KVM: x86: leave kvm.ko out of the build if no vendor module is requested

kvm.ko is nothing but library code shared by kvm-intel.ko and kvm-amd.ko.
It provides no functionality on its own and it is unnecessary unless one
of the vendor-specific module is compiled.  In particular, /dev/kvm is
not created until one of kvm-intel.ko or kvm-amd.ko is loaded.

Use CONFIG_KVM to decide if it is built-in or a module, but use the
vendor-specific modules for the actual decision on whether to build it.

This also fixes a build failure when CONFIG_KVM_INTEL and CONFIG_KVM_AMD
are both disabled.  The cpu_emergency_register_virt_callback() function
is called from kvm.ko, but it is only defined if at least one of
CONFIG_KVM_INTEL and CONFIG_KVM_AMD is provided.

Fixes: 590b09b1d88e ("KVM: x86: Register "emergency disable" callbacks when virt is enabled")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 730c2f34d3479676224d0268a5969002798d98d1..f09f13c01c6bbd28fa37fdf50547abf4403658c9 100644 (file)
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -17,8 +17,8 @@ menuconfig VIRTUALIZATION
 
 if VIRTUALIZATION
 
-config KVM
-       tristate "Kernel-based Virtual Machine (KVM) support"
+config KVM_X86
+       def_tristate KVM if KVM_INTEL || KVM_AMD
        depends on X86_LOCAL_APIC
        select KVM_COMMON
        select KVM_GENERIC_MMU_NOTIFIER
@@ -44,7 +44,11 @@ config KVM
        select HAVE_KVM_PM_NOTIFIER if PM
        select KVM_GENERIC_HARDWARE_ENABLING
        select KVM_GENERIC_PRE_FAULT_MEMORY
+       select KVM_GENERIC_PRIVATE_MEM if KVM_SW_PROTECTED_VM
        select KVM_WERROR if WERROR
+
+config KVM
+       tristate "Kernel-based Virtual Machine (KVM) support"
        help
          Support hosting fully virtualized guest machines using hardware
          virtualization extensions.  You will need a fairly recent
@@ -77,7 +81,6 @@ config KVM_SW_PROTECTED_VM
        bool "Enable support for KVM software-protected VMs"
        depends on EXPERT
        depends on KVM && X86_64
-       select KVM_GENERIC_PRIVATE_MEM
        help
          Enable support for KVM software-protected VMs.  Currently, software-
          protected VMs are purely a development and testing vehicle for

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 5494669a055a6e87c2b70b358cc3166d7fa29509..f9dddb8cb46698a15468bfb6e442803edc811021 100644 (file)
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -32,7 +32,7 @@ kvm-intel-y           += vmx/vmx_onhyperv.o vmx/hyperv_evmcs.o
 kvm-amd-y              += svm/svm_onhyperv.o
 endif
 
-obj-$(CONFIG_KVM)      += kvm.o
+obj-$(CONFIG_KVM_X86)  += kvm.o
 obj-$(CONFIG_KVM_INTEL)        += kvm-intel.o
 obj-$(CONFIG_KVM_AMD)  += kvm-amd.o