * struct iommu_ops - iommu ops and capabilities * @capable: check capability * @domain_alloc: allocate iommu domain + * @domain_alloc_paging: Allocate an IOMMU_DOMAIN_UNMANAGED * @probe_device: Add device to iommu driver handling * @release_device: Remove device from iommu driver handling * @probe_finalize: Do final setup work after the device is added to an IOMMU @@ -258,6 +259,7 @@ struct iommu_ops { /* Domain allocation and freeing by the iommu driver */ struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type); + struct iommu_domain *(*domain_alloc_paging)(struct device *dev); struct iommu_device *(*probe_device)(struct device *dev); void (*release_device)(struct device *dev);
This callback requests the driver to create only a __IOMMU_DOMAIN_PAGING domain, so it saves a few lines in a lot of drivers needlessly checking the type. More critically, this allows us to sweep out all the IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA checks from a lot of the drivers, simplifying what is going on in the code and ultimately removing the now-unused special cases in drivers where they did not support IOMMU_DOMAIN_DMA. domain_alloc_paging() should return a struct iommu_domain that is functionally compatible with ARM_DMA_USE_IOMMU, dma-iommu.c and iommufd. Be forwards looking and pass in a 'struct device *' argument. We can provide this when allocating the default_domain. No drivers will look at this. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> --- drivers/iommu/iommu.c | 40 ++++++++++++++++++++++++---------------- include/linux/iommu.h | 2 ++ 2 files changed, 26 insertions(+), 16 deletions(-)