On Thu, 1 Feb 2018 01:27:38 -0500 Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> wrote: > VFIO IOMMU type1 currently upmaps IOVA pages synchronously, which requires > IOTLB flushing for every unmapping. This results in large IOTLB flushing > overhead when handling pass-through devices has a large number of mapped > IOVAs. This can be avoided by using the new IOTLB flushing interface. > > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx> > Cc: Joerg Roedel <joro@xxxxxxxxxx> > Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx> > --- > > Changes from v4 (https://lkml.org/lkml/2018/1/31/153) > * Change return type from ssize_t back to size_t since we no longer > changing IOMMU API. Also update error handling logic accordingly. > * In unmap_unpin_fast(), also sync when failing to allocate entry. > * Some code restructuring and variable renaming. > > drivers/vfio/vfio_iommu_type1.c | 128 ++++++++++++++++++++++++++++++++++++---- > 1 file changed, 117 insertions(+), 11 deletions(-) > > diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c > index e30e29a..6041530 100644 > --- a/drivers/vfio/vfio_iommu_type1.c > +++ b/drivers/vfio/vfio_iommu_type1.c > @@ -102,6 +102,13 @@ struct vfio_pfn { > atomic_t ref_count; > }; > > +struct vfio_regions { > + struct list_head list; > + dma_addr_t iova; > + phys_addr_t phys; > + size_t len; > +}; > + > #define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) \ > (!list_empty(&iommu->domain_list)) > > @@ -648,11 +655,102 @@ static int vfio_iommu_type1_unpin_pages(void *iommu_data, > return i > npage ? npage : (i > 0 ? i : -EINVAL); > } > > +static long vfio_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain, > + struct list_head *regions) > +{ > + long unlocked = 0; > + struct vfio_regions *entry, *next; > + > + iommu_tlb_sync(domain->domain); > + > + list_for_each_entry_safe(entry, next, regions, list) { > + unlocked += vfio_unpin_pages_remote(dma, > + entry->iova, > + entry->phys >> PAGE_SHIFT, > + entry->len >> PAGE_SHIFT, > + false); > + list_del(&entry->list); > + kfree(entry); > + } > + > + cond_resched(); > + > + return unlocked; > +} > + > +/* > + * Generally, VFIO needs to unpin remote pages after each IOTLB flush. > + * Therefore, when using IOTLB flush sync interface, VFIO need to keep track > + * of these regions (currently using a list). > + * > + * This value specifies maximum number of regions for each IOTLB flush sync. > + */ > +#define VFIO_IOMMU_TLB_SYNC_MAX 512 > + > +static size_t unmap_unpin_fast(struct vfio_domain *domain, > + struct vfio_dma *dma, dma_addr_t *iova, > + size_t len, phys_addr_t phys, long *unlocked, > + struct list_head *unmapped_list, > + int *unmapped_cnt) > +{ > + size_t unmapped = 0; > + struct vfio_regions *entry = kzalloc(sizeof(*entry), GFP_KERNEL); > + > + if (entry) { > + unmapped = iommu_unmap_fast(domain->domain, *iova, len); > + > + if (!unmapped) { > + kfree(entry); > + } else { > + iommu_tlb_range_add(domain->domain, *iova, unmapped); > + entry->iova = *iova; > + entry->phys = phys; > + entry->len = unmapped; > + list_add_tail(&entry->list, unmapped_list); > + > + *iova += unmapped; > + (*unmapped_cnt)++; > + } > + } > + > + /* > + * Sync if the number of fast-unmap regions hits the limit > + * or in case of errors. > + */ > + if (*unmapped_cnt >= VFIO_IOMMU_TLB_SYNC_MAX || !unmapped) { > + *unlocked += vfio_sync_unpin(dma, domain, > + unmapped_list); > + *unmapped_cnt = 0; > + } > + > + return unmapped; > +} > + > +static size_t unmap_unpin_slow(struct vfio_domain *domain, > + struct vfio_dma *dma, dma_addr_t *iova, > + size_t len, phys_addr_t phys, > + long *unlocked) > +{ > + size_t unmapped = iommu_unmap(domain->domain, *iova, len); > + > + if (unmapped) { > + *unlocked += vfio_unpin_pages_remote(dma, *iova, > + phys >> PAGE_SHIFT, > + unmapped >> PAGE_SHIFT, > + false); > + *iova += unmapped; > + cond_resched(); > + } > + return unmapped; > +} > + > static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma, > bool do_accounting) > { > dma_addr_t iova = dma->iova, end = dma->iova + dma->size; > struct vfio_domain *domain, *d; > + struct list_head unmapped_region_list; > + int unmapped_region_cnt = 0; > long unlocked = 0; > > if (!dma->size) > @@ -661,6 +759,8 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma, > if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) > return 0; > > + INIT_LIST_HEAD(&unmapped_region_list); Since I harassed Shameer about using LIST_HEAD() for the iova list extension, I feel obligated to note that it can also be used here. If you approve I'll just remove the above INIT_LIST_HEAD() and declare unmapped_region_list as LIST_HEAD(unmapped_region_list);, no need to re-send. Otherwise looks fine to me. Thanks, Alex
