From: Michal Privoznik <mprivozn@redhat.com>

A memory device can have <nodemask/> which specifies which host
NUMA nodes the memory should be allocated from (currently
supported for dimm, virtio-mem and sgx-epc models).
But when generating corresponding command line for the device,
the NUMA policy is taken from the guest NUMA node that
corresponds to the memory device (as defined by target/node) or
overall domain NUMA policy (as defined by <numatune/>).

This may lead to memory being allocated from unexpected NUMA
node. For instance, if the memory device has
<nodemask>0</nodemask> and domain has <numatune> <memory
mode='preferred' nodeset='1'/> </numatune> then the cmd line for
the memory device also has just "policy":"preferred".

Treat <nodemask/> as mode='strict'.

But I agree that this is kind of nonsense configuration. Why
would somebody want to prefer one NUMA node but then configure
memory device to allocate NUMA from the other?

Resolves: https://issues.redhat.com/browse/RHEL-114415
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_command.c                                     | 6 ++++++
 .../memory-hotplug-numa-preferred.x86_64-latest.args        | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index b69fe23236..3736c1bafc 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -3497,6 +3497,12 @@ qemuBuildMemoryBackendProps(virJSONValue **backendProps,
         if (!virNumaNodesetIsAvailable(nodemask))
             return -1;
 
+        /* Treat source nodes as strict mode, regardless of the target guest
+         * NUMA node mode. */
+        if (hasSourceNodes) {
+            mode = VIR_DOMAIN_NUMATUNE_MEM_STRICT;
+        }
+
         /* If mode is "restrictive", we should only use cgroups setting allowed memory
          * nodes, and skip passing the host-nodes and policy parameters to QEMU command
          * line which means we will use system default memory policy. */
diff --git a/tests/qemuxmlconfdata/memory-hotplug-numa-preferred.x86_64-latest.args b/tests/qemuxmlconfdata/memory-hotplug-numa-preferred.x86_64-latest.args
index 23a5f76af2..cc318977b3 100644
--- a/tests/qemuxmlconfdata/memory-hotplug-numa-preferred.x86_64-latest.args
+++ b/tests/qemuxmlconfdata/memory-hotplug-numa-preferred.x86_64-latest.args
@@ -34,7 +34,7 @@ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
 -device '{"driver":"pcie-root-port","port":10,"chassis":3,"id":"pci.3","bus":"pcie.0","addr":"0x1.0x2"}' \
 -device '{"driver":"qemu-xhci","id":"usb","bus":"pci.1","addr":"0x0"}' \
 -object '{"qom-type":"thread-context","id":"tc-memdimm0","node-affinity":[0]}' \
--object '{"qom-type":"memory-backend-file","id":"memdimm0","mem-path":"/dev/hugepages1G/libvirt/qemu/-1-QEMUGuest1","prealloc":true,"size":1073741824,"host-nodes":[0],"policy":"preferred","prealloc-context":"tc-memdimm0"}' \
+-object '{"qom-type":"memory-backend-file","id":"memdimm0","mem-path":"/dev/hugepages1G/libvirt/qemu/-1-QEMUGuest1","prealloc":true,"size":1073741824,"host-nodes":[0],"policy":"bind","prealloc-context":"tc-memdimm0"}' \
 -device '{"driver":"pc-dimm","node":0,"memdev":"memdimm0","id":"dimm0","slot":0}' \
 -audiodev '{"id":"audio1","driver":"none"}' \
 -global ICH9-LPC.noreboot=off \
-- 
2.51.2