[PATCH v2 15/16] hw/block/nvme: use preallocated qsg/iov in nvme_dma_prp

[Klaus Jensen <its@irrelevant.dk>]

From: Klaus Jensen <k.jensen@samsung.com>

Since clean up of the request qsg/iov is now always done post-use, there
is no need to use a stack-allocated qsg/iov in nvme_dma_prp.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Acked-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 hw/block/nvme.c | 41 ++++++++++++++++++-----------------------
 1 file changed, 18 insertions(+), 23 deletions(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 045dd55376a5..55b1a68ced8c 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -381,50 +381,45 @@ static uint16_t nvme_map_prp(QEMUSGList *qsg, QEMUIOVector *iov, uint64_t prp1,
 }
 
 static uint16_t nvme_dma_prp(NvmeCtrl *n, uint8_t *ptr, uint32_t len,
-                             uint64_t prp1, uint64_t prp2, DMADirection dir)
+                             uint64_t prp1, uint64_t prp2, DMADirection dir,
+                             NvmeRequest *req)
 {
-    QEMUSGList qsg;
-    QEMUIOVector iov;
     uint16_t status = NVME_SUCCESS;
 
-    status = nvme_map_prp(&qsg, &iov, prp1, prp2, len, n);
+    status = nvme_map_prp(&req->qsg, &req->iov, prp1, prp2, len, n);
     if (status) {
         return status;
     }
 
     /* assert that only one of qsg and iov carries data */
-    assert((qsg.nsg > 0) != (iov.niov > 0));
+    assert((req->qsg.nsg > 0) != (req->iov.niov > 0));
 
-    if (qsg.nsg > 0) {
+    if (req->qsg.nsg > 0) {
         uint64_t residual;
 
         if (dir == DMA_DIRECTION_TO_DEVICE) {
-            residual = dma_buf_write(ptr, len, &qsg);
+            residual = dma_buf_write(ptr, len, &req->qsg);
         } else {
-            residual = dma_buf_read(ptr, len, &qsg);
+            residual = dma_buf_read(ptr, len, &req->qsg);
         }
 
         if (unlikely(residual)) {
             trace_pci_nvme_err_invalid_dma();
             status = NVME_INVALID_FIELD | NVME_DNR;
         }
-
-        qemu_sglist_destroy(&qsg);
     } else {
         size_t bytes;
 
         if (dir == DMA_DIRECTION_TO_DEVICE) {
-            bytes = qemu_iovec_to_buf(&iov, 0, ptr, len);
+            bytes = qemu_iovec_to_buf(&req->iov, 0, ptr, len);
         } else {
-            bytes = qemu_iovec_from_buf(&iov, 0, ptr, len);
+            bytes = qemu_iovec_from_buf(&req->iov, 0, ptr, len);
         }
 
         if (unlikely(bytes != len)) {
             trace_pci_nvme_err_invalid_dma();
             status = NVME_INVALID_FIELD | NVME_DNR;
         }
-
-        qemu_iovec_destroy(&iov);
     }
 
     return status;
@@ -893,7 +888,7 @@ static uint16_t nvme_smart_info(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
     }
 
     return nvme_dma_prp(n, (uint8_t *) &smart + off, trans_len, prp1, prp2,
-                        DMA_DIRECTION_FROM_DEVICE);
+                        DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_fw_log_info(NvmeCtrl *n, uint32_t buf_len, uint64_t off,
@@ -916,7 +911,7 @@ static uint16_t nvme_fw_log_info(NvmeCtrl *n, uint32_t buf_len, uint64_t off,
     trans_len = MIN(sizeof(fw_log) - off, buf_len);
 
     return nvme_dma_prp(n, (uint8_t *) &fw_log + off, trans_len, prp1, prp2,
-                        DMA_DIRECTION_FROM_DEVICE);
+                        DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_error_info(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
@@ -941,7 +936,7 @@ static uint16_t nvme_error_info(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
     trans_len = MIN(sizeof(errlog) - off, buf_len);
 
     return nvme_dma_prp(n, (uint8_t *)&errlog, trans_len, prp1, prp2,
-                        DMA_DIRECTION_FROM_DEVICE);
+                        DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_get_log(NvmeCtrl *n, NvmeRequest *req)
@@ -1107,7 +1102,7 @@ static uint16_t nvme_identify_ctrl(NvmeCtrl *n, NvmeRequest *req)
     trace_pci_nvme_identify_ctrl();
 
     return nvme_dma_prp(n, (uint8_t *)&n->id_ctrl, sizeof(n->id_ctrl), prp1,
-                        prp2, DMA_DIRECTION_FROM_DEVICE);
+                        prp2, DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_identify_ns(NvmeCtrl *n, NvmeRequest *req)
@@ -1128,7 +1123,7 @@ static uint16_t nvme_identify_ns(NvmeCtrl *n, NvmeRequest *req)
     ns = &n->namespaces[nsid - 1];
 
     return nvme_dma_prp(n, (uint8_t *)&ns->id_ns, sizeof(ns->id_ns), prp1,
-                        prp2, DMA_DIRECTION_FROM_DEVICE);
+                        prp2, DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_identify_nslist(NvmeCtrl *n, NvmeRequest *req)
@@ -1165,7 +1160,7 @@ static uint16_t nvme_identify_nslist(NvmeCtrl *n, NvmeRequest *req)
         }
     }
     ret = nvme_dma_prp(n, (uint8_t *)list, data_len, prp1, prp2,
-                       DMA_DIRECTION_FROM_DEVICE);
+                       DMA_DIRECTION_FROM_DEVICE, req);
     g_free(list);
     return ret;
 }
@@ -1208,7 +1203,7 @@ static uint16_t nvme_identify_ns_descr_list(NvmeCtrl *n, NvmeRequest *req)
     stl_be_p(&ns_descrs->uuid.v, nsid);
 
     return nvme_dma_prp(n, list, NVME_IDENTIFY_DATA_SIZE, prp1, prp2,
-                        DMA_DIRECTION_FROM_DEVICE);
+                        DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_identify(NvmeCtrl *n, NvmeRequest *req)
@@ -1291,7 +1286,7 @@ static uint16_t nvme_get_feature_timestamp(NvmeCtrl *n, NvmeRequest *req)
     uint64_t timestamp = nvme_get_timestamp(n);
 
     return nvme_dma_prp(n, (uint8_t *)&timestamp, sizeof(timestamp), prp1,
-                        prp2, DMA_DIRECTION_FROM_DEVICE);
+                        prp2, DMA_DIRECTION_FROM_DEVICE, req);
 }
 
 static uint16_t nvme_get_feature(NvmeCtrl *n, NvmeRequest *req)
@@ -1425,7 +1420,7 @@ static uint16_t nvme_set_feature_timestamp(NvmeCtrl *n, NvmeRequest *req)
     uint64_t prp2 = le64_to_cpu(cmd->dptr.prp2);
 
     ret = nvme_dma_prp(n, (uint8_t *)&timestamp, sizeof(timestamp), prp1,
-                       prp2, DMA_DIRECTION_TO_DEVICE);
+                       prp2, DMA_DIRECTION_TO_DEVICE, req);
     if (ret != NVME_SUCCESS) {
         return ret;
     }
-- 
2.27.0