KVM: SVM: Don't allow nested guest to VMMCALL into host

This patch disables the possibility for a l2-guest to do a
VMMCALL directly into the host. This would happen if the
l1-hypervisor doesn't intercept VMMCALL and the l2-guest
executes this instruction.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
(cherry picked from commit 0d945bd9351199744c1e89d57a70615b6ee9f394)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 9b99342d75fdb746ee9d07a581efd1186c8bbeb2..a2f839cbad0161bac1d3ecf687662e55d9afe236 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1829,8 +1829,13 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
                svm->vmcb->control.intercept_cr_write &= ~INTERCEPT_CR8_MASK;
        }
 
-       /* We don't want a nested guest to be more powerful than the guest,
-          so all intercepts are ORed */
+       /* We don't want to see VMMCALLs from a nested guest */
+       svm->vmcb->control.intercept &= ~(1ULL << INTERCEPT_VMMCALL);
+
+       /*
+        * We don't want a nested guest to be more powerful than the guest, so
+        * all intercepts are ORed
+        */
        svm->vmcb->control.intercept_cr_read |=
                nested_vmcb->control.intercept_cr_read;
        svm->vmcb->control.intercept_cr_write |=