Hi Kevin, On 4/16/20 3:28 PM, Tian, Kevin wrote: >> From: Auger Eric <eric.au...@redhat.com> >> Sent: Thursday, April 16, 2020 8:43 PM >> >> Hi Kevin, >> On 4/16/20 2:09 PM, Tian, Kevin wrote: >>>> From: Liu, Yi L <yi.l....@intel.com> >>>> Sent: Thursday, April 16, 2020 6:40 PM >>>> >>>> Hi Alex, >>>> Still have a direction question with you. Better get agreement with you >>>> before heading forward. >>>> >>>>> From: Alex Williamson <alex.william...@redhat.com> >>>>> Sent: Friday, April 3, 2020 11:35 PM >>>> [...] >>>>>>>> + * >>>>>>>> + * returns: 0 on success, -errno on failure. >>>>>>>> + */ >>>>>>>> +struct vfio_iommu_type1_cache_invalidate { >>>>>>>> + __u32 argsz; >>>>>>>> + __u32 flags; >>>>>>>> + struct iommu_cache_invalidate_info cache_info; >>>>>>>> +}; >>>>>>>> +#define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE, >>>>> VFIO_BASE >>>>>>> + 24) >>>>>>> >>>>>>> The future extension capabilities of this ioctl worry me, I wonder if >>>>>>> we should do another data[] with flag defining that data as >>>> CACHE_INFO. >>>>>> >>>>>> Can you elaborate? Does it mean with this way we don't rely on iommu >>>>>> driver to provide version_to_size conversion and instead we just pass >>>>>> data[] to iommu driver for further audit? >>>>> >>>>> No, my concern is that this ioctl has a single function, strictly tied >>>>> to the iommu uapi. If we replace cache_info with data[] then we can >>>>> define a flag to specify that data[] is struct >>>>> iommu_cache_invalidate_info, and if we need to, a different flag to >>>>> identify data[] as something else. For example if we get stuck >>>>> expanding cache_info to meet new demands and develop a new uapi to >>>>> solve that, how would we expand this ioctl to support it rather than >>>>> also create a new ioctl? There's also a trade-off in making the ioctl >>>>> usage more difficult for the user. I'd still expect the vfio layer to >>>>> check the flag and interpret data[] as indicated by the flag rather >>>>> than just passing a blob of opaque data to the iommu layer though. >>>>> Thanks, >>>> >>>> Based on your comments about defining a single ioctl and a unified >>>> vfio structure (with a @data[] field) for pasid_alloc/free, bind/ >>>> unbind_gpasid, cache_inv. After some offline trying, I think it would >>>> be good for bind/unbind_gpasid and cache_inv as both of them use the >>>> iommu uapi definition. While the pasid alloc/free operation doesn't. >>>> It would be weird to put all of them together. So pasid alloc/free >>>> may have a separate ioctl. It would look as below. Does this direction >>>> look good per your opinion? >>>> >>>> ioctl #22: VFIO_IOMMU_PASID_REQUEST >>>> /** >>>> * @pasid: used to return the pasid alloc result when flags == >> ALLOC_PASID >>>> * specify a pasid to be freed when flags == FREE_PASID >>>> * @range: specify the allocation range when flags == ALLOC_PASID >>>> */ >>>> struct vfio_iommu_pasid_request { >>>> __u32 argsz; >>>> #define VFIO_IOMMU_ALLOC_PASID (1 << 0) >>>> #define VFIO_IOMMU_FREE_PASID (1 << 1) >>>> __u32 flags; >>>> __u32 pasid; >>>> struct { >>>> __u32 min; >>>> __u32 max; >>>> } range; >>>> }; >>>> >>>> ioctl #23: VFIO_IOMMU_NESTING_OP >>>> struct vfio_iommu_type1_nesting_op { >>>> __u32 argsz; >>>> __u32 flags; >>>> __u32 op; >>>> __u8 data[]; >>>> }; >>>> >>>> /* Nesting Ops */ >>>> #define VFIO_IOMMU_NESTING_OP_BIND_PGTBL 0 >>>> #define VFIO_IOMMU_NESTING_OP_UNBIND_PGTBL 1 >>>> #define VFIO_IOMMU_NESTING_OP_CACHE_INVLD 2 >>>> >>> >>> Then why cannot we just put PASID into the header since the >>> majority of nested usage is associated with a pasid? >>> >>> ioctl #23: VFIO_IOMMU_NESTING_OP >>> struct vfio_iommu_type1_nesting_op { >>> __u32 argsz; >>> __u32 flags; >>> __u32 op; >>> __u32 pasid; >>> __u8 data[]; >>> }; >>> >>> In case of SMMUv2 which supports nested w/o PASID, this field can >>> be ignored for that specific case. >> On my side I would prefer keeping the pasid in the data[]. This is not >> always used. >> >> For instance, in iommu_cache_invalidate_info/iommu_inv_pasid_info we >> devised flags to tell whether the PASID is used. >> > > But don't we include a PASID in both invalidate structures already? The pasid presence is indicated by the IOMMU_INV_ADDR_FLAGS_PASID flag.
For instance for nested stage SMMUv3 I current performs an ARCHID (asid) based invalidation only. Eric > > struct iommu_inv_addr_info { > #define IOMMU_INV_ADDR_FLAGS_PASID (1 << 0) > #define IOMMU_INV_ADDR_FLAGS_ARCHID (1 << 1) > #define IOMMU_INV_ADDR_FLAGS_LEAF (1 << 2) > __u32 flags; > __u32 archid; > __u64 pasid; > __u64 addr; > __u64 granule_size; > __u64 nb_granules; > }; > > struct iommu_inv_pasid_info { > #define IOMMU_INV_PASID_FLAGS_PASID (1 << 0) > #define IOMMU_INV_PASID_FLAGS_ARCHID (1 << 1) > __u32 flags; > __u32 archid; > __u64 pasid; > }; > > then consolidating the pasid field into generic header doesn't > hurt. the specific handler still rely on flags to tell whether it > is used? > > Thanks > Kevin > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu