KVM: arm64: nv: fix VNCR TLB ASID match logic for non-Global entries
kvm_vncr_tlb_lookup() is supposed to return true when the cached VNCR
TLB entry is valid for the current context. For non-Global entries, that
means the entry’s ASID must match the current ASID.
The current code returns true when the ASIDs do *not* match, which
inverts the logic. This is a potential vulnerability:
- Valid entries are ignored and we fall back to kvm_translate_vncr(),
hurting performance.
- Mismatched entries are treated as permission faults (-EPERM) instead
of triggering a fresh translation.
- This can also cause stale translations to be (wrongly) considered
valid across address spaces.
Flip the predicate so non-Global entries only hit when ASIDs match.
Special credit to Team 0xB6 for reporting: DongHa Lee, Gyujeong Jin,
Daehyeon Ko, Geonha Lee, Hyungyu Oh, and Jaewon Yang.
Signed-off-by: Geonha Lee <w1nsom3gna@korea.ac.kr>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250903150421.90752-1-w1nsom3gna@korea.ac.kr
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>