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SubjectRe: [PATCH v13 01/15] iommu: Introduce attach/detach_pasid_table API
Hi Eric,

On Wed, 18 Nov 2020 12:21:37 +0100, Eric Auger <eric.auger@redhat.com>
wrote:

> 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>
>
> ---
>
> v12 -> v13:
> - Fix config check
>
> v11 -> v12:
> - add argsz, name the union
> ---
> drivers/iommu/iommu.c | 68 ++++++++++++++++++++++++++++++++++++++
> include/linux/iommu.h | 21 ++++++++++++
> include/uapi/linux/iommu.h | 54 ++++++++++++++++++++++++++++++
> 3 files changed, 143 insertions(+)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index b53446bb8c6b..978fe34378fb 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2171,6 +2171,74 @@ int iommu_uapi_sva_unbind_gpasid(struct
> iommu_domain *domain, struct device *dev }
> EXPORT_SYMBOL_GPL(iommu_uapi_sva_unbind_gpasid);
>
> +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);
> +}
> +
> +int iommu_uapi_attach_pasid_table(struct iommu_domain *domain,
> + void __user *uinfo)
> +{
> + struct iommu_pasid_table_config pasid_table_data = { 0 };
> + u32 minsz;
> +
> + if (unlikely(!domain->ops->attach_pasid_table))
> + return -ENODEV;
> +
> + /*
> + * No new spaces can be added before the variable sized union,
> the
> + * minimum size is the offset to the union.
> + */
> + minsz = offsetof(struct iommu_pasid_table_config, vendor_data);
> +
> + /* Copy minsz from user to get flags and argsz */
> + if (copy_from_user(&pasid_table_data, uinfo, minsz))
> + return -EFAULT;
> +
> + /* Fields before the variable size union are mandatory */
> + if (pasid_table_data.argsz < minsz)
> + return -EINVAL;
> +
> + /* PASID and address granu require additional info beyond minsz
> */
> + if (pasid_table_data.version != PASID_TABLE_CFG_VERSION_1)
> + return -EINVAL;
> + if (pasid_table_data.format == IOMMU_PASID_FORMAT_SMMUV3 &&
> + pasid_table_data.argsz <
> + offsetofend(struct iommu_pasid_table_config,
> vendor_data.smmuv3))
> + return -EINVAL;
> +
> + /*
> + * User might be using a newer UAPI header which has a larger
> data
> + * size, we shall support the existing flags within the current
> + * size. Copy the remaining user data _after_ minsz but not more
> + * than the current kernel supported size.
> + */
> + if (copy_from_user((void *)&pasid_table_data + minsz, uinfo +
> minsz,
> + min_t(u32, pasid_table_data.argsz,
> sizeof(pasid_table_data)) - minsz))
> + return -EFAULT;
> +
> + /* Now the argsz is validated, check the content */
> + if (pasid_table_data.config < IOMMU_PASID_CONFIG_TRANSLATE ||
> + pasid_table_data.config > IOMMU_PASID_CONFIG_ABORT)
> + return -EINVAL;
> +
> + return domain->ops->attach_pasid_table(domain,
> &pasid_table_data); +}
> +EXPORT_SYMBOL_GPL(iommu_uapi_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 b95a6f8db6ff..464fcbecf841 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -223,6 +223,8 @@ struct iommu_iotlb_gather {
> * @cache_invalidate: invalidate translation caches
> * @sva_bind_gpasid: bind guest pasid and mm
> * @sva_unbind_gpasid: unbind guest pasid and mm
> + * @attach_pasid_table: attach a pasid table
> + * @detach_pasid_table: detach the pasid table
> * @def_domain_type: device default domain type, return value:
> * - IOMMU_DOMAIN_IDENTITY: must use an identity domain
> * - IOMMU_DOMAIN_DMA: must use a dma domain
> @@ -287,6 +289,9 @@ struct iommu_ops {
> void *drvdata);
> void (*sva_unbind)(struct iommu_sva *handle);
> u32 (*sva_get_pasid)(struct iommu_sva *handle);
> + int (*attach_pasid_table)(struct iommu_domain *domain,
> + struct iommu_pasid_table_config *cfg);
> + void (*detach_pasid_table)(struct iommu_domain *domain);
>
> int (*page_response)(struct device *dev,
> struct iommu_fault_event *evt,
> @@ -434,6 +439,11 @@ extern int iommu_uapi_sva_unbind_gpasid(struct
> iommu_domain *domain, struct device *dev, void __user *udata);
> extern int iommu_sva_unbind_gpasid(struct iommu_domain *domain,
> struct device *dev, ioasid_t pasid);
> +extern int iommu_attach_pasid_table(struct iommu_domain *domain,
> + struct iommu_pasid_table_config
> *cfg); +extern int iommu_uapi_attach_pasid_table(struct iommu_domain
> *domain,
> + void __user *udata);
> +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,
> @@ -639,6 +649,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device
> *dev, void iommu_sva_unbind_device(struct iommu_sva *handle);
> u32 iommu_sva_get_pasid(struct iommu_sva *handle);
>
> +
> #else /* CONFIG_IOMMU_API */
>
> struct iommu_ops {};
> @@ -1020,6 +1031,16 @@ iommu_aux_get_pasid(struct iommu_domain *domain,
> struct device *dev) return -ENODEV;
> }
>
> +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) {}
> +
> static inline struct iommu_sva *
> iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata) {
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index e1d9e75f2c94..082d758dd016 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -338,4 +338,58 @@ struct iommu_gpasid_bind_data {
> } vendor;
> };
>
> +/**
> + * struct iommu_pasid_smmuv3 - ARM SMMUv3 Stream Table Entry stage 1
> related
> + * information
> + * @version: API version of this structure
> + * @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)
> + * @padding: reserved for future use (should be zero)
> + *
> + * The PASID table is referred to as the Context Descriptor (CD) table
> on ARM
> + * SMMUv3. Please refer to the ARM 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];
> +};
> +
> +/**
> + * struct iommu_pasid_table_config - PASID table data used to bind guest
> PASID
> + * table to the host IOMMU
> + * @argsz: User filled size of this data
> + * @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.
> + * @padding: reserved for future use (should be zero)
> + * @vendor_data.smmuv3: table information when @format is
> + * %IOMMU_PASID_FORMAT_SMMUV3
> + */
> +struct iommu_pasid_table_config {
> + __u32 argsz;
> +#define PASID_TABLE_CFG_VERSION_1 1
> + __u32 version;
> +#define IOMMU_PASID_FORMAT_SMMUV3 1
> + __u32 format;
There will be a u32 gap here, right? perhaps another padding?

> + __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[2];
> + union {
> + struct iommu_pasid_smmuv3 smmuv3;
> + } vendor_data;
> +};
> +
> #endif /* _UAPI_IOMMU_H */


Thanks,

Jacob

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