[PATCH v11 08/12] kvm: Define EXPORT_STATIC_CALL_FOR_KVM()

[Pawan Gupta]

EXPORT_SYMBOL_FOR_KVM() exists to export symbols to KVM modules. Static
calls need the same treatment when the core kernel defines a static_call
that KVM needs access to (e.g. from a VM-exit path).

Define EXPORT_STATIC_CALL_FOR_KVM() as the static_call analogue of
EXPORT_SYMBOL_FOR_KVM(). The same three-way logic applies:

  - KVM_SUB_MODULES defined: export to "kvm," plus all sub-modules
  - KVM=m, no sub-modules: export to "kvm" only
  - KVM built-in: no export needed (noop)

  As with EXPORT_SYMBOL_FOR_KVM(), allow architectures to override both
  macros (e.g. to suppress the export when kvm.ko itself will not be
  built despite CONFIG_KVM=m). Add the x86 no-op overrides in
  arch/x86/include/asm/kvm_types.h for that case. To keep the pair in
  sync, EXPORT_STATIC_CALL_FOR_KVM() is defined inside the
  EXPORT_SYMBOL_FOR_KVM #ifndef block; an arch that defines
  EXPORT_SYMBOL_FOR_KVM must also define EXPORT_STATIC_CALL_FOR_KVM or the
  build will fail with a compile-time error.

As with EXPORT_SYMBOL_FOR_KVM(), allow architectures to override
EXPORT_STATIC_CALL_FOR_KVM definition (e.g. to suppress the export when
kvm.ko itself will not be built despite CONFIG_KVM=m). Add the x86 no-op
override in arch/x86/include/asm/kvm_types.h for that case.

Architectures must also define EXPORT_STATIC_CALL_FOR_KVM when they define
EXPORT_SYMBOL_FOR_KVM.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/kvm_types.h |  1 +
 include/linux/kvm_types.h        | 10 +++++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_types.h b/arch/x86/include/asm/kvm_types.h
index d7c704ed1be9..bceeaed2940e 100644
--- a/arch/x86/include/asm/kvm_types.h
+++ b/arch/x86/include/asm/kvm_types.h
@@ -15,6 +15,7 @@
  * at least one vendor module is enabled.
  */
 #define EXPORT_SYMBOL_FOR_KVM(symbol)
+#define EXPORT_STATIC_CALL_FOR_KVM(symbol)
 #endif
 
 #define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE 40
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index a568d8e6f4e8..be602d3f287e 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -13,6 +13,8 @@
 	EXPORT_SYMBOL_FOR_MODULES(symbol, __stringify(KVM_SUB_MODULES))
 #define EXPORT_SYMBOL_FOR_KVM(symbol) \
 	EXPORT_SYMBOL_FOR_MODULES(symbol, "kvm," __stringify(KVM_SUB_MODULES))
+#define EXPORT_STATIC_CALL_FOR_KVM(symbol) \
+	EXPORT_STATIC_CALL_FOR_MODULES(symbol, "kvm," __stringify(KVM_SUB_MODULES))
 #else
 #define EXPORT_SYMBOL_FOR_KVM_INTERNAL(symbol)
 /*
@@ -23,11 +25,17 @@
 #ifndef EXPORT_SYMBOL_FOR_KVM
 #if IS_MODULE(CONFIG_KVM)
 #define EXPORT_SYMBOL_FOR_KVM(symbol) EXPORT_SYMBOL_FOR_MODULES(symbol, "kvm")
+#define EXPORT_STATIC_CALL_FOR_KVM(symbol) EXPORT_STATIC_CALL_FOR_MODULES(symbol, "kvm")
 #else
 #define EXPORT_SYMBOL_FOR_KVM(symbol)
+#define EXPORT_STATIC_CALL_FOR_KVM(symbol)
 #endif /* IS_MODULE(CONFIG_KVM) */
-#endif /* EXPORT_SYMBOL_FOR_KVM */
+#else
+#ifndef EXPORT_STATIC_CALL_FOR_KVM
+#error Must #define EXPORT_STATIC_CALL_FOR_KVM if #defining EXPORT_SYMBOL_FOR_KVM
 #endif
+#endif /* EXPORT_SYMBOL_FOR_KVM */
+#endif /* KVM_SUB_MODULES */
 
 #ifndef __ASSEMBLER__
 

-- 
2.34.1