CVE-2026-72278: KVM: arm64: nv: Re-translate VNCR before injecting abort

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

KVM: arm64: nv: Re-translate VNCR before injecting abort

KVM faults in the VNCR page with FOLLWRITE whenever the guest aborts for a write, similar to how a regular stage-2 mapping is handled. It is entirely possible that the guest reads from the VNCR before writing to it, in which case the PFN could only be read-only.

Invalidate the VNCR TLB and re-fetch the translation upon taking a VNCR abort, allowing the host mapping to be faulted in for write the second time around. Interestingly enough, this also satisfies the ordering requirements of FEATETS2/3 between descriptor updates and MMU faults.