Re: [PATCH v10 08/12] kvm: Define EXPORT_STATIC_CALL_FOR_KVM()

[Sean Christopherson <seanjc@google.com>]

On Tue, Apr 14, 2026, Pawan Gupta wrote:
> 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 the
> 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.
> 
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> ---
>  arch/x86/include/asm/kvm_types.h |  1 +
>  include/linux/kvm_types.h        | 13 ++++++++++++-
>  2 files changed, 13 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..c81f4fdba625 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)
>  /*
> @@ -27,7 +29,16 @@
>  #define EXPORT_SYMBOL_FOR_KVM(symbol)
>  #endif /* IS_MODULE(CONFIG_KVM) */
>  #endif /* EXPORT_SYMBOL_FOR_KVM */
> -#endif
> +
> +#ifndef EXPORT_STATIC_CALL_FOR_KVM
> +#if IS_MODULE(CONFIG_KVM)
> +#define EXPORT_STATIC_CALL_FOR_KVM(symbol) EXPORT_STATIC_CALL_FOR_MODULES(symbol, "kvm")
> +#else
> +#define EXPORT_STATIC_CALL_FOR_KVM(symbol)
> +#endif /* IS_MODULE(CONFIG_KVM) */
> +#endif /* EXPORT_STATIC_CALL_FOR_KVM */
> +
> +#endif /* KVM_SUB_MODULES */

I think I'd prefer to require EXPORT_SYMBOL_FOR_KVM and EXPORT_STATIC_CALL_FOR_KVM
to come as a pair from arch code.  I can't think of a scenario where arch code
should override one but not the other.  The end result is slightly less ugly :-)

---
 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) */
+#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
+#endif /* KVM_SUB_MODULES */
 
 #ifndef __ASSEMBLER__
 

base-commit: 56b7ace84970ff647b095849e80bc36c094760aa
--