[RFC v1 1/2] drivers/vfio_pci_core: Change PXD_ORDER check from switch case to if/else block

[Ritesh Harjani (IBM)]

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.l...@gmail.com>
---
 drivers/vfio/pci/vfio_pci_core.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index d43745fe4c84..5395a6f30904 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1670,21 +1670,20 @@ 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 == 0) {
                return vmf_insert_pfn(vmf->vma, vmf->address, pfn);
+       }
 #ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP
-       case PMD_ORDER:
+        else if (order == PMD_ORDER) {
                return vmf_insert_pfn_pmd(vmf, pfn, false);
+        }
 #endif
 #ifdef CONFIG_ARCH_SUPPORTS_PUD_PFNMAP
-       case PUD_ORDER:
+        else if (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);

--
2.53.0