RE: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory
From: Wang, Wei W <hidden>
Date: 2023-07-25 15:09:43
Also in:
kvm, kvm-riscv, kvmarm, linux-fsdevel, linux-mips, linux-mm, linux-riscv, linuxppc-dev, lkml
On Wednesday, July 19, 2023 7:45 AM, Sean Christopherson wrote:
+int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
+ gfn_t gfn, kvm_pfn_t *pfn, int *max_order) {
+ pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
+ struct kvm_gmem *gmem;
+ struct folio *folio;
+ struct page *page;
+ struct file *file;
+
+ file = kvm_gmem_get_file(slot);
+ if (!file)
+ return -EFAULT;
+
+ gmem = file->private_data;
+
+ if (WARN_ON_ONCE(xa_load(&gmem->bindings, index) != slot)) {
+ fput(file);
+ return -EIO;
+ }
+
+ folio = kvm_gmem_get_folio(file_inode(file), index);
+ if (!folio) {
+ fput(file);
+ return -ENOMEM;
+ }
+
+ page = folio_file_page(folio, index);
+
+ *pfn = page_to_pfn(page);
+ *max_order = compound_order(compound_head(page));Maybe better to check if caller provided a buffer to get the max_order: if (max_order) *max_order = compound_order(compound_head(page)); This is what the previous version did (restrictedmem_get_page), so that callers who only want to get a pfn don't need to define an unused "order" param.