CVE-2026-98390

In the Linux kernel, the following vulnerability has been resolved:

x86/amd node: Avoid divide by zero on virtualized systems

On a virtualized system, the number of nodes does not have a relationship to the number of roots. A Xen PVH dom0 can calculate roots per node as 0, which crashes with a divide by zero in:

if (count++ % roots per node)

because the underlying topology code on Xen ends up making num nodes 2 and num roots 1 and the integer division result is 0.

The issue is seen with Xen, but it could affect other systems.

Set roots per node to 1 in this case. Print a firmware bug when this is performed for non-virtualized systems.

[ bp: Massage commit message. ]