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Wed, 29 May 2024 14:55:47 -0700 (PDT) Date: Wed, 29 May 2024 14:55:46 -0700 In-Reply-To: <20240529180510.2295118-5-jthoughton@google.com> Mime-Version: 1.0 References: <20240529180510.2295118-1-jthoughton@google.com> <20240529180510.2295118-5-jthoughton@google.com> Message-ID: Subject: Re: [PATCH v4 4/7] KVM: Move MMU lock acquisition for test/clear_young to architecture From: Sean Christopherson To: James Houghton Cc: Andrew Morton , Paolo Bonzini , Albert Ou , Ankit Agrawal , Anup Patel , Atish Patra , Axel Rasmussen , Bibo Mao , Catalin Marinas , David Matlack , David Rientjes , Huacai Chen , James Morse , Jonathan Corbet , Marc Zyngier , Michael Ellerman , Nicholas Piggin , Oliver Upton , Palmer Dabbelt , Paul Walmsley , Raghavendra Rao Ananta , Ryan Roberts , Shaoqin Huang , Shuah Khan , Suzuki K Poulose , Tianrui Zhao , Will Deacon , Yu Zhao , Zenghui Yu , kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240529_145552_602484_73C30357 X-CRM114-Status: GOOD ( 11.17 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 29, 2024, James Houghton wrote: > For implementation mmu_notifier_{test,clear}_young, the KVM memslot > walker used to take the MMU lock for us. Now make the architectures > take it themselves. Hmm, *forcing* architectures to take mmu_lock is a step backwards. Rather than add all of this churn, what about adding CONFIG_KVM_MMU_NOTIFIER_LOCKLESS, e.g. static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn, unsigned long start, unsigned long end, gfn_handler_t handler) { struct kvm *kvm = mmu_notifier_to_kvm(mn); const struct kvm_mmu_notifier_range range = { .start = start, .end = end, .handler = handler, .on_lock = (void *)kvm_null_fn, .flush_on_ret = false, .may_block = false, .lockless = IS_ENABLED(CONFIG_KVM_MMU_NOTIFIER_LOCKLESS), }; return __kvm_handle_hva_range(kvm, &range).ret; } _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel