[PATCH v2 13/17] hw/block/nvme: add support for sgl bit bucket descriptor

[Klaus Jensen <its@irrelevant.dk>]

From: Gollu Appalanaidu <anaidu.gollu@samsung.com>

This adds support for SGL descriptor type 0x1 (bit bucket descriptor).
See the NVM Express v1.3d specification, Section 4.4 ("Scatter Gather
List (SGL)").

Signed-off-by: Gollu Appalanaidu <anaidu.gollu@samsung.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/block/nvme.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index e01b4b22882e..d2e211c7cbc2 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -430,6 +430,10 @@ static uint16_t nvme_map_sgl_data(NvmeCtrl *n, QEMUSGList *qsg,
         uint8_t type = NVME_SGL_TYPE(segment[i].type);
 
         switch (type) {
+        case NVME_SGL_DESCR_TYPE_BIT_BUCKET:
+            if (req->cmd.opcode == NVME_CMD_WRITE) {
+                continue;
+            }
         case NVME_SGL_DESCR_TYPE_DATA_BLOCK:
             break;
         case NVME_SGL_DESCR_TYPE_SEGMENT:
@@ -440,6 +444,7 @@ static uint16_t nvme_map_sgl_data(NvmeCtrl *n, QEMUSGList *qsg,
         }
 
         dlen = le32_to_cpu(segment[i].len);
+
         if (!dlen) {
             continue;
         }
@@ -460,6 +465,11 @@ static uint16_t nvme_map_sgl_data(NvmeCtrl *n, QEMUSGList *qsg,
         }
 
         trans_len = MIN(*len, dlen);
+
+        if (type == NVME_SGL_DESCR_TYPE_BIT_BUCKET) {
+            goto next;
+        }
+
         addr = le64_to_cpu(segment[i].addr);
 
         if (UINT64_MAX - addr < dlen) {
@@ -471,6 +481,7 @@ static uint16_t nvme_map_sgl_data(NvmeCtrl *n, QEMUSGList *qsg,
             return status;
         }
 
+next:
         *len -= trans_len;
     }
 
@@ -540,7 +551,8 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, QEMUSGList *qsg, QEMUIOVector *iov,
         seg_len = le32_to_cpu(sgld->len);
 
         /* check the length of the (Last) Segment descriptor */
-        if (!seg_len || seg_len & 0xf) {
+        if ((!seg_len || seg_len & 0xf) &&
+            (NVME_SGL_TYPE(sgld->type) != NVME_SGL_DESCR_TYPE_BIT_BUCKET)) {
             return NVME_INVALID_SGL_SEG_DESCR | NVME_DNR;
         }
 
@@ -577,19 +589,27 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, QEMUSGList *qsg, QEMUIOVector *iov,
 
         last_sgld = &segment[nsgld - 1];
 
-        /* if the segment ends with a Data Block, then we are done */
-        if (NVME_SGL_TYPE(last_sgld->type) == NVME_SGL_DESCR_TYPE_DATA_BLOCK) {
+        /*
+         * If the segment ends with a Data Block or Bit Bucket Descriptor Type,
+         * then we are done.
+         */
+        switch (NVME_SGL_TYPE(last_sgld->type)) {
+        case NVME_SGL_DESCR_TYPE_DATA_BLOCK:
+        case NVME_SGL_DESCR_TYPE_BIT_BUCKET:
             status = nvme_map_sgl_data(n, qsg, iov, segment, nsgld, &len, req);
             if (status) {
                 goto unmap;
             }
 
             goto out;
+
+        default:
+            break;
         }
 
         /*
-         * If the last descriptor was not a Data Block, then the current
-         * segment must not be a Last Segment.
+         * If the last descriptor was not a Data Block or Bit Bucket, then the
+         * current segment must not be a Last Segment.
          */
         if (NVME_SGL_TYPE(sgld->type) == NVME_SGL_DESCR_TYPE_LAST_SEGMENT) {
             status = NVME_INVALID_SGL_SEG_DESCR | NVME_DNR;
@@ -2654,7 +2674,8 @@ static void nvme_init_ctrl(NvmeCtrl *n, PCIDevice *pci_dev)
     id->nn = cpu_to_le32(n->num_namespaces);
     id->oncs = cpu_to_le16(NVME_ONCS_WRITE_ZEROES | NVME_ONCS_TIMESTAMP |
                            NVME_ONCS_FEATURES);
-    id->sgls = cpu_to_le32(NVME_CTRL_SGLS_SUPPORT_NO_ALIGN);
+    id->sgls = cpu_to_le32(NVME_CTRL_SGLS_SUPPORT_NO_ALIGN |
+                           NVME_CTRL_SGLS_BITBUCKET);
 
     subnqn = g_strdup_printf("nqn.2019-08.org.qemu:%s", n->params.serial);
     strpadcpy((char *)id->subnqn, sizeof(id->subnqn), subnqn, '\0');
-- 
2.28.0