On Sun, Jun 26, 2022 at 05:04:08PM +0800, Cindy Lu 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.
>
> Add vdpa_mem_tree to saved the mem that already counted.
> use a hlist to saved the root for vdpa_mem_tree.
>
> Signed-off-by: Cindy Lu <lulu@xxxxxxxxxx>
> ---
> drivers/vhost/vhost.c | 63 +++++++++++++++++++++++++++++++++++++++++++
> drivers/vhost/vhost.h | 1 +
> 2 files changed, 64 insertions(+)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 40097826cff0..4ca8b1ed944b 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -32,6 +32,8 @@
> #include <linux/kcov.h>
>
> #include "vhost.h"
> +#include <linux/hashtable.h>
> +#include <linux/jhash.h>
>
> static ushort max_mem_regions = 64;
> module_param(max_mem_regions, ushort, 0444);
> @@ -49,6 +51,14 @@ enum {
> #define vhost_used_event(vq) ((__virtio16 __user *)&vq->avail->ring[vq->num])
> #define vhost_avail_event(vq) ((__virtio16 __user *)&vq->used->ring[vq->num])
>
> +struct vhost_vdpa_rbtree_node {
> + struct hlist_node node;
> + struct rb_root_cached vdpa_mem_tree;
> + struct mm_struct *mm_using;
> +};
> +static DECLARE_HASHTABLE(vhost_vdpa_rbtree_hlist, 8);
> +int vhost_vdpa_rbtree_hlist_status;
> +
> #ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
> static void vhost_disable_cross_endian(struct vhost_virtqueue *vq)
> {
Are you trying to save some per-mm information here?
Can't we just add it to mm_struct?
> @@ -571,6 +581,51 @@ static void vhost_detach_mm(struct vhost_dev *dev)
> dev->mm = NULL;
> }
>
> +struct rb_root_cached *vhost_vdpa_get_mem_tree(struct mm_struct *mm)
> +{
> + struct vhost_vdpa_rbtree_node *rbtree_root = NULL;
> + struct rb_root_cached *vdpa_tree;
> + u32 key;
> +
> + /* No hased table, init one */
> + if (vhost_vdpa_rbtree_hlist_status == 0) {
> + hash_init(vhost_vdpa_rbtree_hlist);
> + vhost_vdpa_rbtree_hlist_status = 1;
> + }
> +
> + key = jhash_1word((u64)mm, JHASH_INITVAL);
> + hash_for_each_possible(vhost_vdpa_rbtree_hlist, rbtree_root, node,
> + key) {
> + if (rbtree_root->mm_using == mm)
> + return &(rbtree_root->vdpa_mem_tree);
> + }
> + rbtree_root = kmalloc(sizeof(*rbtree_root), GFP_KERNEL);
> + if (!rbtree_root)
> + return NULL;
> + rbtree_root->mm_using = mm;
> + rbtree_root->vdpa_mem_tree = RB_ROOT_CACHED;
> + hash_add(vhost_vdpa_rbtree_hlist, &rbtree_root->node, key);
> + vdpa_tree = &(rbtree_root->vdpa_mem_tree);
> + return vdpa_tree;
> +}
> +
> +void vhost_vdpa_relase_mem_tree(struct mm_struct *mm)
> +{
> + struct vhost_vdpa_rbtree_node *rbtree_root = NULL;
> + u32 key;
> +
> + key = jhash_1word((u64)mm, JHASH_INITVAL);
> +
> + /* No hased table, init one */
> + hash_for_each_possible(vhost_vdpa_rbtree_hlist, rbtree_root, node,
> + key) {
> + if (rbtree_root->mm_using == mm) {
> + hash_del(&rbtree_root->node);
> + kfree(rbtree_root);
> + }
> + }
> +}
> +
> /* Caller should have device mutex */
> long vhost_dev_set_owner(struct vhost_dev *dev)
> {
> @@ -605,6 +660,11 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
> err = vhost_dev_alloc_iovecs(dev);
> if (err)
> goto err_cgroup;
> + dev->vdpa_mem_tree = vhost_vdpa_get_mem_tree(dev->mm);
> + if (dev->vdpa_mem_tree == NULL) {
> + err = -ENOMEM;
> + goto err_cgroup;
> + }
>
> return 0;
> err_cgroup:
> @@ -613,6 +673,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
> dev->worker = NULL;
> }
> err_worker:
> + vhost_vdpa_relase_mem_tree(dev->mm);
> vhost_detach_mm(dev);
> dev->kcov_handle = 0;
> err_mm:
> @@ -710,6 +771,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
> dev->worker = NULL;
> dev->kcov_handle = 0;
> }
> +
> + vhost_vdpa_relase_mem_tree(dev->mm);
> vhost_detach_mm(dev);
> }
> EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index d9109107af08..84de33de3abf 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -160,6 +160,7 @@ struct vhost_dev {
> int byte_weight;
> u64 kcov_handle;
> bool use_worker;
> + struct rb_root_cached *vdpa_mem_tree;
> int (*msg_handler)(struct vhost_dev *dev, u32 asid,
> struct vhost_iotlb_msg *msg);
> };
> --
> 2.34.3
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