diff options
| -rw-r--r-- | arch/s390/pci/pci_mmio.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c index 38efa3e852c4..401cf670a243 100644 --- a/arch/s390/pci/pci_mmio.c +++ b/arch/s390/pci/pci_mmio.c @@ -155,10 +155,12 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, unsigned long, mmio_addr, return -EINVAL; /* - * Only support read access to MIO capable devices on a MIO enabled - * system. Otherwise we would have to check for every address if it is - * a special ZPCI_ADDR and we would have to do a get_pfn() which we - * don't need for MIO capable devices. + * We only support write access to MIO capable devices if we are on + * a MIO enabled system. Otherwise we would have to check for every + * address if it is a special ZPCI_ADDR and would have to do + * a get_pfn() which we don't need for MIO capable devices. Currently + * ISM devices are the only devices without MIO support and there is no + * known need for accessing these from userspace. */ if (static_branch_likely(&have_mio)) { ret = __memcpy_toio_inuser((void __iomem *) mmio_addr, @@ -282,10 +284,12 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsigned long, mmio_addr, return -EINVAL; /* - * Only support write access to MIO capable devices on a MIO enabled - * system. Otherwise we would have to check for every address if it is - * a special ZPCI_ADDR and we would have to do a get_pfn() which we - * don't need for MIO capable devices. + * We only support read access to MIO capable devices if we are on + * a MIO enabled system. Otherwise we would have to check for every + * address if it is a special ZPCI_ADDR and would have to do + * a get_pfn() which we don't need for MIO capable devices. Currently + * ISM devices are the only devices without MIO support and there is no + * known need for accessing these from userspace. */ if (static_branch_likely(&have_mio)) { ret = __memcpy_fromio_inuser( |