Merge tag 'vfio-v6.15-rc6' of https://github.com/awilliam/linux-vfio

Pull vfio fix from Alex Williamson:

 - Fix an issue in vfio-pci huge_fault handling by aligning faults to
   the order, resulting in deterministic use of huge pages.  This
   avoids a race where simultaneous aligned and unaligned faults to
   the same PMD can result in a VM_FAULT_OOM and subsequent VM crash.
   (Alex Williamson)

* tag 'vfio-v6.15-rc6' of https://github.com/awilliam/linux-vfio:
  vfio/pci: Align huge faults to order

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 35f9046af315..6328c3a05bcd 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/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;
 	}