On Mon, 3 Feb 2020 08:19:46 -0500
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
> From: Janosch Frank <frankja@xxxxxxxxxxxxx>
>
> A lot of the registers are controlled by the Ultravisor and never
> visible to KVM. Some fields in the sie control block are overlayed,
> like gbea. As no userspace uses the ONE_REG interface on s390 it is safe
> to disable this for protected guests.
Hm, QEMU seems to fall back to ONE_REG if sync regs are not available,
doesn't it? So maybe it would be better to word this as
"As no known userspace uses the ONE_REG interface on s390 if sync regs
are available, no functionality is lost if it is disabled for protected
guests."
?
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 6e74c7afae3a..b9692d722c1e 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -4641,6 +4641,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> case KVM_SET_ONE_REG:
> case KVM_GET_ONE_REG: {
> struct kvm_one_reg reg;
> + r = -EINVAL;
> + if (kvm_s390_pv_is_protected(vcpu->kvm))
> + break;
> r = -EFAULT;
> if (copy_from_user(®, argp, sizeof(reg)))
> break;
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
