Messages in this thread | | | Subject | Re: [PATCH v6 1/9] iommu: Add APIs for multiple domains per device | From | Lu Baolu <> | Date | Thu, 14 Feb 2019 09:34:45 +0800 |
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Hi Jean,
On 2/13/19 7:55 PM, Jean-Philippe Brucker wrote: > Hi, > > I have a few boring nits and one question below
Thanks a lot for reviewing my patch.
> > 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."
Yours looks better. Thanks!
> >> 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()).
After reconsideration, I think my comments about this API isn't correct. It should be like,
* iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_AUX) - Detect both IOMMU and PCI endpoint devices supporting the feature (aux-domain here) without host driver dependency.
* iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) - Check the enabling status of the feature (aux-domain here). The aux-domain interfaces are available only if this returns true.
> >> >> * 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"
Sure.
> >> >> * 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.tian@intel.com> >> Liu Yi L <yi.l.liu@intel.com> >> Ashok Raj <ashok.raj@intel.com> >> Sanjay Kumar <sanjay.k.kumar@intel.com> >> Jacob Pan <jacob.jun.pan@linux.intel.com> >> Alex Williamson <alex.williamson@redhat.com> >> Jean-Philippe Brucker <jean-philippe.brucker@arm.com> >> Joerg Roedel <joro@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.raj@intel.com> >> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com> >> Cc: Kevin Tian <kevin.tian@intel.com> >> Cc: Liu Yi L <yi.l.liu@intel.com> >> Suggested-by: Kevin Tian <kevin.tian@intel.com> >> Suggested-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> >> Suggested-by: Joerg Roedel <jroedel@suse.de> >> Signed-off-by: Lu Baolu <baolu.lu@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"?
Yes. I will change this and above.
> >> + * 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"
Sure.
> >> 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.
Yes, -EBUSY sounds better.
iommu_dev_disable_feat() will not detach all aux-domains, it requires the device drivers to do so before calling it. So if it sees anything not cleaned up, it should return -EBUSY. And we should put it as a comment for this API so that the device drivers know it.
> > Thanks, > Jean
Best regards, Lu Baolu
> >> + */ >> +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 >> > >
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