diff mbox series

[v2,2/2] hw/arm/virt: Don't create device-tree node for empty NUMA node

Message ID 20211012063603.166255-3-gshan@redhat.com (mailing list archive)
State New, archived
Headers show
Series hw/arm/virt: Fix qemu booting failure on device-tree | expand

Commit Message

Gavin Shan Oct. 12, 2021, 6:36 a.m. UTC
The empty NUMA node, where no memory resides, are allowed. For
example, the following command line specifies two empty NUMA nodes.
With this, QEMU fails to boot because of the conflicting device-tree
node names, as the following error message indicates.

  /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \
  -accel kvm -machine virt,gic-version=host               \
  -cpu host -smp 4,sockets=2,cores=2,threads=1            \
  -m 1024M,slots=16,maxmem=64G                            \
  -object memory-backend-ram,id=mem0,size=512M            \
  -object memory-backend-ram,id=mem1,size=512M            \
  -numa node,nodeid=0,cpus=0-1,memdev=mem0                \
  -numa node,nodeid=1,cpus=2-3,memdev=mem1                \
  -numa node,nodeid=2                                     \
  -numa node,nodeid=3
    :
  qemu-system-aarch64: FDT: Failed to create subnode /memory@80000000: FDT_ERR_EXISTS

As specified by linux device-tree binding document, the device-tree
nodes for these empty NUMA nodes shouldn't be generated. However,
the corresponding NUMA node IDs should be included in the distance
map device-tree node. This skips populating the device-tree nodes
for these empty NUMA nodes to avoid the error, so that QEMU can be
started successfully.

Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
---
 hw/arm/boot.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 57efb61ee4..4e5898fcdc 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -603,6 +603,10 @@  int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
         mem_base = binfo->loader_start;
         for (i = 0; i < ms->numa_state->num_nodes; i++) {
             mem_len = ms->numa_state->nodes[i].node_mem;
+            if (!mem_len) {
+                continue;
+            }
+
             rc = fdt_add_memory_node(fdt, acells, mem_base,
                                      scells, mem_len, i);
             if (rc < 0) {