diff options
| author | Niklas Schnelle <schnelle@linux.ibm.com> | 2025-02-26 13:07:45 +0100 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2025-03-21 14:54:16 -0500 |
| commit | 41a0926e82f4963046876ed9a1b5f681be8087a8 (patch) | |
| tree | b36f2192002cfd1d585c87d90453d7b2fb30927f | |
| parent | 04d50d953ab46d96b0b32d5ad955fceaa28622db (diff) | |
s390/pci: Fix s390_mmio_read/write syscall page fault handling
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.
Link: https://lore.kernel.org/r/20250226-vfio_pci_mmap-v7-1-c5c0f1d26efd@linux.ibm.com
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
| -rw-r--r-- | arch/s390/pci/pci_mmio.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c index 46f99dc164ad..1997d9b7965d 100644 --- a/arch/s390/pci/pci_mmio.c +++ b/arch/s390/pci/pci_mmio.c @@ -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)); |