On 5/5/22 20:14, isaku.yamahata@xxxxxxxxx wrote:
+/*
+ * Private page can't be release on mmu_notifier without losing page contents.
+ * The help, callback, from backing store is needed to allow page migration.
+ * For now, pin the page.
+ */
+static bool kvm_faultin_pfn_private(struct kvm_vcpu *vcpu,
+ struct kvm_page_fault *fault, int *r)
+{
+ hva_t hva = gfn_to_hva_memslot(fault->slot, fault->gfn);
+ struct page *page[1];
+ unsigned int flags;
+ int npages;
+
+ fault->map_writable = false;
+ fault->pfn = KVM_PFN_ERR_FAULT;
+ *r = -1;
+ if (hva == KVM_HVA_ERR_RO_BAD || hva == KVM_HVA_ERR_BAD)
+ return true;
+
+ /* TDX allows only RWX. Read-only isn't supported. */
+ WARN_ON_ONCE(!fault->write);
+ flags = FOLL_WRITE | FOLL_LONGTERM;
+
+ npages = pin_user_pages_fast(hva, 1, flags, page);
+ if (npages != 1)
+ return true;
+
+ fault->map_writable = true;
+ fault->pfn = page_to_pfn(page[0]);
+ return false;
+}
+
This function is present also in the memfd notifier series. For the
next postings, can you remove all the KVM bits from the series and
include it yourself?
Thanks,
Paolo
