The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x fe752331d4b361d43cfd0b89534b4b2176057c32 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024021903-knapsack-change-c3a4@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
fe752331d4b3 ("KVM: s390: vsie: fix race during shadow creation") c3235e2dd695 ("KVM: s390: add stat counter for shadow gmap events")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From fe752331d4b361d43cfd0b89534b4b2176057c32 Mon Sep 17 00:00:00 2001 From: Christian Borntraeger borntraeger@linux.ibm.com Date: Wed, 20 Dec 2023 13:53:17 +0100 Subject: [PATCH] KVM: s390: vsie: fix race during shadow creation
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;
Let children inherit the private field of the parent.
Reported-by: Marc Hartmayer mhartmay@linux.ibm.com Fixes: a3508fbe9dc6 ("KVM: s390: vsie: initial support for nested virtualization") Cc: stable@vger.kernel.org Cc: David Hildenbrand david@redhat.com Reviewed-by: Janosch Frank frankja@linux.ibm.com Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Claudio Imbrenda imbrenda@linux.ibm.com Signed-off-by: Christian Borntraeger borntraeger@linux.ibm.com Link: https://lore.kernel.org/r/20231220125317.4258-1-borntraeger@linux.ibm.com
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index 8207a892bbe2..db9a180de65f 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -1220,7 +1220,6 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu, gmap = gmap_shadow(vcpu->arch.gmap, asce, edat); if (IS_ERR(gmap)) return PTR_ERR(gmap); - gmap->private = vcpu->kvm; vcpu->kvm->stat.gmap_shadow_create++; WRITE_ONCE(vsie_page->gmap, gmap); return 0; diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 6f96b5a71c63..8da39deb56ca 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -1691,6 +1691,7 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce, return ERR_PTR(-ENOMEM); new->mm = parent->mm; new->parent = gmap_get(parent); + new->private = parent->private; new->orig_asce = asce; new->edat_level = edat_level; new->initialized = false;