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    SubjectRe: [PATCH v4 04/22] iommu: Introduce attach/detach_pasid_table API
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    On 18/02/2019 13:54, Eric Auger wrote:
    > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
    >
    > In virtualization use case, when a guest is assigned
    > a PCI host device, protected by a virtual IOMMU on the guest,
    > the physical IOMMU must be programmed to be consistent with
    > the guest mappings. If the physical IOMMU supports two
    > translation stages it makes sense to program guest mappings
    > onto the first stage/level (ARM/Intel terminology) while the host
    > owns the stage/level 2.
    >
    > In that case, it is mandated to trap on guest configuration
    > settings and pass those to the physical iommu driver.
    >
    > This patch adds a new API to the iommu subsystem that allows
    > to set/unset the pasid table information.
    >
    > A generic iommu_pasid_table_config struct is introduced in
    > a new iommu.h uapi header. This is going to be used by the VFIO
    > user API.
    >
    > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
    > Signed-off-by: Liu, Yi L <yi.l.liu@linux.intel.com>
    > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
    > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
    > Signed-off-by: Eric Auger <eric.auger@redhat.com>
    >
    > ---
    >
    > This patch generalizes the API introduced by Jacob & co-authors in
    > https://lwn.net/Articles/754331/
    >
    > v3 -> v4:
    > - s/set_pasid_table/attach_pasid_table
    > - restore detach_pasid_table. Detach can be used on unwind path.
    > - add padding
    > - remove @abort
    > - signature used for config and format
    > - add comments for fields in the SMMU struct
    >
    > v2 -> v3:
    > - replace unbind/bind by set_pasid_table
    > - move table pointer and pasid bits in the generic part of the struct
    >
    > v1 -> v2:
    > - restore the original pasid table name
    > - remove the struct device * parameter in the API
    > - reworked iommu_pasid_smmuv3
    > ---
    > drivers/iommu/iommu.c | 19 +++++++++++++++
    > include/linux/iommu.h | 22 ++++++++++++++++++
    > include/uapi/linux/iommu.h | 47 ++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 88 insertions(+)
    >
    > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
    > index c297cdcf7f89..b3adb77cb14c 100644
    > --- a/drivers/iommu/iommu.c
    > +++ b/drivers/iommu/iommu.c
    > @@ -1545,6 +1545,25 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
    > }
    > EXPORT_SYMBOL_GPL(iommu_attach_device);
    >
    > +int iommu_attach_pasid_table(struct iommu_domain *domain,
    > + struct iommu_pasid_table_config *cfg)
    > +{
    > + if (unlikely(!domain->ops->attach_pasid_table))
    > + return -ENODEV;
    > +
    > + return domain->ops->attach_pasid_table(domain, cfg);
    > +}
    > +EXPORT_SYMBOL_GPL(iommu_attach_pasid_table);
    > +
    > +void iommu_detach_pasid_table(struct iommu_domain *domain)
    > +{
    > + if (unlikely(!domain->ops->detach_pasid_table))
    > + return;
    > +
    > + domain->ops->detach_pasid_table(domain);
    > +}
    > +EXPORT_SYMBOL_GPL(iommu_detach_pasid_table);
    > +
    > static void __iommu_detach_device(struct iommu_domain *domain,
    > struct device *dev)
    > {
    > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
    > index b38e0c100940..7045e26f3a7d 100644
    > --- a/include/linux/iommu.h
    > +++ b/include/linux/iommu.h
    > @@ -187,6 +187,8 @@ struct iommu_resv_region {
    > * @domain_window_disable: Disable a particular window for a domain
    > * @of_xlate: add OF master IDs to iommu grouping
    > * @pgsize_bitmap: bitmap of all possible supported page sizes
    > + * @attach_pasid_table: attach a pasid table
    > + * @detach_pasid_table: detach the pasid table

    Should go before pgsize_bitmap

    > */
    > struct iommu_ops {
    > bool (*capable)(enum iommu_cap);
    > @@ -229,6 +231,10 @@ 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);
    >
    > + int (*attach_pasid_table)(struct iommu_domain *domain,
    > + struct iommu_pasid_table_config *cfg);
    > + void (*detach_pasid_table)(struct iommu_domain *domain);
    > +
    > unsigned long pgsize_bitmap;
    > };
    >
    > @@ -339,6 +345,9 @@ extern int iommu_attach_device(struct iommu_domain *domain,
    > struct device *dev);
    > extern void iommu_detach_device(struct iommu_domain *domain,
    > struct device *dev);
    > +extern int iommu_attach_pasid_table(struct iommu_domain *domain,
    > + struct iommu_pasid_table_config *cfg);
    > +extern void iommu_detach_pasid_table(struct iommu_domain *domain);
    > extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
    > extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
    > extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
    > @@ -777,6 +786,19 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
    > return NULL;
    > }
    >
    > +static inline
    > +int iommu_attach_pasid_table(struct iommu_domain *domain,
    > + struct iommu_pasid_table_config *cfg)
    > +{
    > + return -ENODEV;
    > +}
    > +
    > +static inline
    > +void iommu_detach_pasid_table(struct iommu_domain *domain)
    > +{
    > + return -ENODEV;

    No return here. With that fixed:

    Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>

    > +}
    > +
    > #endif /* CONFIG_IOMMU_API */
    >
    > #ifdef CONFIG_IOMMU_DEBUGFS
    > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
    > index 7ebf23ed6ccb..e9065bfa5b24 100644
    > --- a/include/uapi/linux/iommu.h
    > +++ b/include/uapi/linux/iommu.h
    > @@ -112,4 +112,51 @@ struct iommu_fault {
    > struct iommu_fault_page_request prm;
    > };
    > };
    > +
    > +/**
    > + * SMMUv3 Stream Table Entry stage 1 related information
    > + * The PASID table is referred to as the context descriptor (CD) table.
    > + *
    > + * @s1fmt: STE s1fmt (format of the CD table: single CD, linear table
    > + or 2-level table)
    > + * @s1dss: STE s1dss (specifies the behavior when pasid_bits != 0
    > + and no pasid is passed along with the incoming transaction)
    > + * Please refer to the smmu 3.x spec (ARM IHI 0070A) for full details
    > + */
    > +struct iommu_pasid_smmuv3 {
    > +#define PASID_TABLE_SMMUV3_CFG_VERSION_1 1
    > + __u32 version;
    > + __u8 s1fmt;
    > + __u8 s1dss;
    > + __u8 padding[2];
    > +};
    > +
    > +/**
    > + * PASID table data used to bind guest PASID table to the host IOMMU
    > + * Note PASID table corresponds to the Context Table on ARM SMMUv3.
    > + *
    > + * @version: API version to prepare for future extensions
    > + * @format: format of the PASID table
    > + * @base_ptr: guest physical address of the PASID table
    > + * @pasid_bits: number of PASID bits used in the PASID table
    > + * @config: indicates whether the guest translation stage must
    > + * be translated, bypassed or aborted.
    > + */
    > +struct iommu_pasid_table_config {
    > +#define PASID_TABLE_CFG_VERSION_1 1
    > + __u32 version;
    > +#define IOMMU_PASID_FORMAT_SMMUV3 1
    > + __u32 format;
    > + __u64 base_ptr;
    > + __u8 pasid_bits;
    > +#define IOMMU_PASID_CONFIG_TRANSLATE 1
    > +#define IOMMU_PASID_CONFIG_BYPASS 2
    > +#define IOMMU_PASID_CONFIG_ABORT 3
    > + __u8 config;
    > + __u8 padding[6];
    > + union {
    > + struct iommu_pasid_smmuv3 smmuv3;
    > + };
    > +};
    > +
    > #endif /* _UAPI_IOMMU_H */
    >

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