hmat acpi: Do not add Memory Proximity Domain Attributes Structure targetting non...

If qemu is started with a proximity node containing CPUs alone,
it will provide one of these structures to say memory in this
node is directly connected to itself.

This description is arguably pointless even if there is memory
in the node.  If there is no memory present, and hence no SRAT
entry it breaks Linux HMAT passing and the table is rejected.

https://elixir.bootlin.com/linux/v6.7/source/drivers/acpi/numa/hmat.c#L444

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20240307160326.31570-2-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/acpi/hmat.c b/hw/acpi/hmat.c
index 2242981e1809e3e3e3307611b4ed8b20ca654f88..8ea240878aec4679a9bfdace29d8ea661316efef 100644 (file)
--- a/hw/acpi/hmat.c
+++ b/hw/acpi/hmat.c
@@ -204,6 +204,13 @@ static void hmat_build_table_structs(GArray *table_data, NumaState *numa_state)
     build_append_int_noprefix(table_data, 0, 4); /* Reserved */
 
     for (i = 0; i < numa_state->num_nodes; i++) {
+        /*
+         * Linux rejects whole HMAT table if a node with no memory
+         * has one of these structures listing it as a target.
+         */
+        if (!numa_state->nodes[i].node_mem) {
+            continue;
+        }
         flags = 0;
 
         if (numa_state->nodes[i].initiator < MAX_NODES) {