vhost/scsi: Add T10 PI IOV -> SGL memory mapping logic

This patch adds vhost_scsi_map_iov_to_prot() to perform the mapping of
T10 data integrity memory between virtio iov + struct scatterlist using
get_user_pages_fast() following existing code.

As with vhost_scsi_map_iov_to_sgl(), this does sanity checks against the
total prot_sgl_count vs. pre-allocated SGLs, and loops across protection
iovs using vhost_scsi_map_to_sgl() to perform the actual memory mapping.

Also update tcm_vhost_release_cmd() to release associated tvc_prot_sgl[]
struct page.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Sagi Grimberg <sagig@dev.mellanox.co.il>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 47 insertions, 1 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 30402e618078..eabcf1875831 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -80,6 +80,7 @@ struct tcm_vhost_cmd {
         u64 tvc_tag;
         /* The number of scatterlists associated with this cmd */
         u32 tvc_sgl_count;
+        u32 tvc_prot_sgl_count;
         /* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
         u32 tvc_lun;
         /* Pointer to the SGL formatted memory from virtio-scsi */
@@ -458,12 +459,16 @@ static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
         struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
                                 struct tcm_vhost_cmd, tvc_se_cmd);
         struct se_session *se_sess = se_cmd->se_sess;
+        int i;
 
         if (tv_cmd->tvc_sgl_count) {
-                u32 i;
                 for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
                         put_page(sg_page(&tv_cmd->tvc_sgl[i]));
         }
+        if (tv_cmd->tvc_prot_sgl_count) {
+                for (i = 0; i < tv_cmd->tvc_prot_sgl_count; i++)
+                        put_page(sg_page(&tv_cmd->tvc_prot_sgl[i]));
+        }
 
         tcm_vhost_put_inflight(tv_cmd->inflight);
         percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);
@@ -861,6 +866,47 @@ vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,
         return 0;
 }
 
+static int
+vhost_scsi_map_iov_to_prot(struct tcm_vhost_cmd *cmd,
+                           struct iovec *iov,
+                           int niov,
+                           bool write)
+{
+        struct scatterlist *prot_sg = cmd->tvc_prot_sgl;
+        unsigned int prot_sgl_count = 0;
+        int ret, i;
+
+        for (i = 0; i < niov; i++)
+                prot_sgl_count += iov_num_pages(&iov[i]);
+
+        if (prot_sgl_count > TCM_VHOST_PREALLOC_PROT_SGLS) {
+                pr_err("vhost_scsi_map_iov_to_prot() sgl_count: %u greater than"
+                        " preallocated TCM_VHOST_PREALLOC_PROT_SGLS: %u\n",
+                        prot_sgl_count, TCM_VHOST_PREALLOC_PROT_SGLS);
+                return -ENOBUFS;
+        }
+
+        pr_debug("%s prot_sg %p prot_sgl_count %u\n", __func__,
+                 prot_sg, prot_sgl_count);
+        sg_init_table(prot_sg, prot_sgl_count);
+        cmd->tvc_prot_sgl_count = prot_sgl_count;
+
+        for (i = 0; i < niov; i++) {
+                ret = vhost_scsi_map_to_sgl(cmd, prot_sg, prot_sgl_count, &iov[i],
+                                            cmd->tvc_upages, write);
+                if (ret < 0) {
+                        for (i = 0; i < cmd->tvc_prot_sgl_count; i++)
+                                put_page(sg_page(&cmd->tvc_prot_sgl[i]));
+
+                        cmd->tvc_prot_sgl_count = 0;
+                        return ret;
+                }
+                prot_sg += ret;
+                prot_sgl_count -= ret;
+        }
+        return 0;
+}
+
 static void tcm_vhost_submission_work(struct work_struct *work)
 {
         struct tcm_vhost_cmd *cmd =