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Wed, 24 May 2023 14:39:52 -0700 (PDT) Date: Wed, 24 May 2023 14:39:50 -0700 In-Reply-To: <20230524203336.GC3447678@hirez.programming.kicks-ass.net> Mime-Version: 1.0 References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220706082016.2603916-9-chao.p.peng@linux.intel.com> <20230524203336.GC3447678@hirez.programming.kicks-ass.net> Message-ID: Subject: Re: [PATCH v7 08/14] KVM: Rename mmu_notifier_* From: Sean Christopherson To: Peter Zijlstra Cc: Kautuk Consul , Chao Peng , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, linux-kselftest@vger.kernel.org, Paolo Bonzini , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Shuah Khan , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, Muchun Song Content-Type: text/plain; charset="us-ascii" X-Rspam-User: X-Stat-Signature: 1zowdrcfsnukzxs5rfm5amsndte37btd X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2586B20018 X-HE-Tag: 1684964392-476122 X-HE-Meta: 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 bwm5shMN 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, May 24, 2023, Peter Zijlstra wrote: > On Wed, May 24, 2023 at 01:16:03PM -0700, Sean Christopherson wrote: > > Of course, the only accesses outside of mmu_lock are reads, so on x86 that > > "atomic" access is just a READ_ONCE() load, but that's not the case for all > > architectures. > > This is true on *all* archs. atomic_set() and atomic_read() are no more > and no less than WRITE_ONCE() / READ_ONCE(). Ah, I take it s390's handcoded assembly routines are just a paranoid equivalents and not truly special? "l" and "st" do sound quite generic... commit 7657e41a0bd16c9d8b3cefe8fd5d6ac3c25ae4bf Author: Heiko Carstens Date: Thu Feb 17 13:13:58 2011 +0100 [S390] atomic: use inline asm Use inline assemblies for atomic_read/set(). This way there shouldn't be any questions or subtle volatile semantics left. static inline int __atomic_read(const atomic_t *v) { int c; asm volatile( " l %0,%1\n" : "=d" (c) : "R" (v->counter)); return c; } static inline void __atomic_set(atomic_t *v, int i) { asm volatile( " st %1,%0\n" : "=R" (v->counter) : "d" (i)); }