mmu_gather: Remove per arch tlb_{start,end}_vma()

Scattered across the archs are 3 basic forms of tlb_{start,end}_vma().
Provide two new MMU_GATHER_knobs to enumerate them and remove the per
arch tlb_{start,end}_vma() implementations.

 - MMU_GATHER_NO_FLUSH_CACHE indicates the arch has flush_cache_range()
   but does *NOT* want to call it for each VMA.

 - MMU_GATHER_MERGE_VMAS indicates the arch wants to merge the
   invalidate across multiple VMAs if possible.

With these it is possible to capture the three forms:

  1) empty stubs;
     select MMU_GATHER_NO_FLUSH_CACHE and MMU_GATHER_MERGE_VMAS

  2) start: flush_cache_range(), end: empty;
     select MMU_GATHER_MERGE_VMAS

  3) start: flush_cache_range(), end: flush_tlb_range();
     default

Obviously, if the architecture does not have flush_cache_range() then
it also doesn't need to select MMU_GATHER_NO_FLUSH_CACHE.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 8cd9e56c629b..5a1a8dfda6f8 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -204,6 +204,7 @@ config S390
 	select IOMMU_SUPPORT		if PCI
 	select MMU_GATHER_NO_GATHER
 	select MMU_GATHER_RCU_TABLE_FREE
+	select MMU_GATHER_MERGE_VMAS
 	select MODULES_USE_ELF_RELA
 	select NEED_DMA_MAP_STATE	if PCI
 	select NEED_SG_DMA_LENGTH	if PCI