[RFCv2 26/37] KVM: s390: protvirt: disallow one_reg

[Christian Borntraeger <borntraeger@xxxxxxxxxx>]

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.

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(&reg, argp, sizeof(reg)))
 			break;
-- 
2.24.0