Hi, I have a few boring nits and one question below
On 13/02/2019 04:02, Lu Baolu wrote: > Sharing a physical PCI device in a finer-granularity way > is becoming a consensus in the industry. IOMMU vendors > are also engaging efforts to support such sharing as well > as possible. Among the efforts, the capability of support > finer-granularity DMA isolation is a common requirement > due to the security consideration. With finer-granularity > DMA isolation, all DMA requests out of or to a subset of > a physical PCI device can be protected by the IOMMU. That last sentence seems strange, how about "With finer-granularity DMA isolation, subsets of a PCI function can be isolated from each others by the IOMMU." > As a > result, there is a request in software to attach multiple > domains to a physical PCI device. One example of such use > model is the Intel Scalable IOV [1] [2]. The Intel vt-d > 3.0 spec [3] introduces the scalable mode which enables > PASID granularity DMA isolation. > > This adds the APIs to support multiple domains per device. > In order to ease the discussions, we call it 'a domain in > auxiliary mode' or simply 'auxiliary domain' when multiple > domains are attached to a physical device. > > The APIs include: > > * iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX) > - Check whether both IOMMU and device support IOMMU aux > domain feature. Below aux-domain specific interfaces > are available only after this returns true. s/after/if/ since calling has_feature() shouldn't be a prerequisite to using the aux-domain interface (unlike calling enable_feature()). > > * iommu_dev_enable/disable_feature(dev, IOMMU_DEV_FEAT_AUX) > - Enable/disable device specific aux-domain feature. > > * iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) > - Check whether the aux domain specific feature enabled or > not. "is enabled" > > * iommu_aux_attach_device(domain, dev) > - Attaches @domain to @dev in the auxiliary mode. Multiple > domains could be attached to a single device in the > auxiliary mode with each domain representing an isolated > address space for an assignable subset of the device. > > * iommu_aux_detach_device(domain, dev) > - Detach @domain which has been attached to @dev in the > auxiliary mode. > > * iommu_aux_get_pasid(domain, dev) > - Return ID used for finer-granularity DMA translation. > For the Intel Scalable IOV usage model, this will be > a PASID. The device which supports Scalable IOV needs > to write this ID to the device register so that DMA > requests could be tagged with a right PASID prefix. > > This has been updated with the latest proposal from Joerg > posted here [5]. > > Many people involved in discussions of this design. > > Kevin Tian <kevin.t...@intel.com> > Liu Yi L <yi.l....@intel.com> > Ashok Raj <ashok....@intel.com> > Sanjay Kumar <sanjay.k.ku...@intel.com> > Jacob Pan <jacob.jun....@linux.intel.com> > Alex Williamson <alex.william...@redhat.com> > Jean-Philippe Brucker <jean-philippe.bruc...@arm.com> > Joerg Roedel <j...@8bytes.org> > > and some discussions can be found here [4] [5]. > > [1] > https://software.intel.com/en-us/download/intel-scalable-io-virtualization-technical-specification > [2] https://schd.ws/hosted_files/lc32018/00/LC3-SIOV-final.pdf > [3] > https://software.intel.com/en-us/download/intel-virtualization-technology-for-directed-io-architecture-specification > [4] https://lkml.org/lkml/2018/7/26/4 > [5] https://www.spinics.net/lists/iommu/msg31874.html > > Cc: Ashok Raj <ashok....@intel.com> > Cc: Jacob Pan <jacob.jun....@linux.intel.com> > Cc: Kevin Tian <kevin.t...@intel.com> > Cc: Liu Yi L <yi.l....@intel.com> > Suggested-by: Kevin Tian <kevin.t...@intel.com> > Suggested-by: Jean-Philippe Brucker <jean-philippe.bruc...@arm.com> > Suggested-by: Joerg Roedel <jroe...@suse.de> > Signed-off-by: Lu Baolu <baolu...@linux.intel.com> > --- > drivers/iommu/iommu.c | 91 +++++++++++++++++++++++++++++++++++++++++++ > include/linux/iommu.h | 70 +++++++++++++++++++++++++++++++++ > 2 files changed, 161 insertions(+) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 3ed4db334341..d0b323e8357f 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -2033,3 +2033,94 @@ int iommu_fwspec_add_ids(struct device *dev, u32 > *ids, int num_ids) > return 0; > } > EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids); > + > +/* > + * Per device IOMMU features. > + */ > +bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features > feat) > +{ > + const struct iommu_ops *ops = dev->bus->iommu_ops; > + > + if (ops && ops->dev_has_feat) > + return ops->dev_has_feat(dev, feat); > + > + return false; > +} > +EXPORT_SYMBOL_GPL(iommu_dev_has_feature); > + > +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); > + > + return -ENODEV; > +} > +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); > + > + return -ENODEV; > +} > +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); > + > + return false; > +} > +EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled); > + > +/* > + * Aux-domain specific attach/detach. > + * > + * Only works if iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX) returns > true. Rather "Only works if iommu_dev_feature_enabled(dev, AUX) returns true"? > + * Also, as long as domains are attached to a device through this > interface, > + * any tries to call iommu_attach_device() should fail > (iommu_detach_device() > + * can't fail, so we fail on the tryint to re-attach). This should make "when trying to re-attach" > us safe > + * against a device being attached to a guest as a whole while there > are still > + * pasid users on it (aux and sva). A related question: is calling iommu_dev_disable_feat(dev, AUX) enough to detach all auxiliary domains? I guess device drivers will always need to tidy contexts up one by one, so maybe iommu_dev_disable_feat(dev, AUX) can return -EBUSY in this case? I think we need to specify this in a comment so device drivers know how to clean up. Thanks, Jean > + */ > +int iommu_aux_attach_device(struct iommu_domain *domain, struct device > *dev) > +{ > + int ret = -ENODEV; > + > + if (domain->ops->aux_attach_dev) > + ret = domain->ops->aux_attach_dev(domain, dev); > + > + if (!ret) > + trace_attach_device_to_domain(dev); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_aux_attach_device); > + > +void iommu_aux_detach_device(struct iommu_domain *domain, struct device > *dev) > +{ > + if (domain->ops->aux_detach_dev) { > + domain->ops->aux_detach_dev(domain, dev); > + trace_detach_device_from_domain(dev); > + } > +} > +EXPORT_SYMBOL_GPL(iommu_aux_detach_device); > + > +int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev) > +{ > + int ret = -ENODEV; > + > + if (domain->ops->aux_get_pasid) > + ret = domain->ops->aux_get_pasid(domain, dev); > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_aux_get_pasid); > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index e90da6b6f3d1..831eb29b35c5 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -156,6 +156,11 @@ struct iommu_resv_region { > enum iommu_resv_type type; > }; > > +/* Per device IOMMU features */ > +enum iommu_dev_features { > + IOMMU_DEV_FEAT_AUX, /* Aux-domain feature */ > +}; > + > #ifdef CONFIG_IOMMU_API > > /** > @@ -183,6 +188,11 @@ struct iommu_resv_region { > * @domain_window_enable: Configure and enable a particular window for > a domain > * @domain_window_disable: Disable a particular window for a domain > * @of_xlate: add OF master IDs to iommu grouping > + * @dev_has/enable/disable_feat: per device entries to check/enable/disable > + * iommu specific features. > + * @dev_feat_enabled: check enabled feature > + * @aux_attach/detach_dev: aux-domain specific attach/detach entries. > + * @aux_get_pasid: get the pasid given an aux-domain > * @pgsize_bitmap: bitmap of all possible supported page sizes > */ > struct iommu_ops { > @@ -226,6 +236,17 @@ struct iommu_ops { > int (*of_xlate)(struct device *dev, struct of_phandle_args *args); > bool (*is_attach_deferred)(struct iommu_domain *domain, struct > device *dev); > > + /* Per device IOMMU features */ > + bool (*dev_has_feat)(struct device *dev, enum iommu_dev_features f); > + bool (*dev_feat_enabled)(struct device *dev, enum > iommu_dev_features f); > + int (*dev_enable_feat)(struct device *dev, enum > iommu_dev_features f); > + int (*dev_disable_feat)(struct device *dev, enum > iommu_dev_features f); > + > + /* Aux-domain specific attach/detach entries */ > + int (*aux_attach_dev)(struct iommu_domain *domain, struct device > *dev); > + void (*aux_detach_dev)(struct iommu_domain *domain, struct > device *dev); > + int (*aux_get_pasid)(struct iommu_domain *domain, struct device > *dev); > + > unsigned long pgsize_bitmap; > }; > > @@ -412,6 +433,14 @@ static inline void dev_iommu_fwspec_set(struct > device *dev, > int iommu_probe_device(struct device *dev); > void iommu_release_device(struct device *dev); > > +bool iommu_dev_has_feature(struct device *dev, enum iommu_dev_features f); > +int iommu_dev_enable_feature(struct device *dev, enum > iommu_dev_features f); > +int iommu_dev_disable_feature(struct device *dev, enum > iommu_dev_features f); > +bool iommu_dev_feature_enabled(struct device *dev, enum > iommu_dev_features f); > +int iommu_aux_attach_device(struct iommu_domain *domain, struct device > *dev); > +void iommu_aux_detach_device(struct iommu_domain *domain, struct device > *dev); > +int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev); > + > #else /* CONFIG_IOMMU_API */ > > struct iommu_ops {}; > @@ -696,6 +725,47 @@ const struct iommu_ops > *iommu_ops_from_fwnode(struct fwnode_handle *fwnode) > return NULL; > } > > +static inline bool > +iommu_dev_has_feature(struct device *dev, enum iommu_dev_features feat) > +{ > + return false; > +} > + > +static inline bool > +iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat) > +{ > + return false; > +} > + > +static inline int > +iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat) > +{ > + return -ENODEV; > +} > + > +static inline int > +iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat) > +{ > + return -ENODEV; > +} > + > +static inline int > +iommu_aux_attach_device(struct iommu_domain *domain, struct device *dev) > +{ > + return -ENODEV; > +} > + > +static inline void > +iommu_aux_detach_device(struct iommu_domain *domain, struct device *dev) > +{ > +} > + > +static inline int > +iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev) > +{ > + return -ENODEV; > +} > + > #endif /* CONFIG_IOMMU_API */ > > #ifdef CONFIG_IOMMU_DEBUGFS > -- > 2.17.1 >
