[PATCH 2/2] KVM: SVM: Notify if SVM is already in use

[Sasha Levin <levinsasha928@gmail.com>]

Currently we silently fail if SVM is already in use by a different
virtualization technology.

This is bad since it's non-obvious for the user, and its not too uncommon
for users to have several of these installed on same host.

This patch adds a message to notify the user of the problem.

Cc: Joerg Roedel <joerg.roedel@amd.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 arch/x86/kvm/svm.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index e32243e..8d1a066 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -587,8 +587,11 @@ static int svm_hardware_enable(void *garbage)
 	int me = raw_smp_processor_id();
 
 	rdmsrl(MSR_EFER, efer);
-	if (efer & EFER_SVME)
+	if (efer & EFER_SVME) {
+		printk(KERN_ERR "svm_hardware_enable: SVM already in use on CPU%d. "
+				"Are you already another hypervisor?\n", me);
 		return -EBUSY;
+	}
 
 	if (!has_svm()) {
 		printk(KERN_ERR "svm_hardware_enable: err EOPNOTSUPP on %d\n",
-- 
1.7.8.rc4