Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6031a61c2ef4cf22b69ef5494aefa54b84a27d2f
Commit:     6031a61c2ef4cf22b69ef5494aefa54b84a27d2f
Parent:     796fd1b23e463e98b3e2fc86ed571db06dc945bb
Author:     Joerg Roedel <[EMAIL PROTECTED]>
AuthorDate: Fri Jun 22 12:29:50 2007 +0300
Committer:  Avi Kivity <[EMAIL PROTECTED]>
CommitDate: Mon Jul 16 12:05:49 2007 +0300

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
---
 drivers/kvm/svm.c |    6 ++++++
 drivers/kvm/svm.h |    3 +++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 62ec38c..a0d4428 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;
 }
 
diff --git a/drivers/kvm/svm.h b/drivers/kvm/svm.h
index 5e93814..3b1b0f3 100644
--- a/drivers/kvm/svm.h
+++ b/drivers/kvm/svm.h
@@ -175,8 +175,11 @@ struct __attribute__ ((__packed__)) vmcb {
 #define SVM_CPUID_FUNC 0x8000000a
 
 #define MSR_EFER_SVME_MASK (1ULL << 12)
+#define MSR_VM_CR       0xc0010114
 #define MSR_VM_HSAVE_PA 0xc0010117ULL
 
+#define SVM_VM_CR_SVM_DISABLE 4
+
 #define SVM_SELECTOR_S_SHIFT 4
 #define SVM_SELECTOR_DPL_SHIFT 5
 #define SVM_SELECTOR_P_SHIFT 7
-
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