KVM: Add API to retrieve the number of supported vcpus per vm

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

2 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 256c0fc92b67..955d2eeac964 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -811,6 +811,9 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_VAPIC:
                 r = !kvm_x86_ops->cpu_has_accelerated_tpr();
                 break;
+        case KVM_CAP_NR_VCPUS:
+                r = KVM_MAX_VCPUS;
+                break;
         default:
                 r = 0;
                 break;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 94540b3c6872..deb9c38f98e7 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -234,6 +234,7 @@ struct kvm_vapic_addr {
 #define KVM_CAP_VAPIC 6
 #define KVM_CAP_EXT_CPUID 7
 #define KVM_CAP_CLOCKSOURCE 8
+#define KVM_CAP_NR_VCPUS 9       /* returns max vcpus per vm */
 
 /*
  * ioctls for VM fds