KVM: MMU: large page support

Create large pages mappings if the guest PTE's are marked as such and
the underlying memory is hugetlbfs backed.  If the largepage contains
write-protected pages, a large pte is not used.

Gives a consistent 2% improvement for data copies on ram mounted
filesystem, without NPT/EPT.

Anthony measures a 4% improvement on 4-way kernbench, with NPT.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e8e64927bddc..0458bd516185 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -88,6 +88,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
         { "mmu_recycled", VM_STAT(mmu_recycled) },
         { "mmu_cache_miss", VM_STAT(mmu_cache_miss) },
         { "remote_tlb_flush", VM_STAT(remote_tlb_flush) },
+        { "largepages", VM_STAT(lpages) },
         { NULL }
 };