Messages in this thread | | | Date | Thu, 5 Oct 2023 15:49:57 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH v5 5/6] iommu: Support mm PASID 1:n with sva domains |
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On Mon, Sep 25, 2023 at 10:38:12AM +0800, Tina Zhang wrote: > Each mm bound to devices gets a PASID and corresponding sva domains > allocated in iommu_sva_bind_device(), which are referenced by iommu_mm > field of the mm. The PASID is released in __mmdrop(), while a sva domain > is released when no one is using it (the reference count is decremented > in iommu_sva_unbind_device()). However, although sva domains and their > PASID are separate objects such that their own life cycles could be > handled independently, an enqcmd use case may require releasing the > PASID in releasing the mm (i.e., once a PASID is allocated for a mm, it > will be permanently used by the mm and won't be released until the end > of mm) and only allows to drop the PASID after the sva domains are > released. To this end, mmgrab() is called in iommu_sva_domain_alloc() to > increment the mm reference count and mmdrop() is invoked in > iommu_domain_free() to decrement the mm reference count. > > Since the required info of PASID and sva domains is kept in struct > iommu_mm_data of a mm, use mm->iommu_mm field instead of the old pasid > field in mm struct. The sva domain list is protected by iommu_sva_lock. > > Besides, this patch removes mm_pasid_init(), as with the introduced > iommu_mm structure, initializing mm pasid in mm_init() is unnecessary. > > Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com> > Reviewed-by: Vasant Hegde <vasant.hegde@amd.com> > Signed-off-by: Tina Zhang <tina.zhang@intel.com> > --- > > Change in v5: > - Use smp_store_release() & READ_ONCE() in storing and loading mm's > pasid value. > > Change in v4: > - Rebase to v6.6-rc1. > > drivers/iommu/iommu-sva.c | 40 +++++++++++++++++++++++++++------------ > include/linux/iommu.h | 18 +++++++++++------- > kernel/fork.c | 1 - > 3 files changed, 39 insertions(+), 20 deletions(-)
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Jason
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