[SeaBIOS] [PATCH] nvme: don't keep probing namespaces after an active one has been found

[Thanos Makatos]

From: Thanos Makatos <tha...@nutanix.com>

The current implementation keeps probing NVMe namespaces even if an
active one has been found. This is unnecessary and most importantly
results in memory allocation failure if the are more than a few dozens
of nmespaces. Also, not probing the remaining namespaces after having
found an active one reduces boot time.

I've tested with 1024 namespaces where 512 where active and it worked
fined.

Signed-off-by: Thanos Makatos <tha...@nutanix.com>
---
 src/hw/nvme.c | 51 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 12 deletions(-)

diff --git a/src/hw/nvme.c b/src/hw/nvme.c
index 746e468..73c1a52 100644
--- a/src/hw/nvme.c
+++ b/src/hw/nvme.c
@@ -233,9 +233,22 @@ nvme_admin_identify_ns(struct nvme_ctrl *ctrl, u32 ns_id)
                                 ns_id)->ns;
 }
 
-static void
+static char*
+nvme_ns_desc(const struct nvme_namespace *ns, u32 ns_id)
+{
+    return znprintf(MAXDESCSIZE, "NVMe NS %u: %llu MiB (%llu %u-byte "
+                                 "blocks + %u-byte metadata)\n",
+                                  ns_id, (ns->lba_count * ns->block_size) >> 
20,
+                                  ns->lba_count, ns->block_size,
+                                  ns->metadata_size);
+}
+
+/* Returns a pointer to the namespace if it's usable, NULL otherwise. */
+struct nvme_namespace*
 nvme_probe_ns(struct nvme_ctrl *ctrl, u32 ns_idx, u8 mdts)
 {
+    struct nvme_namespace *ns = NULL;
+
     u32 ns_id = ns_idx + 1;
 
     struct nvme_identify_ns *id = nvme_admin_identify_ns(ctrl, ns_id);
@@ -257,7 +270,7 @@ nvme_probe_ns(struct nvme_ctrl *ctrl, u32 ns_idx, u8 mdts)
         goto free_buffer;
     }
 
-    struct nvme_namespace *ns = malloc_fseg(sizeof(*ns));
+    ns = malloc_fseg(sizeof(*ns));
     if (!ns) {
         warn_noalloc();
         goto free_buffer;
@@ -277,6 +290,7 @@ nvme_probe_ns(struct nvme_ctrl *ctrl, u32 ns_idx, u8 mdts)
            buffer size. */
         warn_internalerror();
         free(ns);
+        ns = NULL;
         goto free_buffer;
     }
 
@@ -296,16 +310,13 @@ nvme_probe_ns(struct nvme_ctrl *ctrl, u32 ns_idx, u8 mdts)
 
     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,
-                          ns->lba_count, ns->block_size, ns->metadata_size);
-
-    dprintf(3, "%s\n", desc);
-    boot_add_hd(&ns->drive, desc, bootprio_find_pci_device(ctrl->pci));
+    char *desc = nvme_ns_desc(ns, ns_id);
+    dprintf(3, "%s", desc);
+    free(desc);
 
 free_buffer:
     free (id);
+    return ns;
 }
 
 
@@ -560,6 +571,13 @@ nvme_wait_csts_rdy(struct nvme_ctrl *ctrl, unsigned rdy)
     return 0;
 }
 
+static void
+nvme_destroy_io_queues(struct nvme_ctrl *ctrl)
+{
+    nvme_destroy_sq(&ctrl->io_sq);
+    nvme_destroy_cq(&ctrl->io_cq);
+}
+
 /* Returns 0 on success. */
 static int
 nvme_controller_enable(struct nvme_ctrl *ctrl)
@@ -628,15 +646,24 @@ nvme_controller_enable(struct nvme_ctrl *ctrl)
         goto err_destroy_admin_sq;
     }
 
-    /* Populate namespace IDs */
+    /* Find first active namespace. */
     int ns_idx;
-    for (ns_idx = 0; ns_idx < ctrl->ns_count; ns_idx++) {
-        nvme_probe_ns(ctrl, ns_idx, identify->mdts);
+    struct nvme_namespace *ns = NULL;
+    for (ns_idx = 0; ns_idx < ctrl->ns_count && !ns; ns_idx++) {
+        ns = nvme_probe_ns(ctrl, ns_idx, identify->mdts);
+    }
+    if (!ns) {
+        dprintf(3, "no active NVMe namespace\n");
+        goto err_destroy_ioq;
     }
+    boot_add_hd(&ns->drive, nvme_ns_desc(ns, ns_idx + 1),
+                bootprio_find_pci_device(ctrl->pci));
 
     dprintf(3, "NVMe initialization complete!\n");
     return 0;
 
+ err_destroy_ioq:
+    nvme_destroy_io_queues(ctrl);
  err_destroy_admin_sq:
     nvme_destroy_sq(&ctrl->admin_sq);
  err_destroy_admin_cq:
-- 
2.22.3

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