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vhost/scsi: Add pre-allocation for tv_cmd SGL + upages memory
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This patch adds support for pre-allocation of per tv_cmd descriptor
scatterlist + user-space page pointer memory using se_sess->sess_cmd_map
within tcm_vhost_make_nexus() code.

This includes sanity checks within vhost_scsi_map_to_sgl()
to reject I/O that exceeds these initial hardcoded values, and
the necessary cleanup in tcm_vhost_make_nexus() failure path +
tcm_vhost_drop_nexus().

v3 changes:
  - Rebase to v3.11-rc5 code

Cc: Michael S. Tsirkin <[email protected]>
Cc: Asias He <[email protected]>
Cc: Kent Overstreet <[email protected]>
Reviewed-by: Asias He <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Nicholas Bellinger <[email protected]>
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Nicholas Bellinger committed Sep 9, 2013
1 parent 4824d3b commit 3aee26b
Showing 1 changed file with 80 additions and 19 deletions.
99 changes: 80 additions & 19 deletions drivers/vhost/scsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,8 @@
#define TCM_VHOST_NAMELEN 256
#define TCM_VHOST_MAX_CDB_SIZE 32
#define TCM_VHOST_DEFAULT_TAGS 256
#define TCM_VHOST_PREALLOC_SGLS 2048
#define TCM_VHOST_PREALLOC_PAGES 2048

struct vhost_scsi_inflight {
/* Wait for the flush operation to finish */
Expand All @@ -81,6 +83,7 @@ struct tcm_vhost_cmd {
u32 tvc_lun;
/* Pointer to the SGL formatted memory from virtio-scsi */
struct scatterlist *tvc_sgl;
struct page **tvc_upages;
/* Pointer to response */
struct virtio_scsi_cmd_resp __user *tvc_resp;
/* Pointer to vhost_scsi for our device */
Expand Down Expand Up @@ -458,8 +461,6 @@ static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
u32 i;
for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
put_page(sg_page(&tv_cmd->tvc_sgl[i]));

kfree(tv_cmd->tvc_sgl);
}

tcm_vhost_put_inflight(tv_cmd->inflight);
Expand Down Expand Up @@ -716,6 +717,8 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq,
struct tcm_vhost_cmd *cmd;
struct tcm_vhost_nexus *tv_nexus;
struct se_session *se_sess;
struct scatterlist *sg;
struct page **pages;
int tag;

tv_nexus = tpg->tpg_nexus;
Expand All @@ -727,8 +730,12 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq,

tag = percpu_ida_alloc(&se_sess->sess_tag_pool, GFP_KERNEL);
cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[tag];
sg = cmd->tvc_sgl;
pages = cmd->tvc_upages;
memset(cmd, 0, sizeof(struct tcm_vhost_cmd));

cmd->tvc_sgl = sg;
cmd->tvc_upages = pages;
cmd->tvc_se_cmd.map_tag = tag;
cmd->tvc_tag = v_req->tag;
cmd->tvc_task_attr = v_req->task_attr;
Expand All @@ -746,7 +753,8 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq,
* Returns the number of scatterlist entries used or -errno on error.
*/
static int
vhost_scsi_map_to_sgl(struct scatterlist *sgl,
vhost_scsi_map_to_sgl(struct tcm_vhost_cmd *tv_cmd,
struct scatterlist *sgl,
unsigned int sgl_count,
struct iovec *iov,
int write)
Expand All @@ -758,13 +766,25 @@ vhost_scsi_map_to_sgl(struct scatterlist *sgl,
struct page **pages;
int ret, i;

if (sgl_count > TCM_VHOST_PREALLOC_SGLS) {
pr_err("vhost_scsi_map_to_sgl() psgl_count: %u greater than"
" preallocated TCM_VHOST_PREALLOC_SGLS: %u\n",
sgl_count, TCM_VHOST_PREALLOC_SGLS);
return -ENOBUFS;
}

pages_nr = iov_num_pages(iov);
if (pages_nr > sgl_count)
return -ENOBUFS;

pages = kmalloc(pages_nr * sizeof(struct page *), GFP_KERNEL);
if (!pages)
return -ENOMEM;
if (pages_nr > TCM_VHOST_PREALLOC_PAGES) {
pr_err("vhost_scsi_map_to_sgl() pages_nr: %u greater than"
" preallocated TCM_VHOST_PREALLOC_PAGES: %u\n",
pages_nr, TCM_VHOST_PREALLOC_PAGES);
return -ENOBUFS;
}

pages = tv_cmd->tvc_upages;

ret = get_user_pages_fast((unsigned long)ptr, pages_nr, write, pages);
/* No pages were pinned */
Expand All @@ -789,7 +809,6 @@ vhost_scsi_map_to_sgl(struct scatterlist *sgl,
}

out:
kfree(pages);
return ret;
}

Expand All @@ -813,24 +832,20 @@ vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,

/* TODO overflow checking */

sg = kmalloc(sizeof(cmd->tvc_sgl[0]) * sgl_count, GFP_ATOMIC);
if (!sg)
return -ENOMEM;
pr_debug("%s sg %p sgl_count %u is_err %d\n", __func__,
sg, sgl_count, !sg);
sg = cmd->tvc_sgl;
pr_debug("%s sg %p sgl_count %u\n", __func__, sg, sgl_count);
sg_init_table(sg, sgl_count);

cmd->tvc_sgl = sg;
cmd->tvc_sgl_count = sgl_count;

pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
for (i = 0; i < niov; i++) {
ret = vhost_scsi_map_to_sgl(sg, sgl_count, &iov[i], write);
ret = vhost_scsi_map_to_sgl(cmd, sg, sgl_count, &iov[i],
write);
if (ret < 0) {
for (i = 0; i < cmd->tvc_sgl_count; i++)
put_page(sg_page(&cmd->tvc_sgl[i]));
kfree(cmd->tvc_sgl);
cmd->tvc_sgl = NULL;

cmd->tvc_sgl_count = 0;
return ret;
}
Expand Down Expand Up @@ -1660,11 +1675,31 @@ static void tcm_vhost_drop_nodeacl(struct se_node_acl *se_acl)
kfree(nacl);
}

static void tcm_vhost_free_cmd_map_res(struct tcm_vhost_nexus *nexus,
struct se_session *se_sess)
{
struct tcm_vhost_cmd *tv_cmd;
unsigned int i;

if (!se_sess->sess_cmd_map)
return;

for (i = 0; i < TCM_VHOST_DEFAULT_TAGS; i++) {
tv_cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[i];

kfree(tv_cmd->tvc_sgl);
kfree(tv_cmd->tvc_upages);
}
}

static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,
const char *name)
{
struct se_portal_group *se_tpg;
struct se_session *se_sess;
struct tcm_vhost_nexus *tv_nexus;
struct tcm_vhost_cmd *tv_cmd;
unsigned int i;

mutex_lock(&tpg->tv_tpg_mutex);
if (tpg->tpg_nexus) {
Expand Down Expand Up @@ -1692,6 +1727,26 @@ static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,
kfree(tv_nexus);
return -ENOMEM;
}
se_sess = tv_nexus->tvn_se_sess;
for (i = 0; i < TCM_VHOST_DEFAULT_TAGS; i++) {
tv_cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[i];

tv_cmd->tvc_sgl = kzalloc(sizeof(struct scatterlist) *
TCM_VHOST_PREALLOC_SGLS, GFP_KERNEL);
if (!tv_cmd->tvc_sgl) {
mutex_unlock(&tpg->tv_tpg_mutex);
pr_err("Unable to allocate tv_cmd->tvc_sgl\n");
goto out;
}

tv_cmd->tvc_upages = kzalloc(sizeof(struct page *) *
TCM_VHOST_PREALLOC_PAGES, GFP_KERNEL);
if (!tv_cmd->tvc_upages) {
mutex_unlock(&tpg->tv_tpg_mutex);
pr_err("Unable to allocate tv_cmd->tvc_upages\n");
goto out;
}
}
/*
* Since we are running in 'demo mode' this call with generate a
* struct se_node_acl for the tcm_vhost struct se_portal_group with
Expand All @@ -1703,9 +1758,7 @@ static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,
mutex_unlock(&tpg->tv_tpg_mutex);
pr_debug("core_tpg_check_initiator_node_acl() failed"
" for %s\n", name);
transport_free_session(tv_nexus->tvn_se_sess);
kfree(tv_nexus);
return -ENOMEM;
goto out;
}
/*
* Now register the TCM vhost virtual I_T Nexus as active with the
Expand All @@ -1717,6 +1770,12 @@ static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,

mutex_unlock(&tpg->tv_tpg_mutex);
return 0;

out:
tcm_vhost_free_cmd_map_res(tv_nexus, se_sess);
transport_free_session(se_sess);
kfree(tv_nexus);
return -ENOMEM;
}

static int tcm_vhost_drop_nexus(struct tcm_vhost_tpg *tpg)
Expand Down Expand Up @@ -1756,6 +1815,8 @@ static int tcm_vhost_drop_nexus(struct tcm_vhost_tpg *tpg)
pr_debug("TCM_vhost_ConfigFS: Removing I_T Nexus to emulated"
" %s Initiator Port: %s\n", tcm_vhost_dump_proto_id(tpg->tport),
tv_nexus->tvn_se_sess->se_node_acl->initiatorname);

tcm_vhost_free_cmd_map_res(tv_nexus, se_sess);
/*
* Release the SCSI I_T Nexus to the emulated vhost Target Port
*/
Expand Down

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