Re: [PATCH RFC] hw/cxl: type 3 devices can now present volatile or persistent memory

[Davidlohr Bueso <dave@stgolabs.net>]

On Thu, 06 Oct 2022, Jonathan Cameron wrote:

>One of the blockers for volatile support was that we had no means to poke
>it properly as the kernel doesn't yet support volatile capacity and
>no one has done the relevant work in EDK2 or similar to do it before the kernel boots.
>There has been some work on EDK2 support for ARM N2 FVPs from
>Saanta Pattanayak, but not upstream eyt.
>https://lpc.events/event/16/contributions/1254/

fwiw I had been trying to build some of the firmware bootup for the required
acpi tables that are particular to volatile capacity steps (srat/slit, hmat and
EFI Memory Map) by parameters, but got quickly out of hand. For example, the srat
could use a passed 'node' and have a cxl_build_srat(), etc. But yeah it would
be nice for the EDK2 work to advance on the x86 end.

Thanks,
Davidlohr

diff --git a/hw/acpi/cxl.c b/hw/acpi/cxl.c
index 2bf8c0799359..1c3c6d17c222 100644
--- a/hw/acpi/cxl.c
+++ b/hw/acpi/cxl.c
@@ -254,3 +255,46 @@ void build_cxl_osc_method(Aml *dev)
+static int cxl_device_list(Object *obj, void *opaque)
+{
+    GSList **list = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_CXL_TYPE3)) {
+        *list = g_slist_append(*list, DEVICE(obj));
+    }
+
+    object_child_foreach(obj, cxl_device_list, opaque);
+    return 0;
+}
+
+static GSList *cxl_get_device_list(void)
+{
+    GSList *list = NULL;
+
+    object_child_foreach(qdev_get_machine(), cxl_device_list, &list);
+    return list;
+}
+
+void cxl_build_srat(GArray *table_data)
+{
+    GSList *device_list, *list = cxl_get_device_list();
+
+    for (device_list = list; device_list; device_list = device_list->next) {
+        DeviceState *dev = device_list->data;
+        Object *obj = OBJECT(dev);
+        CXLType3Dev *ct3d = CXL_TYPE3(dev);
+        MemoryRegion *mr;
+        int node;
+
+        mr = host_memory_backend_get_memory(ct3d->hostmem);
+        if (!mr) {
+            continue;
+        }
+        node = object_property_get_uint(obj, "node", &error_abort);
+
+        build_srat_memory(table_data, mr->addr, mr->size, node, MEM_AFFINITY_ENABLED);
+    }
+
+    g_slist_free(list);
+}