Ackerley Tng <[email protected]> writes: > All-shared guest_memfd used to be only supported for non-CoCo VMs where > preparation doesn't apply. INIT_SHARED is about to be supported for > non-CoCo VMs in a later patch in this series. > > In addition, KVM_SET_MEMORY_ATTRIBUTES2 is about to be supported in > guest_memfd in a later patch in this series. > > This means that the kvm fault handler may now call kvm_gmem_get_pfn() on a > shared folio for a CoCo VM where preparation applies. > > Add a check to make sure that preparation is only performed for private > folios. > > Preparation will be undone on freeing (see kvm_gmem_free_folio()) and on > conversion to shared. > > Signed-off-by: Ackerley Tng <[email protected]> > --- > virt/kvm/guest_memfd.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index b6ffa8734175d..d414ebfcb4c19 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -900,6 +900,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct > kvm_memory_slot *slot, > int *max_order) > { > pgoff_t index = kvm_gmem_get_index(slot, gfn); > + struct inode *inode; > struct folio *folio; > int r = 0; > > @@ -907,7 +908,8 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct > kvm_memory_slot *slot, > if (!file) > return -EFAULT; > > - filemap_invalidate_lock_shared(file_inode(file)->i_mapping); > + inode = file_inode(file); > + filemap_invalidate_lock_shared(inode->i_mapping); > > folio = __kvm_gmem_get_pfn(file, slot, index, pfn, max_order); > if (IS_ERR(folio)) { > @@ -920,7 +922,8 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct > kvm_memory_slot *slot, > folio_mark_uptodate(folio); > } > > - r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio); > + if (kvm_gmem_is_private_mem(inode, index)) > + r = kvm_gmem_prepare_folio(kvm, slot, gfn, folio);
Michael, I might have misunderstood you at the last guest_memfd call: sev_gmem_prepare() doesn't prepare a page for being a shared page, right? Does this work? That prepare is only called to "make private"? > > folio_unlock(folio); > > @@ -930,7 +933,7 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct > kvm_memory_slot *slot, > folio_put(folio); > > out: > - filemap_invalidate_unlock_shared(file_inode(file)->i_mapping); > + filemap_invalidate_unlock_shared(inode->i_mapping); > return r; > } > EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_get_pfn); > > -- > 2.53.0.1018.g2bb0e51243-goog
