FAILED: patch "[PATCH] KVM: s390: vsie: fix race during shadow creation" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-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 <[email protected]>.

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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x fe752331d4b361d43cfd0b89534b4b2176057c32
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024021904-gestate-update-2b10@gregkh' --subject-prefix 'PATCH 6.1.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 <[email protected]>
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.

index 8207a892bbe2..db9a180de65f 100644
@@ -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;

index 6f96b5a71c63..8da39deb56ca 100644
@@ -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;