From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DD9AC5ACD6 for ; Wed, 18 Mar 2020 16:37:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F01B520752 for ; Wed, 18 Mar 2020 16:37:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="N23P3NtM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727183AbgCRQhs (ORCPT ); Wed, 18 Mar 2020 12:37:48 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:54017 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726780AbgCRQhs (ORCPT ); Wed, 18 Mar 2020 12:37:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584549466; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=+UbzLGkfckNn6naER8zwWd5/jxYv9RSpbtDrZv7dGK0=; b=N23P3NtM6TvNWJmUPrdKuHUPmvbb4+das99xq1GRX1ZVDUHAR9cKHOU7vCj5U/8hoLaiXP QQc5APoZ1e3CIXH8kI212SWWZyxTfBdhVS/+3wzbf0K+thcxq9dV+4ZduptqXWGHxkRFxv tSLlzlqGUKS45kGnGk6dF9PnwVHNFdw= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-187-8A2faKy4PR6GLNYA33WyQQ-1; Wed, 18 Mar 2020 12:37:28 -0400 X-MC-Unique: 8A2faKy4PR6GLNYA33WyQQ-1 Received: by mail-wm1-f72.google.com with SMTP id 20so1293744wmk.1 for ; Wed, 18 Mar 2020 09:37:28 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=+UbzLGkfckNn6naER8zwWd5/jxYv9RSpbtDrZv7dGK0=; b=nzG218HzWf6anrKRRMYEPAo+tO2g7MzeOuiYh2E3WpdCW86DxgMw48IG0f8WEVzD6n VmJ0q+nO8R6RLRybiCXuDlQTWj5OdG7XYf1vyT5BVWz7ItRJ3zQpyh6Q0iAf26TIKyiP L7OsICHb8g1ME+GOq4s8W6PmXzvLDYh4DEgyB9a8cZSHAvD/viFpBDuCpm/q7mjoKNDo PSG/d7UwZmV/Ku64CW5sCqZgfTbHB9WGZvObOxV8PlmH9xxeHQvvLuHXe9YCelL670L8 y4IbM2UhvV6SKPEcS7dUPB7UL1kGhCkxVOYuyDdjGxarLSmMsPq1+GEmmZwbyhLSyk95 CwTw== X-Gm-Message-State: ANhLgQ2z+BYZuRz5NSZtzCy5x/hL4ackd9W11of0yXG3X8FP2TvuMB1g 2tSQxw00h5dY9nFsl0MtMGPgip3ApJjrTgqHsDgjBDcFdST5FWd7EJXfZ3l/+ZdtZVQvlarg4F3 PhlMvWT7dPT67JKZ3uCHLE29a X-Received: by 2002:a1c:9658:: with SMTP id y85mr6012856wmd.63.1584549447216; Wed, 18 Mar 2020 09:37:27 -0700 (PDT) X-Google-Smtp-Source: ADFU+vuErvTnZoNeMlI+5nYQs8Cqq5KfLf5VuUoka93mGML+mnpnKCUgo64dYCWUTANi1F5x7RA5fg== X-Received: by 2002:a1c:9658:: with SMTP id y85mr6012823wmd.63.1584549446877; Wed, 18 Mar 2020 09:37:26 -0700 (PDT) Received: from xz-x1.redhat.com ([2607:9880:19c0:32::2]) by smtp.gmail.com with ESMTPSA id i4sm10411120wrm.32.2020.03.18.09.37.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2020 09:37:26 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Michael S . Tsirkin" , Vitaly Kuznetsov , Yan Zhao , peterx@redhat.com, "Dr . David Alan Gilbert" , Christophe de Dinechin , Sean Christopherson , Alex Williamson , Jason Wang , Kevin Tian , Paolo Bonzini Subject: [PATCH v7 00/14] KVM: Dirty ring interface Date: Wed, 18 Mar 2020 12:37:06 -0400 Message-Id: <20200318163720.93929-1-peterx@redhat.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KVM branch: https://github.com/xzpeter/linux/tree/kvm-dirty-ring QEMU branch for testing: https://github.com/xzpeter/qemu/tree/kvm-dirty-ring v7 - rebase to kvm/queue - make as_id an u16 [Sean] - init_rmode_tss: rename idx to i, remove data init to zero [Sean] - update doc for __x86_set_memory_region on ret value after rebase [Sean] - fix sparse warnings for __x86_set_memory_region [syzbot] - test cases [Drew] - use print_skip() - dump log modes without '\b' - support "all" log mode - exit(s/-1/1/) - assert gfns mmap in vcpu_map_dirty_ring - make vcpu_thread/current_vm static For previous versions, please refer to: V1: https://lore.kernel.org/kvm/20191129213505.18472-1-peterx@redhat.com V2: https://lore.kernel.org/kvm/20191221014938.58831-1-peterx@redhat.com V3: https://lore.kernel.org/kvm/20200109145729.32898-1-peterx@redhat.com V4: https://lore.kernel.org/kvm/20200205025105.367213-1-peterx@redhat.com V5: https://lore.kernel.org/kvm/20200304174947.69595-1-peterx@redhat.com V6: https://lore.kernel.org/kvm/20200309214424.330363-1-peterx@redhat.com Overview ============ This is a continued work from Lei Cao and Paolo Bonzini on the KVM dirty ring interface. The new dirty ring interface is another way to collect dirty pages for the virtual machines. It is different from the existing dirty logging interface in a few ways, majorly: - Data format: The dirty data was in a ring format rather than a bitmap format, so dirty bits to sync for dirty logging does not depend on the size of guest memory any more, but speed of dirtying. Also, the dirty ring is per-vcpu, while the dirty bitmap is per-vm. - Data copy: The sync of dirty pages does not need data copy any more, but instead the ring is shared between the userspace and kernel by page sharings (mmap() on vcpu fd) - Interface: Instead of using the old KVM_GET_DIRTY_LOG, KVM_CLEAR_DIRTY_LOG interfaces, the new ring uses the new KVM_RESET_DIRTY_RINGS ioctl when we want to reset the collected dirty pages to protected mode again (works like KVM_CLEAR_DIRTY_LOG, but ring based). To collecting dirty bits, we only need to read the ring data, no ioctl is needed. Ring Layout =========== KVM dirty ring is per-vcpu. Each ring is an array of kvm_dirty_gfn defined as: struct kvm_dirty_gfn { __u32 flags; __u32 slot; /* as_id | slot_id */ __u64 offset; }; Each GFN is a state machine itself. The state is embeded in the flags field, as defined in the uapi header: /* * KVM dirty GFN flags, defined as: * * |---------------+---------------+--------------| * | bit 1 (reset) | bit 0 (dirty) | Status | * |---------------+---------------+--------------| * | 0 | 0 | Invalid GFN | * | 0 | 1 | Dirty GFN | * | 1 | X | GFN to reset | * |---------------+---------------+--------------| * * Lifecycle of a dirty GFN goes like: * * dirtied collected reset * 00 -----------> 01 -------------> 1X -------+ * ^ | * | | * +------------------------------------------+ * * The userspace program is only responsible for the 01->1X state * conversion (to collect dirty bits). Also, it must not skip any * dirty bits so that dirty bits are always collected in sequence. */ Testing ======= This series provided both the implementation of the KVM dirty ring and the test case. Also I've implemented the QEMU counterpart that can run with the new KVM, link can be found at the top of the cover letter. However that's still a very initial version which is prone to change and future optimizations. I did some measurement with the new method with 24G guest running some dirty workload, I don't see any speedup so far, even in some heavy dirty load it'll be slower (e.g., when 800MB/s random dirty rate, kvm dirty ring takes average of ~73s to complete migration while dirty logging only needs average of ~55s). However that's understandable because 24G guest means only 1M dirty bitmap, that's still a suitable case for dirty logging. Meanwhile heavier workload means worst case for dirty ring. More tests are welcomed if there's bigger host/guest, especially on COLO-like workload. Please review, thanks. Peter Xu (14): KVM: X86: Change parameter for fast_page_fault tracepoint KVM: Cache as_id in kvm_memory_slot KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR] KVM: Pass in kvm pointer into mark_page_dirty_in_slot() KVM: X86: Implement ring-based dirty memory tracking KVM: Make dirty ring exclusive to dirty bitmap log KVM: Don't allocate dirty bitmap if dirty ring is enabled KVM: selftests: Always clear dirty bitmap after iteration KVM: selftests: Sync uapi/linux/kvm.h to tools/ KVM: selftests: Use a single binary for dirty/clear log test KVM: selftests: Introduce after_vcpu_run hook for dirty log test KVM: selftests: Add dirty ring buffer test KVM: selftests: Let dirty_log_test async for dirty ring test KVM: selftests: Add "-c" parameter to dirty log test Documentation/virt/kvm/api.rst | 123 +++++ arch/x86/include/asm/kvm_host.h | 6 +- arch/x86/include/uapi/asm/kvm.h | 1 + arch/x86/kvm/Makefile | 3 +- arch/x86/kvm/mmu/mmu.c | 10 +- arch/x86/kvm/mmutrace.h | 9 +- arch/x86/kvm/svm.c | 9 +- arch/x86/kvm/vmx/vmx.c | 89 +-- arch/x86/kvm/x86.c | 50 +- include/linux/kvm_dirty_ring.h | 103 ++++ include/linux/kvm_host.h | 19 + include/trace/events/kvm.h | 78 +++ include/uapi/linux/kvm.h | 53 ++ tools/include/uapi/linux/kvm.h | 99 +++- tools/testing/selftests/kvm/Makefile | 2 - .../selftests/kvm/clear_dirty_log_test.c | 6 - tools/testing/selftests/kvm/dirty_log_test.c | 505 ++++++++++++++++-- .../testing/selftests/kvm/include/kvm_util.h | 4 + tools/testing/selftests/kvm/lib/kvm_util.c | 68 +++ .../selftests/kvm/lib/kvm_util_internal.h | 4 + virt/kvm/dirty_ring.c | 195 +++++++ virt/kvm/kvm_main.c | 162 +++++- 22 files changed, 1460 insertions(+), 138 deletions(-) create mode 100644 include/linux/kvm_dirty_ring.h delete mode 100644 tools/testing/selftests/kvm/clear_dirty_log_test.c create mode 100644 virt/kvm/dirty_ring.c -- 2.24.1