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: 13618948 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 85AEA16C6A6 for ; Fri, 5 Apr 2024 11:58:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712318306; cv=none; b=inoJsfP9R0khnPMtXaYmo2ac78KCY79e7eWcMcCxQ8+hUF/z4p9oSWkVm6aSt66dGwwgGle7ltd1ie2Yt78nxwTsFR4wDttojLDflwyo8aMFqjorC7nbHajaCioaci1L9npUVt51jE5ToljSZ+TcCfeIaPwqBvYrMcx7jJfm9pg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712318306; c=relaxed/simple; bh=2JWd/jbsS4JWnaAnGX+DxvfAkF7VrJqaJ4JcNlZZdG8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=CNXtaIH1mxC1IQLQHTTe2czdZjydlBuVZzAQIcwkUUJavZMujg+TK/0enCpBkUuh8TRAgQ59uM1eft4JXArEKabFBt/5/EPdNh2UA/K4AOOvmZ2DDXliLTyt8T7wqUKxgBA1xi0MHTOKtoNmdxFBiP1BgrJ/TXQdTjc7MAblrIs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=NgVXLLhz; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NgVXLLhz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712318303; 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=NgVXLLhzna25f7mPE4xKhwLXbltaeb0eLy9gCjQPifQ9Ia51efC3MiMEkpqG+chPd4h928 +O0vbiMD+NJpCZG8sIdt50f21d3LmDBsx1X5mXqaC8a370iHQZMhQePtwNE/sVrtUvTsNH KX02rcm249Qg1vD7by0wsg45w3qCXXk= 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> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 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