KVM: s390: protvirt: disallow one_reg

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 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@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 97a72a53fa4b246829d64ebe209724e5d2aee2a9..7505d7a6c0d81380d66e71be0a2b608c25a2c3ed 100644 (file)
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -2117,7 +2117,8 @@ Errors:
 
   ======   ============================================================
   ENOENT   no such register
-  EINVAL   invalid register ID, or no such register
+  EINVAL   invalid register ID, or no such register or used with VMs in
+           protected virtualization mode on s390
   EPERM    (arm64) register access not allowed before vcpu finalization
   ======   ============================================================
 
@@ -2552,7 +2553,8 @@ Errors include:
 
   ======== ============================================================
   ENOENT   no such register
-  EINVAL   invalid register ID, or no such register
+  EINVAL   invalid register ID, or no such register or used with VMs in
+           protected virtualization mode on s390
   EPERM    (arm64) register access not allowed before vcpu finalization
   ======== ============================================================
 

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index efbbcd2948a3b49d7eda77e5c25a40c786156d6f..797b4031ed4d2a854cad52d7f490a640c399cf15 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4674,6 +4674,9 @@ 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_cpu_is_protected(vcpu))
+                       break;
                r = -EFAULT;
                if (copy_from_user(&reg, argp, sizeof(reg)))
                        break;