[PATCH 1/3] vfio/pci: Set VFIO_PCI_OFFSET_SHIFT to 48

Julian Ruess
2026-02-12T14:02:46Z

Extend VFIO_PCI_OFFSET_SHIFT to 48 to use the vfio-pci
VFIO_PCI_OFFSET_TO_INDEX() mechanism with the 256 TiB pseudo-BAR 0 of
the ISM device on s390. This bar is never mapped.

Acked-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Julian Ruess <julianr@linux.ibm.com>
---
drivers/vfio/pci/vfio_pci_core.c | 4 ++--
include/linux/vfio_pci_core.h | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 3a11e6f450f70105f17a3a621520c195d99e0671..3d70bf6668c7a69c4b46674195954d1ada662006 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1647,7 +1647,7 @@ static unsigned long vma_to_pfn(struct vm_area_struct *vma)
u64 pgoff;

pgoff = vma->vm_pgoff &
- ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
+ ((1UL << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);

return (pci_resource_start(vdev->pdev, index) >> PAGE_SHIFT) + pgoff;
}
@@ -1751,7 +1751,7 @@ int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma
phys_len = PAGE_ALIGN(pci_resource_len(pdev, index));
req_len = vma->vm_end - vma->vm_start;
pgoff = vma->vm_pgoff &
- ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
+ ((1UL << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
req_start = pgoff << PAGE_SHIFT;

if (req_start + req_len > phys_len)
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 1ac86896875cf5c9b5cc8ef25fae8bbd4394de05..12781707f086a330161990dc3579ec0d75887da8 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -20,7 +20,7 @@
#ifndef VFIO_PCI_CORE_H
#define VFIO_PCI_CORE_H

-#define VFIO_PCI_OFFSET_SHIFT 40
+#define VFIO_PCI_OFFSET_SHIFT 48
#define VFIO_PCI_OFFSET_TO_INDEX(off) (off >> VFIO_PCI_OFFSET_SHIFT)
#define VFIO_PCI_INDEX_TO_OFFSET(index) ((u64)(index) << VFIO_PCI_OFFSET_SHIFT)
#define VFIO_PCI_OFFSET_MASK (((u64)(1) << VFIO_PCI_OFFSET_SHIFT) - 1)

--
2.51.0