Jason Wang
2022-May-09 08:02 UTC
[PATCH v1] vdpa: Do not count the pages that were already pinned in the vhost-vDPA
On Mon, May 9, 2022 at 3:15 PM Cindy Lu <lulu at redhat.com> wrote:> > We count pinned_vm as follow in vhost-vDPA > > lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; > if (npages + atomic64_read(&dev->mm->pinned_vm) > lock_limit) { > ret = -ENOMEM; > goto unlock; > } > This means if we have two vDPA devices for the same VM the pages would be counted twice > So we add a tree to save the page that counted and we will not count it again > > Signed-off-by: Cindy Lu <lulu at redhat.com> > --- > drivers/vhost/vdpa.c | 79 ++++++++++++++++++++++++++++++++++++++-- > include/linux/mm_types.h | 2 + > 2 files changed, 78 insertions(+), 3 deletions(-) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index 05f5fd2af58f..48cb5c8264b5 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -24,6 +24,9 @@ > #include <linux/vhost.h> > > #include "vhost.h" > +#include <linux/rbtree.h> > +#include <linux/interval_tree.h> > +#include <linux/interval_tree_generic.h> > > enum { > VHOST_VDPA_BACKEND_FEATURES > @@ -505,6 +508,50 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, > mutex_unlock(&d->mutex); > return r; > } > +int vhost_vdpa_add_range_ctx(struct rb_root_cached *root, u64 start, u64 last) > +{ > + struct interval_tree_node *new_node; > + > + if (last < start) > + return -EFAULT; > + > + /* If the range being mapped is [0, ULONG_MAX], split it into two entries > + * otherwise its size would overflow u64. > + */ > + if (start == 0 && last == ULONG_MAX) { > + u64 mid = last / 2; > + > + vhost_vdpa_add_range_ctx(root, start, mid); > + start = mid + 1; > + } > + > + new_node = kmalloc(sizeof(struct interval_tree_node), GFP_ATOMIC); > + if (!new_node) > + return -ENOMEM; > + > + new_node->start = start; > + new_node->last = last; > + > + interval_tree_insert(new_node, root); > + > + return 0; > +} > + > +void vhost_vdpa_del_range(struct rb_root_cached *root, u64 start, u64 last) > +{ > + struct interval_tree_node *new_node; > + > + while ((new_node = interval_tree_iter_first(root, start, last))) { > + interval_tree_remove(new_node, root); > + kfree(new_node); > + } > +} > + > +struct interval_tree_node *vhost_vdpa_search_range(struct rb_root_cached *root, > + u64 start, u64 last) > +{ > + return interval_tree_iter_first(root, start, last); > +} > > static void vhost_vdpa_pa_unmap(struct vhost_vdpa *v, u64 start, u64 last) > { > @@ -513,6 +560,7 @@ static void vhost_vdpa_pa_unmap(struct vhost_vdpa *v, u64 start, u64 last) > struct vhost_iotlb_map *map; > struct page *page; > unsigned long pfn, pinned; > + struct interval_tree_node *new_node = NULL; > > while ((map = vhost_iotlb_itree_first(iotlb, start, last)) != NULL) { > pinned = PFN_DOWN(map->size); > @@ -523,7 +571,18 @@ static void vhost_vdpa_pa_unmap(struct vhost_vdpa *v, u64 start, u64 last) > set_page_dirty_lock(page); > unpin_user_page(page); > } > - atomic64_sub(PFN_DOWN(map->size), &dev->mm->pinned_vm); > + > + new_node = vhost_vdpa_search_range(&dev->mm->root_for_vdpa, > + map->start, > + map->start + map->size - 1); > + > + if (new_node) { > + vhost_vdpa_del_range(&dev->mm->root_for_vdpa, > + map->start, > + map->start + map->size - 1); > + atomic64_sub(PFN_DOWN(map->size), &dev->mm->pinned_vm); > + } > + > vhost_iotlb_map_free(iotlb, map); > } > } > @@ -591,6 +650,7 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, u64 iova, > struct vdpa_device *vdpa = v->vdpa; > const struct vdpa_config_ops *ops = vdpa->config; > int r = 0; > + struct interval_tree_node *new_node = NULL; > > r = vhost_iotlb_add_range_ctx(dev->iotlb, iova, iova + size - 1, > pa, perm, opaque); > @@ -611,9 +671,22 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, u64 iova, > return r; > } > > - if (!vdpa->use_va) > - atomic64_add(PFN_DOWN(size), &dev->mm->pinned_vm); > + if (!vdpa->use_va) { > + new_node = vhost_vdpa_search_range(&dev->mm->root_for_vdpa, > + iova, iova + size - 1); > + > + if (new_node == 0) { > + r = vhost_vdpa_add_range_ctx(&dev->mm->root_for_vdpa, > + iova, iova + size - 1); > + if (r) { > + vhost_iotlb_del_range(dev->iotlb, iova, > + iova + size - 1); > + return r; > + } > > + atomic64_add(PFN_DOWN(size), &dev->mm->pinned_vm); > + }This seems not sufficient, consider: vhost-vDPA-A: add [A, B) vhost-vDPA-B: add [A, C) (C>B) We lose the accounting for [B, C)?> + } > return 0; > } > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 5140e5feb486..46eaa6d0560b 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -634,6 +634,8 @@ struct mm_struct { > #ifdef CONFIG_IOMMU_SUPPORT > u32 pasid; > #endif > + struct rb_root_cached root_for_vdpa; > +Let's avoid touching mm_structure unless it's a must. We can allocate something like vhost_mm if needed during SET_OWNER. Thanks> } __randomize_layout; > > /* > -- > 2.34.1 >