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SubjectRe: [PATCH v5 1/8] iommu: Add APIs for multiple domains per device
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Hi,

On 1/14/19 7:22 PM, Jonathan Cameron wrote:
> On Thu, 10 Jan 2019 11:00:20 +0800
> Lu Baolu <baolu.lu@linux.intel.com> 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. 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.
>>
>> * iommu_dev_enable/disable_feature(dev, IOMMU_DEV_FEAT_AUX)
>> - Enable/disable device specific aux-domain feature.
>>
>> * 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>
>
> One trivial comment inline.

Thank you!

>
>> ---
>> drivers/iommu/iommu.c | 80 +++++++++++++++++++++++++++++++++++++++++++
>> include/linux/iommu.h | 61 +++++++++++++++++++++++++++++++++
>> 2 files changed, 141 insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 3ed4db334341..9166b6145409 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2033,3 +2033,83 @@ 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);
>> +
>> +/*
>> + * Aux-domain specific attach/detach.
>> + *
>> + * Only works if iommu_dev_has_feature(dev, IOMMU_DEV_FEAT_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 us safe
>
> when trying to re-attach. (perhaps?)

Yes. I will fix it.

Best regards,
Lu Baolu

>
>> + * against a device being attached to a guest as a whole while there are still
>> + * pasid users on it (aux and sva).
>> + */
>> +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..f4c3d2a2cc87 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 +188,10 @@ 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.
>> + * @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 +235,16 @@ 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);
>> + 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 +431,13 @@ 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 feat);
>> +int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat);
>> +int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat);
>> +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 +722,41 @@ 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 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
>
>
>

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