This patch introduces the support of ASID based IOTLB by tagging IOTLB
with a unique ASID. This is a must for supporting ASID based vhost
IOTLB API by the following patches.

IOTLB were stored in a hlist and new IOTLB will be allocated when a
new ASID is seen via IOTLB API and destoryed when there's no mapping
associated with an ASID.

Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 drivers/vhost/vdpa.c | 94 +++++++++++++++++++++++++++++++++-----------
 1 file changed, 72 insertions(+), 22 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 6552987544d7..1ba7e95619b5 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -34,13 +34,21 @@ enum {
 
 #define VHOST_VDPA_DEV_MAX (1U << MINORBITS)
 
+#define VHOST_VDPA_IOTLB_BUCKETS 16
+
+struct vhost_vdpa_as {
+       struct hlist_node hash_link;
+       struct vhost_iotlb iotlb;
+       u32 id;
+};
+
 struct vhost_vdpa {
        struct vhost_dev vdev;
        struct iommu_domain *domain;
        struct vhost_virtqueue *vqs;
        struct completion completion;
        struct vdpa_device *vdpa;
-       struct vhost_iotlb *iotlb;
+       struct hlist_head as[VHOST_VDPA_IOTLB_BUCKETS];
        struct device dev;
        struct cdev cdev;
        atomic_t opened;
@@ -49,12 +57,64 @@ struct vhost_vdpa {
        int minor;
        struct eventfd_ctx *config_ctx;
        int in_batch;
+       int used_as;
 };
 
 static DEFINE_IDA(vhost_vdpa_ida);
 
 static dev_t vhost_vdpa_major;
 
+static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32 asid)
+{
+       struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
+       struct vhost_vdpa_as *as;
+
+       hlist_for_each_entry(as, head, hash_link)
+               if (as->id == asid)
+                       return as;
+
+       return NULL;
+}
+
+static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 
asid)
+{
+       struct hlist_head *head = &v->as[asid % VHOST_VDPA_IOTLB_BUCKETS];
+       struct vhost_vdpa_as *as;
+
+       if (asid_to_as(v, asid))
+               return NULL;
+
+       as = kmalloc(sizeof(*as), GFP_KERNEL);
+       if (!as)
+               return NULL;
+
+       vhost_iotlb_init(&as->iotlb, 0, 0);
+       as->id = asid;
+       hlist_add_head(&as->hash_link, head);
+       ++v->used_as;
+
+       return as;
+}
+
+static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
+{
+       struct vhost_vdpa_as *as = asid_to_as(v, asid);
+
+       /* Remove default address space is not allowed */
+       if (asid == 0)
+               return -EINVAL;
+
+       if (!as)
+               return -EINVAL;
+
+       hlist_del(&as->hash_link);
+       vhost_iotlb_reset(&as->iotlb);
+       kfree(as);
+       --v->used_as;
+
+       return 0;
+}
+
 static void handle_vq_kick(struct vhost_work *work)
 {
        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
@@ -513,15 +573,6 @@ static void vhost_vdpa_iotlb_unmap(struct vhost_vdpa *v,
        }
 }
 
-static void vhost_vdpa_iotlb_free(struct vhost_vdpa *v)
-{
-       struct vhost_iotlb *iotlb = v->iotlb;
-
-       vhost_vdpa_iotlb_unmap(v, iotlb, 0ULL, 0ULL - 1);
-       kfree(v->iotlb);
-       v->iotlb = NULL;
-}
-
 static int perm_to_iommu_flags(u32 perm)
 {
        int flags = 0;
@@ -681,7 +732,8 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev 
*dev, u32 asid,
        struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
        struct vdpa_device *vdpa = v->vdpa;
        const struct vdpa_config_ops *ops = vdpa->config;
-       struct vhost_iotlb *iotlb = v->iotlb;
+       struct vhost_vdpa_as *as = asid_to_as(v, 0);
+       struct vhost_iotlb *iotlb = &as->iotlb;
        int r = 0;
 
        if (asid != 0)
@@ -775,6 +827,7 @@ static void vhost_vdpa_cleanup(struct vhost_vdpa *v)
 {
        vhost_dev_cleanup(&v->vdev);
        kfree(v->vdev.vqs);
+       vhost_vdpa_remove_as(v, 0);
 }
 
 static int vhost_vdpa_open(struct inode *inode, struct file *filep)
@@ -807,23 +860,18 @@ static int vhost_vdpa_open(struct inode *inode, struct 
file *filep)
        vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false,
                       vhost_vdpa_process_iotlb_msg);
 
-       dev->iotlb = vhost_iotlb_alloc(0, 0);
-       if (!dev->iotlb) {
-               r = -ENOMEM;
-               goto err_init_iotlb;
-       }
+       if (!vhost_vdpa_alloc_as(v, 0))
+               goto err_alloc_as;
 
        r = vhost_vdpa_alloc_domain(v);
        if (r)
-               goto err_alloc_domain;
+               goto err_alloc_as;
 
        filep->private_data = v;
 
        return 0;
 
-err_alloc_domain:
-       vhost_vdpa_iotlb_free(v);
-err_init_iotlb:
+err_alloc_as:
        vhost_vdpa_cleanup(v);
 err:
        atomic_dec(&v->opened);
@@ -851,7 +899,6 @@ static int vhost_vdpa_release(struct inode *inode, struct 
file *filep)
        filep->private_data = NULL;
        vhost_vdpa_reset(v);
        vhost_dev_stop(&v->vdev);
-       vhost_vdpa_iotlb_free(v);
        vhost_vdpa_free_domain(v);
        vhost_vdpa_config_put(v);
        vhost_vdpa_clean_irq(v);
@@ -950,7 +997,7 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
        const struct vdpa_config_ops *ops = vdpa->config;
        struct vhost_vdpa *v;
        int minor;
-       int r;
+       int i, r;
 
        /* Only support 1 address space */
        if (vdpa->ngroups != 1)
@@ -1002,6 +1049,9 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
        init_completion(&v->completion);
        vdpa_set_drvdata(vdpa, v);
 
+       for (i = 0; i < VHOST_VDPA_IOTLB_BUCKETS; i++)
+               INIT_HLIST_HEAD(&v->as[i]);
+
        return 0;
 
 err:
-- 
2.20.1

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