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Date:   Fri, 15 Jan 2021 10:26:51 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Jason Baron <jbaron@akamai.com>
Cc:     pbonzini@redhat.com, seanjc@google.com, kvm@vger.kernel.org,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH v2 2/3] KVM: x86: introduce definitions to support static
 calls for kvm_x86_ops
Message-ID: <YAFf2+nvhvWjGImy@hirez.programming.kicks-ass.net>
References: <cover.1610680941.git.jbaron@akamai.com>
 <e5cc82ead7ab37b2dceb0837a514f3f8bea4f8d1.1610680941.git.jbaron@akamai.com>
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On Thu, Jan 14, 2021 at 10:27:55PM -0500, Jason Baron wrote:
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3f7c1fc..c21927f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -113,6 +113,15 @@ static int sync_regs(struct kvm_vcpu *vcpu);
>  struct kvm_x86_ops kvm_x86_ops __read_mostly;
>  EXPORT_SYMBOL_GPL(kvm_x86_ops);
>  
> +#define KVM_X86_OP(func)					     \
> +	DEFINE_STATIC_CALL_NULL(kvm_x86_##func,			     \
> +				*(((struct kvm_x86_ops *)0)->func));
> +#define KVM_X86_OP_NULL KVM_X86_OP
> +#include <asm/kvm-x86-ops.h>
> +EXPORT_STATIC_CALL_GPL(kvm_x86_get_cs_db_l_bits);
> +EXPORT_STATIC_CALL_GPL(kvm_x86_cache_reg);
> +EXPORT_STATIC_CALL_GPL(kvm_x86_tlb_flush_current);

Would something like:

  https://lkml.kernel.org/r/20201110103909.GD2594@hirez.programming.kicks-ass.net

Be useful? That way modules can call the static_call() but not change
it.