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charset=utf-8 Content-Disposition: inline In-Reply-To: <20250404154352.23078-5-kalyazin@amazon.com> On Fri, Apr 04, 2025 at 03:43:50PM +0000, Nikita Kalyazin wrote: > Add support for sending a pagefault event if userfaultfd is registered. > Only page minor event is currently supported. > > Signed-off-by: Nikita Kalyazin > --- > virt/kvm/guest_memfd.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index fbf89e643add..096d89e7282d 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -4,6 +4,9 @@ > #include > #include > #include > +#ifdef CONFIG_KVM_PRIVATE_MEM > +#include > +#endif /* CONFIG_KVM_PRIVATE_MEM */ > > #include "kvm_mm.h" > > @@ -380,6 +383,13 @@ static vm_fault_t kvm_gmem_fault(struct vm_fault *vmf) > kvm_gmem_mark_prepared(folio); > } > > + if (userfaultfd_minor(vmf->vma) && > + !(vmf->flags & FAULT_FLAG_USERFAULT_CONTINUE)) { > + folio_unlock(folio); > + filemap_invalidate_unlock_shared(inode->i_mapping); > + return handle_userfault(vmf, VM_UFFD_MINOR); > + } > + Hmm, does guest-memfd (when with your current approach) at least needs to define the new can_userfault() hook? Meanwhile, we have some hard-coded lines so far, like: mfill_atomic(): if (!vma_is_shmem(dst_vma) && uffd_flags_mode_is(flags, MFILL_ATOMIC_CONTINUE)) goto out_unlock; I thought it would fail guest-memfd already on a CONTINUE request, and it doesn't seem to be touched yet in this series. I'm not yet sure how the test worked out without hitting things like it. Highly likely I missed something. Some explanations would be welcomed.. Thanks, > vmf->page = folio_file_page(folio, vmf->pgoff); > > out_folio: > -- > 2.47.1 > -- Peter Xu