Messages in this thread | | | Date | Fri, 3 Mar 2023 10:24:42 +0800 | Subject | Re: [PATCH v4 3/6] iommu/sva: Stop using ioasid_set for SVA | From | Baolu Lu <> |
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On 3/3/23 1:17 AM, Jacob Pan wrote: > Hi Baolu, > > On Thu, 2 Mar 2023 21:01:42 +0800, Baolu Lu <baolu.lu@linux.intel.com> > wrote: > >> On 2023/3/2 7:56, Jacob Pan wrote: >>> From: Jason Gunthorpe <jgg@nvidia.com> >>> >>> Instead SVA drivers can use a simple global IDA to allocate PASIDs for >>> each mm_struct. >>> >>> Future work would be to allow drivers using the SVA APIs to reserve >>> global PASIDs from this IDA for their internal use, eg with the DMA API >>> PASID support. >>> >>> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> >>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> >>> --- >>> v4: >>> - Keep GFP_ATOMIC flag for PASID allocation, will changed to >>> GFP_KERNEL in a separate patch. >>> --- >>> drivers/iommu/iommu-sva.c | 62 ++++++++++----------------------------- >>> drivers/iommu/iommu-sva.h | 3 -- >>> 2 files changed, 15 insertions(+), 50 deletions(-) >>> >>> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c >>> index 376b2a9e2543..297852ae5e7c 100644 >>> --- a/drivers/iommu/iommu-sva.c >>> +++ b/drivers/iommu/iommu-sva.c >>> @@ -9,26 +9,13 @@ >>> #include "iommu-sva.h" >>> >>> static DEFINE_MUTEX(iommu_sva_lock); >>> -static DECLARE_IOASID_SET(iommu_sva_pasid); >>> +static DEFINE_IDA(iommu_global_pasid_ida); >>> >>> -/** >>> - * iommu_sva_alloc_pasid - Allocate a PASID for the mm >>> - * @mm: the mm >>> - * @min: minimum PASID value (inclusive) >>> - * @max: maximum PASID value (inclusive) >>> - * >>> - * Try to allocate a PASID for this mm, or take a reference to the >>> existing one >>> - * provided it fits within the [@min, @max] range. On success the >>> PASID is >>> - * available in mm->pasid and will be available for the lifetime of >>> the mm. >>> - * >>> - * Returns 0 on success and < 0 on error. >>> - */ >>> -int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t >>> max) +static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t >>> min, ioasid_t max) { >>> - int ret = 0; >>> - ioasid_t pasid; >>> + int ret; >>> >>> - if (min == INVALID_IOASID || max == INVALID_IOASID || >>> + if (min == IOMMU_PASID_INVALID || max == IOMMU_PASID_INVALID || >>> min == 0 || max < min) >> >> It's irrelevant to this patch. Just out of curiosity, why do we need to >> exclude PASID 0 here? I just had a quick look at PCI spec section 6.20. >> The spec does not state that PASID 0 is invalid. >> > my understanding is that ARM reserves PASID0, unlike VT-d where RID_PASID > is programmable.
I suppose the common thing is reserving some kind of special PASIDs.
> >>> return -EINVAL; >>> >>> @@ -37,39 +24,20 @@ int iommu_sva_alloc_pasid(struct mm_struct *mm, >>> ioasid_t min, ioasid_t max) if (pasid_valid(mm->pasid)) { >>> if (mm->pasid < min || mm->pasid >= max) >>> ret = -EOVERFLOW; >>> + else >>> + ret = 0; >> >> Nit: >> >> If you didn't change "int ret = 0" to "int ret", we don't need above two >> lines. Did I miss anything? >> > you are right > >>> goto out; >>> } >>> >>> - pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm); >>> - if (!pasid_valid(pasid)) >>> - ret = -ENOMEM; >>> - else >>> - mm->pasid = ret; >>> + ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, >>> GFP_ATOMIC); >>> + if (ret < min) >> >> Nit: >> ret < 0? > will do > >> ida_alloc_range() returns negative error number on failure. >> >>> + goto out; >>> + mm->pasid = ret; >>> + ret = 0; >>> out: >>> mutex_unlock(&iommu_sva_lock); >>> return ret; >>> } >>> -EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid); >>> - >>> -/* ioasid_find getter() requires a void * argument */ >>> -static bool __mmget_not_zero(void *mm) >>> -{ >>> - return mmget_not_zero(mm); >>> -} >>> - >>> -/** >>> - * iommu_sva_find() - Find mm associated to the given PASID >>> - * @pasid: Process Address Space ID assigned to the mm >>> - * >>> - * On success a reference to the mm is taken, and must be released >>> with mmput(). >>> - * >>> - * Returns the mm corresponding to this PASID, or an error if not >>> found. >>> - */ >>> -struct mm_struct *iommu_sva_find(ioasid_t pasid) >>> -{ >>> - return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero); >>> -} >>> -EXPORT_SYMBOL_GPL(iommu_sva_find); >> >> Removing iommu_sva_find() has nothing to do with the intention of this >> patch. Perhaps make it in a separated patch? > will do > >>> >>> /** >>> * iommu_sva_bind_device() - Bind a process address space to a device >>> @@ -241,8 +209,8 @@ iommu_sva_handle_iopf(struct iommu_fault *fault, >>> void *data) >>> void mm_pasid_drop(struct mm_struct *mm) >>> { >>> - if (pasid_valid(mm->pasid)) { >>> - ioasid_free(mm->pasid); >>> - mm->pasid = INVALID_IOASID; >>> - } >>> + if (likely(!pasid_valid(mm->pasid))) >> >> Why is this a likely? > most mm does not have a PASID, thus initialized with invalid ioasid during > fork. This function is called for every mm.
Make sense.
> >>> + return; >>> + >>> + ida_free(&iommu_global_pasid_ida, mm->pasid); >>> } >>> diff --git a/drivers/iommu/iommu-sva.h b/drivers/iommu/iommu-sva.h >>> index 7215a761b962..c22d0174ad61 100644 >>> --- a/drivers/iommu/iommu-sva.h >>> +++ b/drivers/iommu/iommu-sva.h >>> @@ -8,9 +8,6 @@ >>> #include <linux/ioasid.h> >>> #include <linux/mm_types.h> >>> >>> -int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t >>> max); -struct mm_struct *iommu_sva_find(ioasid_t pasid); >>> - >>> /* I/O Page fault */ >>> struct device; >>> struct iommu_fault; >> >> Best regards, >> baolu > > > Thanks, > > Jacob
Best regards, baolu
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