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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id h21sm6580708pfc.118.2021.09.17.09.53.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Sep 2021 09:53:56 -0700 (PDT) Date: Fri, 17 Sep 2021 16:53:52 +0000 From: Sean Christopherson To: Peter Zijlstra Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Will Deacon , Mark Rutland , Catalin Marinas , Marc Zyngier , Guo Ren , Nick Hu , Greentime Hu , Vincent Chen , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, Paolo Bonzini , Boris Ostrovsky , Juergen Gross , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Morse , Alexandru Elisei , Suzuki K Poulose , "H. Peter Anvin" , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Stefano Stabellini , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, Artem Kashkanov , Like Xu , Zhu Lingshan Subject: Re: [PATCH v2 00/13] perf: KVM: Fix, optimize, and clean up callbacks Message-ID: References: <20210828003558.713983-1-seanjc@google.com> <20210828201336.GD4353@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Fri, Sep 17, 2021, Peter Zijlstra wrote: > On Thu, Sep 16, 2021 at 09:37:43PM +0000, Sean Christopherson wrote: > So I don't mind exporting __static_call_return0, but exporting a raw > static_call is much like exporting a function pointer :/ Ya, that part is quite gross. > > The unregister path would also need its own synchronize_rcu(). In general, I > > don't love duplicating the logic, but it's not the end of the world. > > > > Either way works for me. Paolo or Peter, do either of you have a preference? > > Can we de-feature kvm as a module and only have this PT functionality > when built-in? :-) I agree that many of the for-KVM exports are ugly, especially several of the perf exports, but I will fight tooth and nail to keep KVM-as-a-module. It is invaluable for development and testing, and in the not-too-distant future there is KVM-maintenance related functionality that we'd like to implement that relies on KVM being a module. I would be more than happy to help explore approaches that reduce the for-KVM exports, but I am strongly opposed to defeaturing KVM-as-a-module. I have a few nascent ideas for eliminating a handful of a random exports, but no clever ideas for eliminating perf's for-KVM exports.