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>

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 30402e6..eabcf18 100644 (file)
--- 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 =