[SeaBIOS] [PATCHv2 6/6] nvme: Only allocate one dma bounce buffer for all nvme drives

[Kevin O'Connor]

There is no need to create multiple dma bounce buffers as the BIOS
disk code isn't reentrant capable.

Also, verify that the allocation succeeds.

Signed-off-by: Kevin O'Connor 
Reviewed-by: Alexander Graf 
---
 src/hw/nvme-int.h |  3 ---
 src/hw/nvme.c     | 21 +++++++++++++++------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/hw/nvme-int.h b/src/hw/nvme-int.h
index f0d717d..f9c807e 100644
--- a/src/hw/nvme-int.h
+++ b/src/hw/nvme-int.h
@@ -117,9 +117,6 @@ struct nvme_namespace {
     u32 block_size;
     u32 metadata_size;
     u32 max_req_size;
-
-    /* Page aligned buffer of size NVME_PAGE_SIZE. */
-    char *dma_buffer;
 };

/* Data structures for NVMe admin identify commands */
diff --git a/src/hw/nvme.c b/src/hw/nvme.c
index e9c449d..3dfa0ce 100644
--- a/src/hw/nvme.c
+++ b/src/hw/nvme.c
@@ -20,6 +20,9 @@
 #include "nvme.h"
 #include "nvme-int.h"

+// Page aligned "dma bounce buffer" of size NVME_PAGE_SIZE in high memory
+static void *nvme_dma_buffer;
+
 static void *
 zalloc_page_aligned(struct zone_s *zone, u32 size)
 {
@@ -257,6 +260,14 @@ nvme_probe_ns(struct nvme_ctrl *ctrl, u32 ns_idx, u8 mdts)
         goto free_buffer;
     }

+    if (!nvme_dma_buffer) {
+        nvme_dma_buffer = zalloc_page_aligned(&ZoneHigh, NVME_PAGE_SIZE);
+        if (!nvme_dma_buffer) {
+            warn_noalloc();
+            goto free_buffer;
+        }
+    }
+
     struct nvme_namespace *ns = malloc_fseg(sizeof(*ns));
     if (!ns) {
         warn_noalloc();
@@ -294,8 +305,6 @@ nvme_probe_ns(struct nvme_ctrl *ctrl, u32 ns_idx, u8 mdts)
         ns->max_req_size = -1U;
     }

-    ns->dma_buffer = zalloc_page_aligned(&ZoneHigh, NVME_PAGE_SIZE);
-
     char *desc = znprintf(MAXDESCSIZE, "NVMe NS %u: %llu MiB (%llu %u-byte "
                           "blocks + %u-byte metadata)",
                           ns_id, (ns->lba_count * ns->block_size) >> 20,
@@ -459,12 +468,12 @@ nvme_bounce_xfer(struct nvme_namespace *ns, u64 lba, void *buf, u16 count,
     u16 blocks = count < max_blocks ? count : max_blocks;

if (write)
-        memcpy(ns->dma_buffer, buf, blocks * ns->block_size);
+        memcpy(nvme_dma_buffer, buf, blocks * ns->block_size);

-    int res = nvme_io_xfer(ns, lba, ns->dma_buffer, NULL, blocks, write);
+    int res = nvme_io_xfer(ns, lba, nvme_dma_buffer, NULL, blocks, write);

if (!write && res >= 0)
-        memcpy(buf, ns->dma_buffer, res * ns->block_size);
+        memcpy(buf, nvme_dma_buffer, res * ns->block_size);

return res;
 }
@@ -498,7 +507,7 @@ nvme_prpl_xfer(struct nvme_namespace *ns, u64 lba, void *buf, u16 count,
     /* Build PRP list if we need to describe more than 2 pages */
     if ((ns->block_size * count) > (NVME_PAGE_SIZE * 2)) {
         u32 prpl_len = 0;
-        u64 *prpl = (void*)ns->dma_buffer;
+        u64 *prpl = nvme_dma_buffer;
         int first_page = 1;
         for (; size > 0; base += NVME_PAGE_SIZE, size -= NVME_PAGE_SIZE) {
             if (first_page) {