[J][PATCH 2/2][v3] KVM: s390: Add a routine for setting userspace CPU state

[frank.heimes at canonical.com]

From: Eric Farman <farman at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1959735

This capability exists, but we don't record anything when userspace
enables it. Let's refactor that code so that a note can be made in
the debug logs that it was enabled.

Signed-off-by: Eric Farman <farman at linux.ibm.com>
Reviewed-by: Thomas Huth <thuth at redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda at linux.ibm.com>
Reviewed-by: David Hildenbrand <david at redhat.com>
Link: https://lore.kernel.org/r/20211008203112.1979843-7-farman@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger at de.ibm.com>
(cherry picked from commit 67cf68b6a5ccac8bc7dfef0a220b59af4c83fd2c)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 arch/s390/kvm/kvm-s390.c | 6 +++---
 arch/s390/kvm/kvm-s390.h | 9 +++++++++
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 5a85bc540ec4..4623eec643ee 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2487,8 +2487,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
 	case KVM_S390_PV_COMMAND: {
 		struct kvm_pv_cmd args;
 
-		/* protvirt means user sigp */
-		kvm->arch.user_cpu_state_ctrl = 1;
+		/* protvirt means user cpu state */
+		kvm_s390_set_user_cpu_state_ctrl(kvm);
 		r = 0;
 		if (!is_prot_virt_host()) {
 			r = -EINVAL;
@@ -3802,7 +3802,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 	vcpu_load(vcpu);
 
 	/* user space knows about this interface - let it control the state */
-	vcpu->kvm->arch.user_cpu_state_ctrl = 1;
+	kvm_s390_set_user_cpu_state_ctrl(vcpu->kvm);
 
 	switch (mp_state->mp_state) {
 	case KVM_MP_STATE_STOPPED:
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 1539dd981104..1876ab0c293f 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -208,6 +208,15 @@ static inline int kvm_s390_user_cpu_state_ctrl(struct kvm *kvm)
 	return kvm->arch.user_cpu_state_ctrl != 0;
 }
 
+static inline void kvm_s390_set_user_cpu_state_ctrl(struct kvm *kvm)
+{
+	if (kvm->arch.user_cpu_state_ctrl)
+		return;
+
+	VM_EVENT(kvm, 3, "%s", "ENABLE: Userspace CPU state control");
+	kvm->arch.user_cpu_state_ctrl = 1;
+}
+
 /* implemented in pv.c */
 int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
 int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
-- 
2.25.1