KVM: PPC: Book3S HV: Only accept host PVR value for guest PVR

Since the guest can read the machine's PVR (Processor Version Register)
directly and see the real value, we should disallow userspace from
setting any value for the guest's PVR other than the real host value.
Therefore this makes kvm_arch_vcpu_set_sregs_hv() check the supplied
PVR value and return an error if it is different from the host value,
which has been put into vcpu->arch.pvr at vcpu creation time.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 4526befd60c5e31bc540383e5bbb1790fdfbfe2b..529d10a7a36f025ce59ba1abbc73e9b7ce20e508 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -856,7 +856,9 @@ static int kvm_arch_vcpu_ioctl_set_sregs_hv(struct kvm_vcpu *vcpu,
 {
        int i, j;
 
-       kvmppc_set_pvr_hv(vcpu, sregs->pvr);
+       /* Only accept the same PVR as the host's, since we can't spoof it */
+       if (sregs->pvr != vcpu->arch.pvr)
+               return -EINVAL;
 
        j = 0;
        for (i = 0; i < vcpu->arch.slb_nr; i++) {