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[PULL,19/24] KVM: PPC: Book3S HV: Only accept host PVR value for guest PVR

Message ID 1411591418-56061-20-git-send-email-agraf@suse.de (mailing list archive)
State New, archived
Headers show

Commit Message

Alexander Graf Sept. 24, 2014, 8:43 p.m. UTC 
From: Paul Mackerras <paulus@samba.org>

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>
---
 arch/powerpc/kvm/book3s_hv.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 4526bef..529d10a 100644
--- 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++) {