Revert "kvm: external module: kvm no longer depends on mm_count and mmdrop()"kvm-64rc2kvm-64

This reverts commit 14795bc960af5ef7286dd7207023abf28fbc118f.  Needed again
as 202761268a29d4cd3a3fec35e6d6f2f239374635 was reverted in kvm.git.

Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 16 insertions, 0 deletions

diff --git a/kvm/kernel/external-module-compat.h b/kvm/kernel/external-module-compat.h
index e164eec75..98ed13f26 100644
--- a/kvm/kernel/external-module-compat.h
+++ b/kvm/kernel/external-module-compat.h
@@ -534,6 +534,20 @@ static inline void blahblah(void)
 	(void)empty_zero_page[0];
 }
 
+/* __mmdrop() is not exported before 2.6.25 */
+#include <linux/sched.h>
+
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,25)
+
+#define mmdrop(x) do { (void)(x); } while (0)
+#define mmget(x) do { (void)(x); } while (0)
+
+#else
+
+#define mmget(x) do { atomic_inc(x); } while (0)
+
+#endif
+
 /* X86_FEATURE_NX is missing in some x86_64 kernels */
 
 #include <asm/cpufeature.h>
diff --git a/kvm/kernel/hack-module.awk b/kvm/kernel/hack-module.awk
index dd9a2f403..455e662cf 100644
--- a/kvm/kernel/hack-module.awk
+++ b/kvm/kernel/hack-module.awk
@@ -33,6 +33,8 @@
     vmx_load_host_state = 0
 }
 
+/atomic_inc\(&kvm->mm->mm_count\);/ { $0 = "mmget(&kvm->mm->mm_count);" }
+
 /^\t\.fault = / {
     fcn = gensub(/,/, "", "g", $3)
     $0 = "\t.VMA_OPS_FAULT(fault) = VMA_OPS_FAULT_FUNC(" fcn "),"