On Mon, May 22, 2023 at 04:37:25PM +1000, Alistair Popple wrote: > This problem was discovered during testing of an ARM SMMU > implementation that does not support broadcast TLB maintenance > (BTM). In this case the SMMU driver uses notifiers to issue TLB > invalidates. For read-only to read-write pte upgrades the SMMU > continually returned a read-only PTE to the device, even though the > CPU had a read-write PTE installed. > > Sending a mmu notifier event to the SMMU driver fixes the problem by > flushing secondary TLB entries. A new notifier event type is added so > drivers may filter out these invalidations if not required. Note a > driver should never upgrade or install a PTE in response to this mmu > notifier event as it is not synchronised against other PTE operations. I don't see these SMMU driver changes anywhere. I.e. you're adding dead code as far as I can tell.
