Marc, On Thu, Mar 16, 2023 at 05:45:45PM +0000, Marc Zyngier wrote: > We walk the userspace PTs to discover what mapping size was > used there. However, this can race against the userspace tables > being freed, and we end-up in the weeds. > > Thankfully, the mm code is being generous and will IPI us when > doing so. So let's implement our part of the bargain and disable > interrupts around the walk. This ensures that nothing terrible > happens during that time. > > We still need to handle the removal of the page tables before > the walk. For that, allow get_user_mapping_size() to return an > error, and make sure this error can be propagated all the way > to the the exit handler. > > Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx Looks good. I've squashed in this meaningless diff to make use of an existing helper. diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index e95593736ae3..3b9d4d24c361 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -691,7 +691,7 @@ static int get_user_mapping_size(struct kvm *kvm, u64 addr) return -EFAULT; /* Oops, the userspace PTs are gone... Replay the fault */ - if (!(pte & PTE_VALID)) + if (!kvm_pte_valid(pte)) return -EAGAIN; return BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level)); -- Thanks, Oliver
