From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch adds ANY_LAYOUT prerequisites logic for accepting a set of
protection + data payloads via iov_iter. Also includes helpers for
calcuating SGLs + invoking vhost_scsi_map_to_sgl() with a known number
of iovecs.
Required by ANY_LAYOUT processing when struct iovec may be offset into
the first outgoing virtio-scsi request header.
v2 changes:
- Clear ->tvc_sgl_count for vhost_scsi_mapal failure
- Make vhost_scsi_mapal + vhost_scsi_calc_sgls accept max_niov
- Minor cleanups
v3 changes:
- Update vhost_scsi_mapal + friends to use iov_iter
- Move iov_iter sanity checks into vhost_scsi_calc_sgls
- Convert vhost_scsi_calc_sgls() to iov_iter_npages()
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/vhost/scsi.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 93 insertions(+)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index c3b12b3..7dfff15 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -914,6 +914,99 @@ vhost_scsi_map_iov_to_prot(struct tcm_vhost_cmd *cmd,
return 0;
}
+static int
+vhost_scsi_calc_sgls(struct iov_iter *iter, size_t bytes, int max_sgls)
+{
+ int sgl_count = 0;
+
+ if (!iter || !iter->iov) {
+ pr_err("%s: iter->iov is NULL, but expected bytes: %zu"
+ " present\n", __func__, bytes);
+ return -EINVAL;
+ }
+
+ sgl_count = iov_iter_npages(iter, 0xffff);
+ if (sgl_count > max_sgls) {
+ pr_err("%s: requested sgl_count: %d exceeds pre-allocated"
+ " max_sgls: %d\n", __func__, sgl_count, max_sgls);
+ return -EINVAL;
+ }
+ return sgl_count;
+}
+
+static int
+vhost_scsi_iov_to_sgl(struct tcm_vhost_cmd *cmd, bool write,
+ struct iov_iter *iter, struct scatterlist *sg,
+ int sg_count)
+{
+ size_t off = iter->iov_offset;
+ int i, ret;
+
+ for (i = 0; i < iter->nr_segs; i++) {
+ void __user *base = iter->iov[i].iov_base + off;
+ size_t len = iter->iov[i].iov_len - off;
+
+ ret = vhost_scsi_map_to_sgl(cmd, base, len, sg, write);
+ if (ret < 0) {
+ for (i = 0; i < sg_count; i++) {
+ struct page *page = sg_page(&sg[i]);
+ if (page)
+ put_page(page);
+ }
+ return ret;
+ }
+ sg += ret;
+ off = 0;
+ }
+ return 0;
+}
+
+static int
+vhost_scsi_mapal(struct tcm_vhost_cmd *cmd,
+ size_t prot_bytes, struct iov_iter *prot_iter,
+ size_t data_bytes, struct iov_iter *data_iter)
+{
+ int sgl_count, ret;
+ bool write = (cmd->tvc_data_direction == DMA_FROM_DEVICE);
+
+ if (prot_bytes) {
+ sgl_count = vhost_scsi_calc_sgls(prot_iter, prot_bytes,
+ TCM_VHOST_PREALLOC_PROT_SGLS);
+ if (sgl_count < 0)
+ return sgl_count;
+
+ sg_init_table(cmd->tvc_prot_sgl, sgl_count);
+ cmd->tvc_prot_sgl_count = sgl_count;
+ pr_debug("%s prot_sg %p prot_sgl_count %u\n", __func__,
+ cmd->tvc_prot_sgl, cmd->tvc_prot_sgl_count);
+
+ ret = vhost_scsi_iov_to_sgl(cmd, write, prot_iter,
+ cmd->tvc_prot_sgl,
+ cmd->tvc_prot_sgl_count);
+ if (ret < 0) {
+ cmd->tvc_prot_sgl_count = 0;
+ return ret;
+ }
+ }
+ sgl_count = vhost_scsi_calc_sgls(data_iter, data_bytes,
+ TCM_VHOST_PREALLOC_SGLS);
+ if (sgl_count < 0)
+ return sgl_count;
+
+ sg_init_table(cmd->tvc_sgl, sgl_count);
+ cmd->tvc_sgl_count = sgl_count;
+ pr_debug("%s data_sg %p data_sgl_count %u\n", __func__,
+ cmd->tvc_sgl, cmd->tvc_sgl_count);
+
+ ret = vhost_scsi_iov_to_sgl(cmd, write, data_iter,
+ cmd->tvc_sgl, cmd->tvc_sgl_count);
+ if (ret < 0) {
+ cmd->tvc_sgl_count = 0;
+ return ret;
+ }
+ return 0;
+}
+
static void tcm_vhost_submission_work(struct work_struct *work)
{
struct tcm_vhost_cmd *cmd =
--
1.9.1
--
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