[PATCH RFC v3 31/88] KVM: guest_memfd: Set VM_PFNMAP on VMA in PFN mode

[Ackerley Tng via B4 Relay]

From: Ackerley Tng <ackerleytng@xxxxxxxxxx>

In PFN mode, guest_memfd memory is backed by raw PFNs rather than
page-cache folios.

Mark the VMA with VM_PFNMAP when setting up the VMA in PFN mode so that
the core memory management subsystem recognizes the mapping as PFN-backed.

Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
 virt/kvm/guest_memfd.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 180418c65a1ae..183e15775523f 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -652,6 +652,8 @@ static const struct vm_operations_struct kvm_gmem_vm_ops = {
 
 static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma)
 {
+	struct gmem_inode *gi = GMEM_I(file_inode(file));
+
 	if (!kvm_gmem_supports_mmap(file_inode(file)))
 		return -ENODEV;
 
@@ -660,6 +662,9 @@ static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma)
 		return -EINVAL;
 	}
 
+	if (kvm_gmem_is_pfn_mode(gi))
+		vm_flags_set(vma, VM_PFNMAP);
+
 	vma->vm_ops = &kvm_gmem_vm_ops;
 
 	return 0;

-- 
2.56.0.455.g6c5a503b38-goog