iommu/io-pgtable: depend on !GENERIC_ATOMIC64 when using COMPILE_TEST with LPAE

The LPAE/ARMv8 page table format relies on the ability to read and write
64-bit page table entries in an atomic fashion. With the move to a lockless
implementation, we also need support for cmpxchg64 to resolve races when
installing table entries concurrently.

Unfortunately, not all architectures support cmpxchg64, so the code can
fail to compiler when building for these architectures using COMPILE_TEST.
Rather than disable COMPILE_TEST altogether, instead check that
GENERIC_ATOMIC64 is not selected, which is a reasonable indication that
the architecture has support for 64-bit cmpxchg.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 6ee3a25ae731880147e5b5986b8f2e188e2bf687..c88cfa7522b273d5b8c32ac8534e126e79fc0b09 100644 (file)
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -23,7 +23,7 @@ config IOMMU_IO_PGTABLE
 config IOMMU_IO_PGTABLE_LPAE
        bool "ARMv7/v8 Long Descriptor Format"
        select IOMMU_IO_PGTABLE
-       depends on HAS_DMA && (ARM || ARM64 || COMPILE_TEST)
+       depends on HAS_DMA && (ARM || ARM64 || (COMPILE_TEST && !GENERIC_ATOMIC64))
        help
          Enable support for the ARM long descriptor pagetable format.
          This allocator supports 4K/2M/1G, 16K/32M and 64K/512M page