On Thu, 15 Apr 2021 10:01:27 +0200
Heiko Carstens <hca@xxxxxxxxxxxxx> wrote:
> store_regs_fmt2() has an ordering problem: first the guarded storage
> facility is enabled on the local cpu, then preemption disabled, and
> then the STGSC (store guarded storage controls) instruction is
> executed.
>
> If the process gets scheduled away between enabling the guarded
> storage facility and before preemption is disabled, this might lead to
> a special operation exception and therefore kernel crash as soon as
> the process is scheduled back and the STGSC instruction is executed.
>
> Fixes: 4e0b1ab72b8a ("KVM: s390: gs support for kvm guests")
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.12
> Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
