Sean Christopherson wrote: > Use atomic64_dec_return() when decrementing the number of "pre-mapped" > S-EPT pages to ensure that the count can't go negative without KVM > noticing. In theory, checking for '0' and then decrementing in a separate > operation could miss a 0=>-1 transition. In practice, such a condition is > impossible because nr_premapped is protected by slots_lock, i.e. doesn't > actually need to be an atomic (that wart will be addressed shortly). > > Don't bother trying to keep the count non-negative, as the KVM_BUG_ON() > ensures the VM is dead, i.e. there's no point in trying to limp along. > > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Reviewed-by: Ira Weiny <ira.weiny@xxxxxxxxx> [snip]
