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Fri, 05 Apr 2024 07:58:19 -0400 X-MC-Unique: LvYJznJmMXOAGq3bGEzUmg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 675AB1C05AF2; Fri, 5 Apr 2024 11:58:18 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 20CB240C6CB5; Fri, 5 Apr 2024 11:58:16 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Thomas Bogendoerfer , Nicholas Piggin , Anup Patel , Atish Patra , Sean Christopherson , Andrew Morton , David Hildenbrand , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH 0/4] KVM, mm: remove the .change_pte() MMU notifier and set_pte_at_notify() Date: Fri, 5 Apr 2024 07:58:11 -0400 Message-ID: <20240405115815.3226315-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 87F8A18001C X-Stat-Signature: x4xfjacjhtsw7he85dhgb4tnc53jpm9p X-HE-Tag: 1712318305-796723 X-HE-Meta: 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 4U9ZgfYL Snxx8lffQZUfg/QG47jWb9DQXPdnaIztHwVU9PDF8/8/z2Jt8JRNnEd3LX57A/eI00whN7okcdzU6tb1xJXMVftoYdBt/mg8xjDc3c94KdVZydK6tjtYksKKZ34ahJfgakV8v+u9TBzqqUYnJaY17+DZW2XVv1GBj2yhmY5lLi84XLegHfWYvK8NA202nS/8fMagC 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: List-Subscribe: List-Unsubscribe: The .change_pte() MMU notifier callback was intended as an optimization and for this reason it was initially called without a surrounding mmu_notifier_invalidate_range_{start,end}() pair. It was only ever implemented by KVM (which was also the original user of MMU notifiers) and the rules on when to call set_pte_at_notify() rather than set_pte_at() have always been pretty obscure. It may seem a miracle that it has never caused any hard to trigger bugs, but there's a good reason for that: KVM's implementation has been nonfunctional for a good part of its existence. Already in 2012, commit 6bdb913f0a70 ("mm: wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end", 2012-10-09) changed the .change_pte() callback to occur within an invalidate_range_start/end() pair; and because KVM unmaps the sPTEs during .invalidate_range_start(), .change_pte() has no hope of finding a sPTE to change. Therefore, all the code for .change_pte() can be removed from both KVM and mm/, and set_pte_at_notify() can be replaced with just set_pte_at(). Please review! Also feel free to take the KVM patches through the mm tree, as I don't expect any conflicts. Thanks, Paolo Paolo Bonzini (4): KVM: delete .change_pte MMU notifier callback KVM: remove unused argument of kvm_handle_hva_range() mmu_notifier: remove the .change_pte() callback mm: replace set_pte_at_notify() with just set_pte_at() arch/arm64/kvm/mmu.c | 34 ----------------- arch/loongarch/include/asm/kvm_host.h | 1 - arch/loongarch/kvm/mmu.c | 32 ---------------- arch/mips/kvm/mmu.c | 30 --------------- arch/powerpc/include/asm/kvm_ppc.h | 1 - arch/powerpc/kvm/book3s.c | 5 --- arch/powerpc/kvm/book3s.h | 1 - arch/powerpc/kvm/book3s_64_mmu_hv.c | 12 ------ arch/powerpc/kvm/book3s_hv.c | 1 - arch/powerpc/kvm/book3s_pr.c | 7 ---- arch/powerpc/kvm/e500_mmu_host.c | 6 --- arch/riscv/kvm/mmu.c | 20 ---------- arch/x86/kvm/mmu/mmu.c | 54 +-------------------------- arch/x86/kvm/mmu/spte.c | 16 -------- arch/x86/kvm/mmu/spte.h | 2 - arch/x86/kvm/mmu/tdp_mmu.c | 46 ----------------------- arch/x86/kvm/mmu/tdp_mmu.h | 1 - include/linux/kvm_host.h | 2 - include/linux/mmu_notifier.h | 44 ---------------------- include/trace/events/kvm.h | 15 -------- kernel/events/uprobes.c | 5 +-- mm/ksm.c | 4 +- mm/memory.c | 7 +--- mm/migrate_device.c | 8 +--- mm/mmu_notifier.c | 17 --------- virt/kvm/kvm_main.c | 50 +------------------------ 26 files changed, 10 insertions(+), 411 deletions(-) -- 2.43.0