On 2023-03-16 23:42, Oliver Upton wrote:
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;
Sure, LGTM.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
