On Mon, Jan 23, 2023 at 11:07:25PM +0000, Oliver Upton wrote: > On Tue, Jan 10, 2023 at 02:24:29AM +0000, Ricardo Koller wrote: > > Only Stage1 Page table walks (S1PTW) writing a PTE on an unmapped page > > should result in a userfaultfd write. However, the userfaultfd tests in > > page_fault_test wrongly assert that any S1PTW is a PTE write. > > > > Fix this by relaxing the read vs. write checks in all userfaultfd handlers. > > Note that this is also an attempt to focus less on KVM (and userfaultfd) > > behavior, and more on architectural behavior. Also note that after commit > > "KVM: arm64: Fix S1PTW handling on RO memslots" the userfaultfd fault > > (S1PTW with AF on an unmaped PTE page) is actually a read: the translation > > fault that comes before the permission fault. > > I certainly agree that we cannot make assertions about read v. write > when registering uffd in 'missing' mode. We probably need another test > to assert that we get write faults for hardware AF updates when using > uffd in write protect mode. I can do that. Only question, do you prefer having them in this series with fixes, or another one? > > -- > Thanks, > Oliver
