CVE-2026-98639

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

KVM: riscv: Fix NACL hfence entry update order

The SBI v3.0 specification (section 15.1.2) requires a nested HFENCE entry to be populated as follows:

kvm riscv nacl hfence() writes the Config word first, so the SBI implementation (or NACL hardware) can observe a pending entry with pnum/pcount values left over from the previous use of that entry, resulting in incorrect TLB flush ranges.

Write pnum and pcount first and the Config word last. Since the consumer is an external agent on coherent shared memory, use WRITE ONCE() to stop the compiler from reordering the stores and smp wmb() to make the parameter words globally visible before the Pending bit is set.