@@ -175,8 +175,12 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr,
args.address = mmio_addr;
args.vma = vma;
ret = follow_pfnmap_start(&args);
- if (ret)
- goto out_unlock_mmap;
+ if (ret) {
+ fixup_user_fault(current->mm, mmio_addr, FAULT_FLAG_WRITE, NULL);
+ ret = follow_pfnmap_start(&args);
+ if (ret)
+ goto out_unlock_mmap;
+ }
io_addr = (void __iomem *)((args.pfn << PAGE_SHIFT) |
(mmio_addr & ~PAGE_MASK));
@@ -315,14 +319,18 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr,
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
goto out_unlock_mmap;
ret = -EACCES;
- if (!(vma->vm_flags & VM_WRITE))
+ if (!(vma->vm_flags & VM_READ))
goto out_unlock_mmap;
args.vma = vma;
args.address = mmio_addr;
ret = follow_pfnmap_start(&args);
- if (ret)
- goto out_unlock_mmap;
+ if (ret) {
+ fixup_user_fault(current->mm, mmio_addr, 0, NULL);
+ ret = follow_pfnmap_start(&args);
+ if (ret)
+ goto out_unlock_mmap;
+ }
io_addr = (void __iomem *)((args.pfn << PAGE_SHIFT) |
(mmio_addr & ~PAGE_MASK));
The s390 MMIO syscalls when using the classic PCI instructions do not cause a page fault when follow_pfnmap_start() fails due to the page not being present. Besides being a general deficiency this breaks vfio-pci's mmap() handling once VFIO_PCI_MMAP gets enabled as this lazily maps on first access. Fix this by following a failed follow_pfnmap_start() with fixup_user_page() and retrying the follow_pfnmap_start(). Also fix a VM_READ vs VM_WRITE mixup in the read syscall. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> --- arch/s390/pci/pci_mmio.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)