KVM: Add per-vm capability enablement.

Allow KVM_ENABLE_CAP to act on a vm as well as on a vcpu. This makes more
sense when the caller wants to enable a vm-related capability.

s390 will be the first user; wire it up.

Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

Documentation/virtual/kvm/api.txt

@@ -932,9 +932,9 @@ documentation when it pops into existence).
 
 4.37 KVM_ENABLE_CAP
 
-Capability: KVM_CAP_ENABLE_CAP
+Capability: KVM_CAP_ENABLE_CAP, KVM_CAP_ENABLE_CAP_VM
 Architectures: ppc, s390
-Type: vcpu ioctl
+Type: vcpu ioctl, vm ioctl (with KVM_CAP_ENABLE_CAP_VM)
 Parameters: struct kvm_enable_cap (in)
 Returns: 0 on success; -1 on error
 
@@ -965,6 +965,8 @@ function properly, this is the place to put them.
        __u8  pad[64];
 };
 
+The vcpu ioctl should be used for vcpu-specific capabilities, the vm ioctl
+for vm-wide capabilities.
 
 4.38 KVM_GET_MP_STATE
 

arch/s390/kvm/kvm-s390.c

@@ -159,6 +159,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_S390_CSS_SUPPORT:
 	case KVM_CAP_IOEVENTFD:
 	case KVM_CAP_DEVICE_CTRL:
+	case KVM_CAP_ENABLE_CAP_VM:
 		r = 1;
 		break;
 	case KVM_CAP_NR_VCPUS:
@@ -187,6 +188,21 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 	return 0;
 }
 
+static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
+{
+	int r;
+
+	if (cap->flags)
+		return -EINVAL;
+
+	switch (cap->cap) {
+	default:
+		r = -EINVAL;
+		break;
+	}
+	return r;
+}
+
 long kvm_arch_vm_ioctl(struct file *filp,
 		       unsigned int ioctl, unsigned long arg)
 {
@@ -204,6 +220,14 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		r = kvm_s390_inject_vm(kvm, &s390int);
 		break;
 	}
+	case KVM_ENABLE_CAP: {
+		struct kvm_enable_cap cap;
+		r = -EFAULT;
+		if (copy_from_user(&cap, argp, sizeof(cap)))
+			break;
+		r = kvm_vm_ioctl_enable_cap(kvm, &cap);
+		break;
+	}
 	default:
 		r = -ENOTTY;
 	}

include/uapi/linux/kvm.h

@@ -741,6 +741,7 @@ struct kvm_ppc_smmu_info {
 #define KVM_CAP_EXT_EMUL_CPUID 95
 #define KVM_CAP_HYPERV_TIME 96
 #define KVM_CAP_IOAPIC_POLARITY_IGNORED 97
+#define KVM_CAP_ENABLE_CAP_VM 98
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
@@ -1076,6 +1077,10 @@ struct kvm_s390_ucas_mapping {
 /* Available with KVM_CAP_DEBUGREGS */
 #define KVM_GET_DEBUGREGS         _IOR(KVMIO,  0xa1, struct kvm_debugregs)
 #define KVM_SET_DEBUGREGS         _IOW(KVMIO,  0xa2, struct kvm_debugregs)
+/*
+ * vcpu version available with KVM_ENABLE_CAP
+ * vm version available with KVM_CAP_ENABLE_CAP_VM
+ */
 #define KVM_ENABLE_CAP            _IOW(KVMIO,  0xa3, struct kvm_enable_cap)
 /* Available with KVM_CAP_XSAVE */
 #define KVM_GET_XSAVE		  _IOR(KVMIO,  0xa4, struct kvm_xsave)