| Message ID | 23-v2-8d1dc464eac9+10f-iommu_all_defdom_jgg@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | iommu: Make default_domain's mandatory | expand |
On 2023-05-16 01:00, 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 mentioned before, we already know we're going to need additional flags (and possibly data) to cover the existing set_pgtable_quirks use-case plus new stuff like the proposed dirty-tracking enable, so I'd be inclined to either add an extensible structure argument now to avoid future churn, or just not bother adding the device argument either until drivers can actually use it. > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> > --- > drivers/iommu/iommu.c | 18 +++++++++++++++--- > include/linux/iommu.h | 3 +++ > 2 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index c4cac1dcf80610..15aa51c356bd74 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -1995,14 +1995,25 @@ void iommu_set_fault_handler(struct iommu_domain *domain, > EXPORT_SYMBOL_GPL(iommu_set_fault_handler); > > static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops, > + struct device *dev, > unsigned int type) > { > struct iommu_domain *domain; > > if (type == IOMMU_DOMAIN_IDENTITY && ops->identity_domain) > return ops->identity_domain; > + else if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && > + ops->domain_alloc_paging) { > + /* > + * For now exclude DMA_FQ since it is still a driver policy > + * decision through domain_alloc() if we can use FQ mode. > + */ That's sorted now, so the type test can neatly collapse down to "type & __IOMMU_DOMAIN_PAGING". Thanks, Robin. > + domain = ops->domain_alloc_paging(dev); > + } else if (ops->domain_alloc) > + domain = ops->domain_alloc(type); > + else > + return NULL; > > - domain = ops->domain_alloc(type); > if (!domain) > return NULL; > > @@ -2033,14 +2044,15 @@ __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type) > > lockdep_assert_held(&group->mutex); > > - return __iommu_domain_alloc(dev_iommu_ops(dev), type); > + return __iommu_domain_alloc(dev_iommu_ops(dev), dev, type); > } > > struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus) > { > if (bus == NULL || bus->iommu_ops == NULL) > return NULL; > - return __iommu_domain_alloc(bus->iommu_ops, IOMMU_DOMAIN_UNMANAGED); > + return __iommu_domain_alloc(bus->iommu_ops, NULL, > + IOMMU_DOMAIN_UNMANAGED); > } > EXPORT_SYMBOL_GPL(iommu_domain_alloc); > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 387746f8273c99..18b0df42cc80d1 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -227,6 +227,8 @@ 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 that can be used for > + * UNMANAGED, DMA, and DMA_FQ domain types. > * @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 +260,7 @@ 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 Thu, Jun 01, 2023 at 08:17:56PM +0100, Robin Murphy wrote: > On 2023-05-16 01:00, 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 mentioned before, we already know we're going to need additional flags > (and possibly data) to cover the existing set_pgtable_quirks use-case plus > new stuff like the proposed dirty-tracking enable, so I'd be inclined to > either add an extensible structure argument now to avoid future > churn, I think I said this doesn't really work out because you still have to go into every driver and code up a 'does not support' check and fail if any new extension is added. Basically the same churn as adding a function argument. Adding more ops is a possible smoother way to support this. Keep alloc_paging() for these simple drivers and we can add an op with a big signature and structure or whatever for the fewer fully featured drivers. This way the core code can do the 'do not support' checks in one place based on the set ops and we keep boiler plate code out of alot of drivers. > or just not bother adding the device argument either until drivers > can actually use it. I debated this, I figured we'd use it pretty quickly, but certainly it can be taken out. > > @@ -1995,14 +1995,25 @@ void iommu_set_fault_handler(struct iommu_domain *domain, > > EXPORT_SYMBOL_GPL(iommu_set_fault_handler); > > static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops, > > + struct device *dev, > > unsigned int type) > > { > > struct iommu_domain *domain; > > if (type == IOMMU_DOMAIN_IDENTITY && ops->identity_domain) > > return ops->identity_domain; > > + else if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && > > + ops->domain_alloc_paging) { > > + /* > > + * For now exclude DMA_FQ since it is still a driver policy > > + * decision through domain_alloc() if we can use FQ mode. > > + */ > > That's sorted now, so the type test can neatly collapse down to "type & > __IOMMU_DOMAIN_PAGING". Thanks, I rebase it on Joerg's tree with that series and fix it up Jason
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index c4cac1dcf80610..15aa51c356bd74 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1995,14 +1995,25 @@ void iommu_set_fault_handler(struct iommu_domain *domain, EXPORT_SYMBOL_GPL(iommu_set_fault_handler); static struct iommu_domain *__iommu_domain_alloc(const struct iommu_ops *ops, + struct device *dev, unsigned int type) { struct iommu_domain *domain; if (type == IOMMU_DOMAIN_IDENTITY && ops->identity_domain) return ops->identity_domain; + else if ((type == IOMMU_DOMAIN_UNMANAGED || type == IOMMU_DOMAIN_DMA) && + ops->domain_alloc_paging) { + /* + * For now exclude DMA_FQ since it is still a driver policy + * decision through domain_alloc() if we can use FQ mode. + */ + domain = ops->domain_alloc_paging(dev); + } else if (ops->domain_alloc) + domain = ops->domain_alloc(type); + else + return NULL; - domain = ops->domain_alloc(type); if (!domain) return NULL; @@ -2033,14 +2044,15 @@ __iommu_group_domain_alloc(struct iommu_group *group, unsigned int type) lockdep_assert_held(&group->mutex); - return __iommu_domain_alloc(dev_iommu_ops(dev), type); + return __iommu_domain_alloc(dev_iommu_ops(dev), dev, type); } struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus) { if (bus == NULL || bus->iommu_ops == NULL) return NULL; - return __iommu_domain_alloc(bus->iommu_ops, IOMMU_DOMAIN_UNMANAGED); + return __iommu_domain_alloc(bus->iommu_ops, NULL, + IOMMU_DOMAIN_UNMANAGED); } EXPORT_SYMBOL_GPL(iommu_domain_alloc); diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 387746f8273c99..18b0df42cc80d1 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -227,6 +227,8 @@ 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 that can be used for + * UNMANAGED, DMA, and DMA_FQ domain types. * @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 +260,7 @@ 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 | 18 +++++++++++++++--- include/linux/iommu.h | 3 +++ 2 files changed, 18 insertions(+), 3 deletions(-)