The "Memory Proximity Domain Attributes" structure of the ACPI HMAT
has a "Processor Proximity Domain Valid" flag that is currently
always set because Qemu -numa requires an initiator=X value
when hmat=on. Unsetting this flag allows to create more complex
memory topologies by having multiple best initiators for a single
memory target.

This patch allows -numa without initiator=X when hmat=on by keeping
the default value MAX_NODES in numa_state->nodes[i].initiator.
All places reading numa_state->nodes[i].initiator already check
whether it's different from MAX_NODES before using it.

Tested with
qemu-system-x86_64 -accel kvm \
 -machine pc,hmat=on \
 -drive if=pflash,format=raw,file=./OVMF.fd \
 -drive media=disk,format=qcow2,file=efi.qcow2 \
 -smp 4 \
 -m 3G \
 -object memory-backend-ram,size=1G,id=ram0 \
 -object memory-backend-ram,size=1G,id=ram1 \
 -object memory-backend-ram,size=1G,id=ram2 \
 -numa node,nodeid=0,memdev=ram0,cpus=0-1 \
 -numa node,nodeid=1,memdev=ram1,cpus=2-3 \
 -numa node,nodeid=2,memdev=ram2 \
 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-latency,latency=10 \
 -numa hmat-lb,initiator=0,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=10485760 \
 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-latency,latency=20 \
 -numa hmat-lb,initiator=0,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=5242880 \
 -numa hmat-lb,initiator=0,target=2,hierarchy=memory,data-type=access-latency,latency=30 \
 -numa hmat-lb,initiator=0,target=2,hierarchy=memory,data-type=access-bandwidth,bandwidth=1048576 \
 -numa hmat-lb,initiator=1,target=0,hierarchy=memory,data-type=access-latency,latency=20 \
 -numa hmat-lb,initiator=1,target=0,hierarchy=memory,data-type=access-bandwidth,bandwidth=5242880 \
 -numa hmat-lb,initiator=1,target=1,hierarchy=memory,data-type=access-latency,latency=10 \
 -numa hmat-lb,initiator=1,target=1,hierarchy=memory,data-type=access-bandwidth,bandwidth=10485760 \
 -numa hmat-lb,initiator=1,target=2,hierarchy=memory,data-type=access-latency,latency=30 \
 -numa hmat-lb,initiator=1,target=2,hierarchy=memory,data-type=access-bandwidth,bandwidth=1048576
which reports NUMA node2 at same distance from both node0 and node1 as seen in lstopo:
Machine (2966MB total) + Package P#0
  NUMANode P#2 (979MB)
  Group0
    NUMANode P#0 (980MB)
    Core P#0 + PU P#0
    Core P#1 + PU P#1
  Group0
    NUMANode P#1 (1007MB)
    Core P#2 + PU P#2
    Core P#3 + PU P#3

Before this patch, we had to add ",initiator=X" to "-numa node,nodeid=2,memdev=ram2".
The lstopo output difference between initiator=1 and no initiator is:
@@ -1,10 +1,10 @@
 Machine (2966MB total) + Package P#0
+  NUMANode P#2 (979MB)
   Group0
     NUMANode P#0 (980MB)
     Core P#0 + PU P#0
     Core P#1 + PU P#1
   Group0
     NUMANode P#1 (1007MB)
-    NUMANode P#2 (979MB)
     Core P#2 + PU P#2
     Core P#3 + PU P#3

Corresponding changes in the HMAT MPDA structure:
@@ -49,10 +49,10 @@
 [078h 0120   2]               Structure Type : 0000 [Memory Proximity Domain Attributes]
 [07Ah 0122   2]                     Reserved : 0000
 [07Ch 0124   4]                       Length : 00000028
-[080h 0128   2]        Flags (decoded below) : 0001
-            Processor Proximity Domain Valid : 1
+[080h 0128   2]        Flags (decoded below) : 0000
+            Processor Proximity Domain Valid : 0
 [082h 0130   2]                    Reserved1 : 0000
-[084h 0132   4] Attached Initiator Proximity Domain : 00000001
+[084h 0132   4] Attached Initiator Proximity Domain : 00000080
 [088h 0136   4]      Memory Proximity Domain : 00000002
 [08Ch 0140   4]                    Reserved2 : 00000000
 [090h 0144   8]                    Reserved3 : 0000000000000000

Final HMAT SLLB structures:
[0A0h 0160   2]               Structure Type : 0001 [System Locality Latency and Bandwidth Information]
[0A2h 0162   2]                     Reserved : 0000
[0A4h 0164   4]                       Length : 00000040
[0A8h 0168   1]        Flags (decoded below) : 00
                            Memory Hierarchy : 0
[0A9h 0169   1]                    Data Type : 00
[0AAh 0170   2]                    Reserved1 : 0000
[0ACh 0172   4] Initiator Proximity Domains # : 00000002
[0B0h 0176   4]   Target Proximity Domains # : 00000003
[0B4h 0180   4]                    Reserved2 : 00000000
[0B8h 0184   8]              Entry Base Unit : 0000000000002710
[0C0h 0192   4] Initiator Proximity Domain List : 00000000
[0C4h 0196   4] Initiator Proximity Domain List : 00000001
[0C8h 0200   4] Target Proximity Domain List : 00000000
[0CCh 0204   4] Target Proximity Domain List : 00000001
[0D0h 0208   4] Target Proximity Domain List : 00000002
[0D4h 0212   2]                        Entry : 0001
[0D6h 0214   2]                        Entry : 0002
[0D8h 0216   2]                        Entry : 0003
[0DAh 0218   2]                        Entry : 0002
[0DCh 0220   2]                        Entry : 0001
[0DEh 0222   2]                        Entry : 0003

[0E0h 0224   2]               Structure Type : 0001 [System Locality Latency and Bandwidth Information]
[0E2h 0226   2]                     Reserved : 0000
[0E4h 0228   4]                       Length : 00000040
[0E8h 0232   1]        Flags (decoded below) : 00
                            Memory Hierarchy : 0
[0E9h 0233   1]                    Data Type : 03
[0EAh 0234   2]                    Reserved1 : 0000
[0ECh 0236   4] Initiator Proximity Domains # : 00000002
[0F0h 0240   4]   Target Proximity Domains # : 00000003
[0F4h 0244   4]                    Reserved2 : 00000000
[0F8h 0248   8]              Entry Base Unit : 0000000000000001
[100h 0256   4] Initiator Proximity Domain List : 00000000
[104h 0260   4] Initiator Proximity Domain List : 00000001
[108h 0264   4] Target Proximity Domain List : 00000000
[10Ch 0268   4] Target Proximity Domain List : 00000001
[110h 0272   4] Target Proximity Domain List : 00000002
[114h 0276   2]                        Entry : 000A
[116h 0278   2]                        Entry : 0005
[118h 0280   2]                        Entry : 0001
[11Ah 0282   2]                        Entry : 0005
[11Ch 0284   2]                        Entry : 000A
[11Eh 0286   2]                        Entry : 0001

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: Hesham Almatary <hesham.almatary@huawei.com>
Reviewed-by: Jingqi Liu <jingqi.liu@intel.com>
Message-Id: <20221027100037.251-2-hesham.almatary@huawei.com>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>