Re: [PATCH v11 01/13] iommu: Introduce attach/detach_pasid_table API
From: Auger Eric
Date: Wed Apr 15 2020 - 10:52:42 EST
Hi Jacob,
On 4/15/20 12:15 AM, Jacob Pan wrote:
> Hi Eric,
>
> There are some discussions about how to size the uAPI data.
> https://lkml.org/lkml/2020/4/14/939
>
> I think the problem with the current scheme is that when uAPI data gets
> extended, if VFIO continue to use:
>
> minsz = offsetofend(struct vfio_iommu_type1_set_pasid_table, config);
> if (copy_from_user(&spt, (void __user *)arg, minsz))
>
> It may copy more data from user than what was setup by the user.
>
> So, as suggested by Alex, we could add argsz to the IOMMU uAPI struct.
> So if argsz > minsz, then fail the attach_table since kernel might be
> old, doesn't know about the extra data.
> If argsz <= minsz, kernel can support the attach_table but must process
> the data based on flags or config.
So I guess we would need both an argsz _u32 + a new flag _u32 right?
I am ok with that idea. Besides how will you manage for existing IOMMU
UAPIs? At some point you envisionned to have a getter at iommu api level
to retrieve the size of a structure for a given version, right?
Thanks
Eric
>
> Does it make sense to you?
>
>
> On Tue, 14 Apr 2020 17:05:55 +0200
> Eric Auger <eric.auger@xxxxxxxxxx> wrote:
>
>> From: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
>>
>> 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@xxxxxxx>
>> Signed-off-by: Liu, Yi L <yi.l.liu@xxxxxxxxxxxxxxx>
>> Signed-off-by: Ashok Raj <ashok.raj@xxxxxxxxx>
>> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
>> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>> Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
>> ---
>> drivers/iommu/iommu.c | 19 ++++++++++++++
>> include/linux/iommu.h | 18 ++++++++++++++
>> include/uapi/linux/iommu.h | 51
>> ++++++++++++++++++++++++++++++++++++++ 3 files changed, 88
>> insertions(+)
>>
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 2b471419e26c..b71ad56f8c99 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -1723,6 +1723,25 @@ int iommu_sva_unbind_gpasid(struct
>> iommu_domain *domain, struct device *dev, }
>> EXPORT_SYMBOL_GPL(iommu_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);
>> +}
>> +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 7ef8b0bda695..3e1057c3585a 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -248,6 +248,8 @@ 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
>> * @pgsize_bitmap: bitmap of all possible supported page sizes
>> * @owner: Driver module providing these ops
>> */
>> @@ -307,6 +309,9 @@ struct iommu_ops {
>> void *drvdata);
>> void (*sva_unbind)(struct iommu_sva *handle);
>> int (*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,
>> @@ -446,6 +451,9 @@ extern int iommu_sva_bind_gpasid(struct
>> iommu_domain *domain, struct device *dev, struct
>> iommu_gpasid_bind_data *data); 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 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, @@ -1048,6 +1056,16 @@ 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 4ad3496e5c43..8d00be10dc6d 100644
>> --- a/include/uapi/linux/iommu.h
>> +++ b/include/uapi/linux/iommu.h
>> @@ -321,4 +321,55 @@ struct iommu_gpasid_bind_data {
>> };
>> };
>>
>> +/**
>> + * 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
>> + * @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)
>> + * @smmuv3: table information when @format is
>> %IOMMU_PASID_FORMAT_SMMUV3
>> + */
>> +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 */
>
> [Jacob Pan]
>