Messages in this thread Patch in this message | | | Date | Tue, 28 Mar 2023 13:11:12 +0800 | Subject | Re: [PATCH v2 3/8] iommu/sva: Support reservation of global SVA PASIDs | From | Baolu Lu <> |
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On 3/28/23 7:21 AM, Jacob Pan wrote: > Devices that use Intel ENQCMD to submit work must use global PASIDs in > that the PASID are stored in a per CPU MSR. When such device need to > submit work for in-kernel DMA with PASID, it must allocate PASIDs from > the same global number space to avoid conflict. > > This patch introduces IOMMU SVA APIs to reserve and release global PASIDs. > It is expected that device drivers will use the allocated PASIDs to attach > to appropriate IOMMU domains for use. > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > --- > drivers/iommu/iommu-sva.c | 33 +++++++++++++++++++++++++++++++++ > include/linux/iommu.h | 14 ++++++++++++++ > 2 files changed, 47 insertions(+) > > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c > index c434b95dc8eb..84b9de84b3e0 100644 > --- a/drivers/iommu/iommu-sva.c > +++ b/drivers/iommu/iommu-sva.c > @@ -148,6 +148,39 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle) > } > EXPORT_SYMBOL_GPL(iommu_sva_get_pasid); > > +/** > + * @brief > + * Reserve a PASID from the SVA global number space. > + * > + * @param min starting range, inclusive > + * @param max ending range, inclusive > + * @return The reserved PASID on success or IOMMU_PASID_INVALID on failure. > + */ > +ioasid_t iommu_sva_reserve_pasid(ioasid_t min, ioasid_t max) > +{ > + int ret; > + > + if (!pasid_valid(min) || !pasid_valid(max) || > + min == 0 || max < min)
I still think we should make "min == 0" a valid case. The ARM/AMD/Intel drivers should reserve PASID 0 for special usage with this interface.
Probably we should also make "min == max" a valid case. Both @min and @max are inclusive.
> + return IOMMU_PASID_INVALID; > + > + ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL); > + if (ret < 0) > + return IOMMU_PASID_INVALID; > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(iommu_sva_reserve_pasid); > + > +void iommu_sva_release_pasid(ioasid_t pasid) > +{ > + if (!pasid_valid(pasid))
The caller should never release an invalid pasid. So perhaps,
if (WARN_ON(!pasid_valid(pasid))) return;
to discover bugs during development.
> + return; > + > + ida_free(&iommu_global_pasid_ida, pasid); > +} > +EXPORT_SYMBOL_GPL(iommu_sva_release_pasid); > + > /* > * I/O page fault handler for SVA > */ > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 54f535ff9868..0471089dc1d0 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -1187,6 +1187,9 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, > struct mm_struct *mm); > void iommu_sva_unbind_device(struct iommu_sva *handle); > u32 iommu_sva_get_pasid(struct iommu_sva *handle); > +ioasid_t iommu_sva_reserve_pasid(ioasid_t min, ioasid_t max); > +void iommu_sva_release_pasid(ioasid_t pasid); > + > #else > static inline struct iommu_sva * > iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) > @@ -1202,6 +1205,17 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle) > { > return IOMMU_PASID_INVALID; > } > + > +static inline ioasid_t iommu_sva_reserve_pasid(ioasid_t min, ioasid_t max) > +{ > + return IOMMU_PASID_INVALID; > +} > + > +static inline void iommu_sva_release_pasid(ioasid_t pasid) > +{ > + > +} > + > static inline void mm_pasid_init(struct mm_struct *mm) {} > static inline void mm_pasid_drop(struct mm_struct *mm) {} > #endif /* CONFIG_IOMMU_SVA */
Best regards, baolu
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