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 f615af4525656bc3961a79149dbe3e9cfcc5084f..1185b556653b2cca5e60d58b080db6f43c481c37 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1854,6 +1854,9 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
                svm->vmcb->control.intercept_cr_write &= ~INTERCEPT_CR8_MASK;
        }
 
+       /* 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 |=