On 15/01/21 10:45, Peter Zijlstra wrote:

On Thu, Jan 14, 2021 at 10:27:56PM -0500, Jason Baron wrote:

quoted

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 5060922..9d4492b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h

@@ -1350,7 +1350,7 @@ void kvm_arch_free_vm(struct kvm *kvm);
  static inline int kvm_arch_flush_remote_tlb(struct kvm *kvm)
  {
  	if (kvm_x86_ops.tlb_remote_flush &&
-	    !kvm_x86_ops.tlb_remote_flush(kvm))
+	    !static_call(kvm_x86_tlb_remote_flush)(kvm))
  		return 0;
  	else
  		return -ENOTSUPP;

Would you be able to use something like this?

   https://lkml.kernel.org/r/20201110101307.GO2651@hirez.programming.kicks-ass.net

we could also add __static_call_return1(), if that would help.

I think I'd rather make the default callee return -ENOTSUPP directly and 
remove the "if" completely.  So __static_call_return1() is not 
particularly useful here.

Paolo