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authorSean Christopherson <seanjc@google.com>2023-11-29 16:10:00 -0800
committerAlex Williamson <alex.williamson@redhat.com>2023-11-30 11:27:17 -0700
commit4ea95c04fa6b9043a1a301240996aeebe3cb28ec (patch)
treebc704ed33cd77165e4fb42d64c83fec05af62b0b
parentae2667cd8a479bb5abd6e24c12fcc9ef5bc06d75 (diff)
vfio: Drop vfio_file_iommu_group() stub to fudge around a KVM wart
Drop the vfio_file_iommu_group() stub and instead unconditionally declare the function to fudge around a KVM wart where KVM tries to do symbol_get() on vfio_file_iommu_group() (and other VFIO symbols) even if CONFIG_VFIO=n. Ensuring the symbol is always declared fixes a PPC build error when modules are also disabled, in which case symbol_get() simply points at the address of the symbol (with some attributes shenanigans). Because KVM does symbol_get() instead of directly depending on VFIO, the lack of a fully defined symbol is not problematic (ugly, but "fine"). arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition [-Werror,-Wignored-attributes] fn = symbol_get(vfio_file_iommu_group); ^ include/linux/module.h:805:60: note: expanded from macro 'symbol_get' #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); }) ^ include/linux/vfio.h:294:35: note: previous definition is here static inline struct iommu_group *vfio_file_iommu_group(struct file *file) ^ arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition [-Werror,-Wignored-attributes] fn = symbol_get(vfio_file_iommu_group); ^ include/linux/module.h:805:65: note: expanded from macro 'symbol_get' #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); }) ^ include/linux/vfio.h:294:35: note: previous definition is here static inline struct iommu_group *vfio_file_iommu_group(struct file *file) ^ 2 errors generated. Although KVM is firmly in the wrong (there is zero reason for KVM to build virt/kvm/vfio.c when VFIO is disabled), fudge around the error in VFIO as the stub is unnecessary and doesn't serve its intended purpose (KVM is the only external user of vfio_file_iommu_group()), and there is an in-flight series to clean up the entire KVM<->VFIO interaction, i.e. fixing this in KVM would result in more churn in the long run, and the stub needs to go away regardless. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202308251949.5IiaV0sz-lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202309030741.82aLACDG-lkp@intel.com Closes: https://lore.kernel.org/oe-kbuild-all/202309110914.QLH0LU6L-lkp@intel.com Link: https://lore.kernel.org/all/0-v1-08396538817d+13c5-vfio_kvm_kconfig_jgg@nvidia.com Link: https://lore.kernel.org/all/20230916003118.2540661-1-seanjc@google.com Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Tested-by: Michael Ellerman <mpe@ellerman.id.au> Fixes: c1cce6d079b8 ("vfio: Compile vfio_group infrastructure optionally") Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/20231130001000.543240-1-seanjc@google.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
-rw-r--r--include/linux/vfio.h8
1 files changed, 2 insertions, 6 deletions
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 454e9295970c..a65b2513f8cd 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -289,16 +289,12 @@ void vfio_combine_iova_ranges(struct rb_root_cached *root, u32 cur_nodes,
/*
* External user API
*/
-#if IS_ENABLED(CONFIG_VFIO_GROUP)
struct iommu_group *vfio_file_iommu_group(struct file *file);
+
+#if IS_ENABLED(CONFIG_VFIO_GROUP)
bool vfio_file_is_group(struct file *file);
bool vfio_file_has_dev(struct file *file, struct vfio_device *device);
#else
-static inline struct iommu_group *vfio_file_iommu_group(struct file *file)
-{
- return NULL;
-}
-
static inline bool vfio_file_is_group(struct file *file)
{
return false;