diff options
| author | Niklas Schnelle <schnelle@linux.ibm.com> | 2025-02-26 13:07:45 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-20 10:15:28 +0200 |
| commit | 43e5e2879deecc286f2859791e7c795969aa4335 (patch) | |
| tree | e1b01e0c01852cd872c29965d0031aa77e77d847 | |
| parent | dd3edffae868f34e494656245786de888189d2de (diff) | |
s390/pci: Fix s390_mmio_read/write syscall page fault handling
[ Upstream commit 41a0926e82f4963046876ed9a1b5f681be8087a8 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -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 de5c0b389a3e..4779c3cb6cfa 100644 --- a/arch/s390/pci/pci_mmio.c +++ b/arch/s390/pci/pci_mmio.c @@ -171,8 +171,12 @@ 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)); @@ -305,14 +309,18 @@ 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)); |