KVM: move KVM_CAP_DEVICE_CTRL to the generic check

KVM_CAP_DEVICE_CTRL allows userspace to check if the kvm_device
framework (e.g. KVM_CREATE_DEVICE) is supported by KVM. Move
KVM_CAP_DEVICE_CTRL to the generic check for the two reasons:
1) it already supports arch agnostic usages (i.e. KVM_DEV_TYPE_VFIO).
For example, userspace VFIO implementation may needs to create
KVM_DEV_TYPE_VFIO on x86, riscv, or arm etc. It is simpler to have it
checked at the generic code than at each arch's code.
2) KVM_CREATE_DEVICE has been added to the generic code.

Link: https://lore.kernel.org/all/20221215115207.14784-1-wei.w.wang@intel.com
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Acked-by: Anup Patel <anup@brainfault.org> (riscv)
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://lore.kernel.org/r/20230315101606.10636-1-wei.w.wang@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/arm64/kvm/arm.c

@@ -221,7 +221,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = vgic_present;
 		break;
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_SYNC_MMU:
 	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:

arch/powerpc/kvm/powerpc.c

@@ -528,7 +528,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_ONE_REG:
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_IMMEDIATE_EXIT:
 	case KVM_CAP_SET_GUEST_DEBUG:
 		r = 1;

arch/riscv/kvm/vm.c

@@ -179,7 +179,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		r = kvm_riscv_aia_available();
 		break;
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_USER_MEMORY:
 	case KVM_CAP_SYNC_MMU:
 	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:

arch/s390/kvm/kvm-s390.c

@@ -563,7 +563,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_ENABLE_CAP:
 	case KVM_CAP_S390_CSS_SUPPORT:
 	case KVM_CAP_IOEVENTFD:
-	case KVM_CAP_DEVICE_CTRL:
 	case KVM_CAP_S390_IRQCHIP:
 	case KVM_CAP_VM_ATTRIBUTES:
 	case KVM_CAP_MP_STATE:

virt/kvm/kvm_main.c

@@ -4873,6 +4873,7 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 #endif
 	case KVM_CAP_BINARY_STATS_FD:
 	case KVM_CAP_SYSTEM_EVENT_DATA:
+	case KVM_CAP_DEVICE_CTRL:
 		return 1;
 #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES
 	case KVM_CAP_MEMORY_ATTRIBUTES: