[PATCH v2 3/5] mm: userfaultfd: allow to register continue for guest_memfd

From: Nikita Kalyazin
Date: Wed Apr 02 2025 - 12:10:49 EST


Signed-off-by: Nikita Kalyazin <kalyazin@xxxxxxxxxx>
---
include/linux/userfaultfd_k.h | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 75342022d144..bc184edfbb85 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -212,6 +212,10 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
return vma->vm_flags & __VM_UFFD_FLAGS;
}

+#ifdef CONFIG_KVM_PRIVATE_MEM
+bool kvm_gmem_vma_is_gmem(struct vm_area_struct *vma);
+#endif
+
static inline bool vma_can_userfault(struct vm_area_struct *vma,
unsigned long vm_flags,
bool wp_async)
@@ -222,7 +226,11 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma,
return false;

if ((vm_flags & VM_UFFD_MINOR) &&
- (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
+ (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma))
+#ifdef CONFIG_KVM_PRIVATE_MEM
+ && !kvm_gmem_vma_is_gmem(vma)
+#endif
+ )
return false;

/*
@@ -244,6 +252,9 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma,

/* By default, allow any of anon|shmem|hugetlb */
return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
+#ifdef CONFIG_KVM_PRIVATE_MEM
+ kvm_gmem_vma_is_gmem(vma) ||
+#endif
vma_is_shmem(vma);
}

--
2.47.1