lkml.org 
[lkml]   [2024]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 6.6 52/60] KVM: s390: vsie: fix race during shadow creation
Date
From: Christian Borntraeger <borntraeger@linux.ibm.com>

[ Upstream commit fe752331d4b361d43cfd0b89534b4b2176057c32 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kvm/vsie.c | 1 -
arch/s390/mm/gmap.c | 1 +
2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 8207a892bbe22..db9a180de65f1 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 20786f6883b29..157e0a8d5157d 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;
--
2.43.0

\
 
 \ /
  Last update: 2024-03-13 18:00    [W:0.223 / U:0.684 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site