From bad94d3d18c600cfe2c24c17b1825db4b8795e3e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= Date: Mon, 20 Jul 2026 20:46:24 +0000 Subject: [PATCH] PCI/sysfs: Return -EINVAL for unsupported I/O BAR mmap MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, mmap() of a resourceN file for an I/O BAR fails with -ENODEV on architectures where arch_can_pci_mmap_io() is 0, such as x86, because the attribute has no mmap callback there and the error comes from the generic kernfs dispatch. This is a side effect of commit e854d8b2a82e ("PCI: Add arch_can_pci_mmap_io() on architectures which can mmap() I/O space"), which removed the mmap callback from the I/O resource attribute on these architectures. Previously the request reached the architecture mmap code and failed with -EINVAL, and the same commit deliberately kept -EINVAL for the identical operation on the procfs interface, so the two PCI userspace interfaces have disagreed ever since. Add a pci_mmap_resource_io_unsupported() callback that returns -EINVAL and use it as the mmap handler of the I/O resource attribute when arch_can_pci_mmap_io() is 0, so the failure is produced deliberately by PCI code, consistent with the procfs interface and with the behaviour before e854d8b2a82e. Architectures where arch_can_pci_mmap_io() is non-zero keep the real pci_mmap_resource_uc() handler and are unaffected. The mmap() fails either way. Only the reported error changes from -ENODEV to -EINVAL. Fixes: e854d8b2a82e ("PCI: Add arch_can_pci_mmap_io() on architectures which can mmap() I/O space") Signed-off-by: Krzysztof Wilczyński Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20260720204624.1503794-1-kwilczynski@kernel.org --- drivers/pci/pci-sysfs.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 1be627913a9b..eab14be6fcf1 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -1274,7 +1274,16 @@ static loff_t pci_llseek_resource(struct file *filep, .llseek = pci_llseek_resource, \ .mmap = pci_mmap_resource_uc, #else -# define __PCI_RESOURCE_IO_MMAP_ATTRS +static int pci_mmap_resource_io_unsupported(struct file *filp, + struct kobject *kobj, + const struct bin_attribute *attr, + struct vm_area_struct *vma) +{ + return -EINVAL; +} + +# define __PCI_RESOURCE_IO_MMAP_ATTRS \ + .mmap = pci_mmap_resource_io_unsupported, #endif #define pci_dev_resource_io_attr(_bar) \