[PATCH] PCI: hv: Set default NUMA node to 0 for devices without affinity info

[Long Li <longli@microsoft.com>]

When a Hyper-V PCI device does not have
HV_PCI_DEVICE_FLAG_NUMA_AFFINITY set or has an out-of-range
virtual_numa_node, hv_pci_assign_numa_node() leaves the device
NUMA node unset. On x86_64, the default NUMA node happens to be
0, but on ARM64 it is NUMA_NO_NODE (-1), leading to inconsistent
behavior across architectures.

In Azure, when no NUMA information is available from the host,
devices perform best when assigned to node 0. Set the device NUMA
node to 0 unconditionally before the conditional NUMA affinity
check, so that devices always get a valid default and behavior is
consistent on both x86_64 and ARM64.

Fixes: 999dd956d838 ("PCI: hv: Add support for protocol 1.3 and support PCI_BUS_RELATIONS2")
Signed-off-by: Long Li <longli@microsoft.com>
---
 drivers/pci/controller/pci-hyperv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 2c7a406b4ba8..5c03b6e4cdab 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -2485,6 +2485,9 @@ static void hv_pci_assign_numa_node(struct hv_pcibus_device *hbus)
 		if (!hv_dev)
 			continue;
 
+		/* Default to node 0 for consistent behavior across architectures */
+		set_dev_node(&dev->dev, 0);
+
 		if (hv_dev->desc.flags & HV_PCI_DEVICE_FLAG_NUMA_AFFINITY &&
 		    hv_dev->desc.virtual_numa_node < num_possible_nodes())
 			/*
-- 
2.43.0