From patchwork Fri Apr 5 11:58:11 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13618959 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 61B52C67861 for ; Fri, 5 Apr 2024 11:58:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=zNXCyxIUgDeja5D8XCVQj8t6Jczmrv9y0NJWRau/XKk=; b=4gHyJgZA/aicGD bR3TPzdyBmclOfi2utgddSLfaxuQrUSlRsFSa+61wlSShV6reDcnmlJYuv+Vauqi5rBH3VpSWFfO2 i5ImcMuK2jF5b9aadT7Oul09Fa1kJA7GojtZH/zwHAq93eqPOwtn8DfxQxPTj6gTyunMfDPFGHbjk nLCa4A8RQEZtNEnV6/kfNy448QhDNQ66IwvyZlTkgpC8RVXRAs1uzQpmDYOdFnCNfKF1xOEB7SnUO 9uaOlaQh0f1imetTpmpSqQwfQAt7GZy3N0GdQZ3PfZM6LVi0OOhioCmF6H70iYCLtde6naCoq26dg SBXIMhMJSSjl+0MpQDpA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsiDE-00000006mNW-2pEN; Fri, 05 Apr 2024 11:58:28 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsiDB-00000006mKt-1eYq for linux-arm-kernel@lists.infradead.org; Fri, 05 Apr 2024 11:58:27 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712318304; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=W+x0+CoZa6QVpu1rtgd+fH2pAb0xlu8sJLIuEb6A4kU=; b=UF8NNnVzDf/DQIBknZnHp0hw1idQ4fgvBp96CrPquMIa30b2eepda8I+08PWwzRVs8szYi 0QHlBqr024GiHJWAOtBErRW+J2qPZ/hxlb95EA+FXJrK3mq/8UQt7lB17w70aRvBO+KIZu mDtXOC9US4jYuhC9Ax1VU0MYiCN8rA0= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-589-LvYJznJmMXOAGq3bGEzUmg-1; 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 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240405_045825_544808_E907EC1E X-CRM114-Status: GOOD ( 12.47 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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(-) Reviewed-by: Marc Zyngier