KVM: guest_memfd: extract __kvm_gmem_get_pfn()

In preparation for adding a function that walks a set of pages
provided by userspace and populates them in a guest_memfd,
add a version of kvm_gmem_get_pfn() that has a "bool prepare"
argument and passes it down to kvm_gmem_get_folio().

Populating guest memory has to call repeatedly __kvm_gmem_get_pfn()
on the same file, so make the new function take struct file*.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 0176089be7314eb733952089e0c746199f18a944..bfe437098b79943a73bd4bfa4c862fbbf2c64191 100644 (file)
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -528,33 +528,29 @@ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
        fput(file);
 }
 
-int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
-                    gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
+static int __kvm_gmem_get_pfn(struct file *file, struct kvm_memory_slot *slot,
+                      gfn_t gfn, kvm_pfn_t *pfn, int *max_order, bool prepare)
 {
        pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
-       struct kvm_gmem *gmem;
+       struct kvm_gmem *gmem = file->private_data;
        struct folio *folio;
        struct page *page;
-       struct file *file;
        int r;
 
-       file = kvm_gmem_get_file(slot);
-       if (!file)
+       if (file != slot->gmem.file) {
+               WARN_ON_ONCE(slot->gmem.file);
                return -EFAULT;
+       }
 
        gmem = file->private_data;
-
        if (xa_load(&gmem->bindings, index) != slot) {
                WARN_ON_ONCE(xa_load(&gmem->bindings, index));
-               r = -EIO;
-               goto out_fput;
+               return -EIO;
        }
 
-       folio = kvm_gmem_get_folio(file_inode(file), index, true);
-       if (IS_ERR(folio)) {
-               r = PTR_ERR(folio);
-               goto out_fput;
-       }
+       folio = kvm_gmem_get_folio(file_inode(file), index, prepare);
+       if (IS_ERR(folio))
+               return PTR_ERR(folio);
 
        if (folio_test_hwpoison(folio)) {
                r = -EHWPOISON;
@@ -571,9 +567,21 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
 
 out_unlock:
        folio_unlock(folio);
-out_fput:
-       fput(file);
 
        return r;
 }
+
+int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
+                    gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
+{
+       struct file *file = kvm_gmem_get_file(slot);
+       int r;
+
+       if (!file)
+               return -EFAULT;
+
+       r = __kvm_gmem_get_pfn(file, slot, gfn, pfn, max_order, true);
+       fput(file);
+       return r;
+}
 EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn);