From: Janosch Frank <frankja@linux.ibm.com>
Date: Fri, 14 Jun 2019 13:11:21 +0200
Subject: KVM: s390: protvirt: disallow one_reg
Git-commit: 68cf7b1f137e61cea71925e48bc0c6d7bcfc637c
Patch-mainline: v5.7-rc1
References: jsc#SLE-7512 bsc#1165545

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>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 Documentation/virt/kvm/api.txt |   16 ++++++++++------
 arch/s390/kvm/kvm-s390.c       |    3 +++
 2 files changed, 13 insertions(+), 6 deletions(-)

--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -1892,9 +1892,11 @@ Type: vcpu ioctl
 Parameters: struct kvm_one_reg (in)
 Returns: 0 on success, negative value on failure
 Errors:
-  ENOENT:   no such register
-  EINVAL:   invalid register ID, or no such register
-  EPERM:    (arm64) register access not allowed before vcpu finalization
+  ENOENT   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
+
 (These error codes are indicative only: do not rely on a specific error
 code being returned in a specific situation.)
 
@@ -2285,9 +2287,11 @@ Type: vcpu ioctl
 Parameters: struct kvm_one_reg (in and out)
 Returns: 0 on success, negative value on failure
 Errors include:
-  ENOENT:   no such register
-  EINVAL:   invalid register ID, or no such register
-  EPERM:    (arm64) register access not allowed before vcpu finalization
+  ENOENT   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
+
 (These error codes are indicative only: do not rely on a specific error
 code being returned in a specific situation.)
 
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4681,6 +4681,9 @@ long kvm_arch_vcpu_ioctl(struct file *fi
 	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;