vhost/scsi: Add preallocation of protection SGLs

This patch updates tcm_vhost_make_nexus() to pre-allocate per descriptor
tcm_vhost_cmd->tvc_prot_sgl[] used to expose protection SGLs from within
virtio-scsi guest memory to vhost-scsi.

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>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index ae434db2d384..30402e618078 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -58,6 +58,7 @@
 #define TCM_VHOST_DEFAULT_TAGS 256
 #define TCM_VHOST_PREALLOC_SGLS 2048
 #define TCM_VHOST_PREALLOC_UPAGES 2048
+#define TCM_VHOST_PREALLOC_PROT_SGLS 512
 
 struct vhost_scsi_inflight {
         /* Wait for the flush operation to finish */
@@ -83,6 +84,7 @@ struct tcm_vhost_cmd {
         u32 tvc_lun;
         /* Pointer to the SGL formatted memory from virtio-scsi */
         struct scatterlist *tvc_sgl;
+        struct scatterlist *tvc_prot_sgl;
         struct page **tvc_upages;
         /* Pointer to response */
         struct virtio_scsi_cmd_resp __user *tvc_resp;
@@ -722,7 +724,7 @@ 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 scatterlist *sg, *prot_sg;
         struct page **pages;
         int tag;
 
@@ -741,10 +743,12 @@ vhost_scsi_get_tag(struct vhost_virtqueue *vq,
 
         cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[tag];
         sg = cmd->tvc_sgl;
+        prot_sg = cmd->tvc_prot_sgl;
         pages = cmd->tvc_upages;
         memset(cmd, 0, sizeof(struct tcm_vhost_cmd));
 
         cmd->tvc_sgl = sg;
+        cmd->tvc_prot_sgl = prot_sg;
         cmd->tvc_upages = pages;
         cmd->tvc_se_cmd.map_tag = tag;
         cmd->tvc_tag = v_req->tag;
@@ -1703,6 +1707,7 @@ static void tcm_vhost_free_cmd_map_res(struct tcm_vhost_nexus *nexus,
                 tv_cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[i];
 
                 kfree(tv_cmd->tvc_sgl);
+                kfree(tv_cmd->tvc_prot_sgl);
                 kfree(tv_cmd->tvc_upages);
         }
 }
@@ -1762,6 +1767,14 @@ static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,
                         pr_err("Unable to allocate tv_cmd->tvc_upages\n");
                         goto out;
                 }
+
+                tv_cmd->tvc_prot_sgl = kzalloc(sizeof(struct scatterlist) *
+                                        TCM_VHOST_PREALLOC_PROT_SGLS, GFP_KERNEL);
+                if (!tv_cmd->tvc_prot_sgl) {
+                        mutex_unlock(&tpg->tv_tpg_mutex);
+                        pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n");
+                        goto out;
+                }
         }
         /*
          * Since we are running in 'demo mode' this call with generate a