Re: [PATCH v2 1/2] drivers/vfio_pci_core: Change PXD_ORDER check from switch case to if/else block
From: Venkat <hidden>
Date: 2026-03-10 06:28:15
Also in:
kvm, linux-mm
On 9 Mar 2026, at 6:08 PM, Ritesh Harjani (IBM) [off-list ref] wrote:
Architectures like PowerPC uses runtime defined values for
PMD_ORDER/PUD_ORDER. This is because it can use either RADIX or HASH MMU
at runtime using kernel cmdline. So the pXd_index_size is not known at
compile time. Without this fix, when we add huge pfn support on powerpc
in the next patch, vfio_pci_core driver compilation can fail with the
following errors.
CC [M] drivers/vfio/vfio_main.o
CC [M] drivers/vfio/group.o
CC [M] drivers/vfio/container.o
CC [M] drivers/vfio/virqfd.o
CC [M] drivers/vfio/vfio_iommu_spapr_tce.o
CC [M] drivers/vfio/pci/vfio_pci_core.o
CC [M] drivers/vfio/pci/vfio_pci_intrs.o
CC [M] drivers/vfio/pci/vfio_pci_rdwr.o
CC [M] drivers/vfio/pci/vfio_pci_config.o
CC [M] drivers/vfio/pci/vfio_pci.o
AR kernel/built-in.a
../drivers/vfio/pci/vfio_pci_core.c: In function ‘vfio_pci_vmf_insert_pfn’:
../drivers/vfio/pci/vfio_pci_core.c:1678:9: error: case label does not reduce to an integer constant
1678 | case PMD_ORDER:
| ^~~~
../drivers/vfio/pci/vfio_pci_core.c:1682:9: error: case label does not reduce to an integer constant
1682 | case PUD_ORDER:
| ^~~~
make[6]: *** [../scripts/Makefile.build:289: drivers/vfio/pci/vfio_pci_core.o] Error 1
make[6]: *** Waiting for unfinished jobs....
make[5]: *** [../scripts/Makefile.build:546: drivers/vfio/pci] Error 2
make[5]: *** Waiting for unfinished jobs....
make[4]: *** [../scripts/Makefile.build:546: drivers/vfio] Error 2
make[3]: *** [../scripts/Makefile.build:546: drivers] Error 2
Fixes: f9e54c3a2f5b7 ("vfio/pci: implement huge_fault support")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
---
Tested-by: Venkat Rao Bagalkote <redacted>
Tested this patch, and with this, build is successful and reported issue is fixed.
WithOut this patch:
drivers/vfio/pci/vfio_pci_core.c: In function ‘vfio_pci_vmf_insert_pfn’:
drivers/vfio/pci/vfio_pci_core.c:1677:9: error: case label does not reduce to an integer constant
1677 | case PMD_ORDER:
| ^~~~
drivers/vfio/pci/vfio_pci_core.c:1681:9: error: case label does not reduce to an integer constant
1681 | case PUD_ORDER:
| ^~~~
Regards,
Venkat.quoted hunk ↗ jump to hunk
v1 -> v2: 1. addressed review comments from Christophe [1] [1]: https://lore.kernel.org/linuxppc-dev/0b8fce7a61561640634317a5e287cdb4794715fd.1772170860.git.ritesh.list@gmail.com/ (local) drivers/vfio/pci/vfio_pci_core.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index d43745fe4c84..0967307235b8 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c@@ -1670,21 +1670,16 @@ vm_fault_t vfio_pci_vmf_insert_pfn(struct vfio_pci_core_device *vdev,if (vdev->pm_runtime_engaged || !__vfio_pci_memory_enabled(vdev)) return VM_FAULT_SIGBUS; - switch (order) { - case 0: + if (!order) return vmf_insert_pfn(vmf->vma, vmf->address, pfn); -#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP - case PMD_ORDER: + + if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_PMD_PFNMAP) && order == PMD_ORDER) return vmf_insert_pfn_pmd(vmf, pfn, false); -#endif -#ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP - case PUD_ORDER: + + if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_PUD_PFNMAP) && order == PUD_ORDER) return vmf_insert_pfn_pud(vmf, pfn, false); - break; -#endif - default: - return VM_FAULT_FALLBACK; - } + + return VM_FAULT_FALLBACK; } EXPORT_SYMBOL_GPL(vfio_pci_vmf_insert_pfn); -- 2.39.5