[SRU][R][PATCH 5/5] KVM: s390: Add KVM capability for ESA mode guests

[Massimiliano Pellizzer]

From: Hendrik Brueckner <brueckner at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/2153159

Now that all the bits are properly addressed, provide a mechanism
for testing ESA mode guests in nested configurations.

Signed-off-by: Hendrik Brueckner <brueckner at linux.ibm.com>
[farman at us.ibm.com: Updated commit message]
Reviewed-by: Janosch Frank <frankja at linux.ibm.com>
Signed-off-by: Eric Farman <farman at linux.ibm.com>
Signed-off-by: Janosch Frank <frankja at linux.ibm.com>
(cherry picked from commit 4aebd7d5c72f805ef59985958ad76b8dbce60d8f)
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 Documentation/virt/kvm/api.rst | 8 ++++++++
 arch/s390/kvm/kvm-s390.c       | 6 ++++++
 include/uapi/linux/kvm.h       | 1 +
 3 files changed, 15 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 032516783e96..feabfee0f714 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -9436,6 +9436,14 @@ KVM exits with the register state of either the L1 or L2 guest
 depending on which executed at the time of an exit. Userspace must
 take care to differentiate between these cases.
 
+8.47 KVM_CAP_S390_VSIE_ESAMODE
+------------------------------
+
+:Architectures: s390
+
+The presence of this capability indicates that the nested KVM guest can
+start in ESA mode.
+
 9. Known KVM API problems
 =========================
 
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index d7838334a338..3856af54b6fe 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -629,6 +629,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_IRQFD_RESAMPLE:
 	case KVM_CAP_S390_USER_OPEREXEC:
 	case KVM_CAP_S390_KEYOP:
+	case KVM_CAP_S390_VSIE_ESAMODE:
 		r = 1;
 		break;
 	case KVM_CAP_SET_GUEST_DEBUG2:
@@ -926,6 +927,11 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
 		icpt_operexc_on_all_vcpus(kvm);
 		r = 0;
 		break;
+	case KVM_CAP_S390_VSIE_ESAMODE:
+		VM_EVENT(kvm, 3, "%s", "ENABLE: CAP_S390_VSIE_ESAMODE");
+		kvm->arch.allow_vsie_esamode = 1;
+		r = 0;
+		break;
 	default:
 		r = -EINVAL;
 		break;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3f0d8d3c3daf..3dc7d9bf3c09 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -990,6 +990,7 @@ struct kvm_enable_cap {
 #define KVM_CAP_ARM_SEA_TO_USER 245
 #define KVM_CAP_S390_USER_OPEREXEC 246
 #define KVM_CAP_S390_KEYOP 247
+#define KVM_CAP_S390_VSIE_ESAMODE 248
 
 struct kvm_irq_routing_irqchip {
 	__u32 irqchip;
-- 
2.53.0