On 02/04/2025 22:25, James Houghton wrote:
On Wed, Apr 2, 2025 at 9:08 AM Nikita Kalyazin <kalya...@amazon.com> wrote:Signed-off-by: Nikita Kalyazin <kalya...@amazon.com> --- 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) +#endifMaybe a better way to do this is to add a vm_ops->can_userfault() or something, so we could write something like this: if (vma->vm_ops && !vma->vm_ops->can_userfault) return false; if (vma->vm_ops && !vma->vm_ops->can_userfault(vm_flags)) return false;
I like that, thanks! What do you see passing vm_flags being useful for? Shall we pass the entire vma struct like in most of other callbacks?
And shmem/hugetlbfs can advertise support for everything they already support that way.+ ) 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
