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 kalyazin@amazon.com
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 <linux/kvm_host.h> #include <linux/pagemap.h> #include <linux/anon_inodes.h> +#ifdef CONFIG_KVM_PRIVATE_MEM +#include <linux/userfaultfd_k.h> +#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