KVM: protect kvm_usage_count with its own spinlock

The VM list need not be protected by a raw spinlock.  Separate the
two so that kvm_lock can be made non-raw.

Cc: kvm@vger.kernel.org
Cc: gleb@redhat.com
Cc: jan.kiszka@siemens.com
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 10 insertions, 9 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 426051d66173..eb94343c2ed2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -71,6 +71,7 @@ MODULE_LICENSE("GPL");
  */
 
 DEFINE_RAW_SPINLOCK(kvm_lock);
+static DEFINE_RAW_SPINLOCK(kvm_count_lock);
 LIST_HEAD(vm_list);
 
 static cpumask_var_t cpus_hardware_enabled;
@@ -2683,10 +2684,10 @@ static void hardware_enable_nolock(void *junk)
 
 static void hardware_enable(void)
 {
-        raw_spin_lock(&kvm_lock);
+        raw_spin_lock(&kvm_count_lock);
         if (kvm_usage_count)
                 hardware_enable_nolock(NULL);
-        raw_spin_unlock(&kvm_lock);
+        raw_spin_unlock(&kvm_count_lock);
 }
 
 static void hardware_disable_nolock(void *junk)
@@ -2701,10 +2702,10 @@ static void hardware_disable_nolock(void *junk)
 
 static void hardware_disable(void)
 {
-        raw_spin_lock(&kvm_lock);
+        raw_spin_lock(&kvm_count_lock);
         if (kvm_usage_count)
                 hardware_disable_nolock(NULL);
-        raw_spin_unlock(&kvm_lock);
+        raw_spin_unlock(&kvm_count_lock);
 }
 
 static void hardware_disable_all_nolock(void)
@@ -2718,16 +2719,16 @@ static void hardware_disable_all_nolock(void)
 
 static void hardware_disable_all(void)
 {
-        raw_spin_lock(&kvm_lock);
+        raw_spin_lock(&kvm_count_lock);
         hardware_disable_all_nolock();
-        raw_spin_unlock(&kvm_lock);
+        raw_spin_unlock(&kvm_count_lock);
 }
 
 static int hardware_enable_all(void)
 {
         int r = 0;
 
-        raw_spin_lock(&kvm_lock);
+        raw_spin_lock(&kvm_count_lock);
 
         kvm_usage_count++;
         if (kvm_usage_count == 1) {
@@ -2740,7 +2741,7 @@ static int hardware_enable_all(void)
                 }
         }
 
-        raw_spin_unlock(&kvm_lock);
+        raw_spin_unlock(&kvm_count_lock);
 
         return r;
 }
@@ -3130,7 +3131,7 @@ static int kvm_suspend(void)
 static void kvm_resume(void)
 {
         if (kvm_usage_count) {
-                WARN_ON(raw_spin_is_locked(&kvm_lock));
+                WARN_ON(raw_spin_is_locked(&kvm_count_lock));
                 hardware_enable_nolock(NULL);
         }
 }