Re: [PATCH] KVM: s390: vsie: fix race during shadow creation

Christian Borntraeger <borntraeger@xxxxxxxxxxxxx> · Wed, 20 Dec 2023 08:35:24 +0100

Am 20.12.23 um 08:34 schrieb Christian Borntraeger:
Right now it is possible to see gmap->private being zero in
kvm_s390_vsie_gmap_notifier resulting in a crash.  This is due to the
fact that we add gmap->private == kvm after creation:

static int acquire_gmap_shadow(struct kvm_vcpu *vcpu,
                                struct vsie_page *vsie_page)
{
[...]
         gmap = gmap_shadow(vcpu->arch.gmap, asce, edat);
         if (IS_ERR(gmap))
                 return PTR_ERR(gmap);
         gmap->private = vcpu->kvm;

Instead of tracking kvm in the shadow gmap, simply use the parent one.

Cc: David Hildenbrand <david@xxxxxxxxxx>

I forgot to add
Reported-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>