KVM: SVM: Reliably detect if SVM was disabled by BIOS

This patch adds an implementation to the svm is_disabled function to
detect reliably if the BIOS disabled the SVM feature in the CPU. This
fixes the issues with kernel panics when loading the kvm-amd module on
machines where SVM is available but disabled.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 62ec38c7027b..a0d442883e17 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -1735,6 +1735,12 @@ static void svm_inject_page_fault(struct kvm_vcpu *vcpu,
 
 static int is_disabled(void)
 {
+        u64 vm_cr;
+
+        rdmsrl(MSR_VM_CR, vm_cr);
+        if (vm_cr & (1 << SVM_VM_CR_SVM_DISABLE))
+                return 1;
+
         return 0;
 }