Merge: vfio/pci: Align huge faults to order

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/882

JIRA: https://issues.redhat.com/browse/RHEL-89852

Upstream Status: mainline

Testing: GPU and NIC (PF & VF) VM assignment, unit testing

Obligatory comment

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Approved-by: Peter Xu <peterx@redhat.com>
Approved-by: Donald Dutile <ddutile@redhat.com>
Approved-by: Cédric Le Goater <clg@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>

Author: CKI KWF Bot

drivers/vfio/pci/vfio_pci_core.c

@@ -1646,14 +1646,14 @@ static vm_fault_t vfio_pci_mmap_huge_fault(struct vm_fault *vmf,
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct vfio_pci_core_device *vdev = vma->vm_private_data;
-	unsigned long pfn, pgoff = vmf->pgoff - vma->vm_pgoff;
+	unsigned long addr = vmf->address & ~((PAGE_SIZE << order) - 1);
+	unsigned long pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
+	unsigned long pfn = vma_to_pfn(vma) + pgoff;
 	vm_fault_t ret = VM_FAULT_SIGBUS;
 
-	pfn = vma_to_pfn(vma) + pgoff;
-
-	if (order && (pfn & ((1 << order) - 1) ||
-		      vmf->address & ((PAGE_SIZE << order) - 1) ||
-		      vmf->address + (PAGE_SIZE << order) > vma->vm_end)) {
+	if (order && (addr < vma->vm_start ||
+		      addr + (PAGE_SIZE << order) > vma->vm_end ||
+		      pfn & ((1 << order) - 1))) {
 		ret = VM_FAULT_FALLBACK;
 		goto out;
 	}