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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 E49DEC433DF for ; Tue, 16 Jun 2020 09:37:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B99662074D for ; Tue, 16 Jun 2020 09:37:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728592AbgFPJhD (ORCPT ); Tue, 16 Jun 2020 05:37:03 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:6266 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728335AbgFPJgV (ORCPT ); Tue, 16 Jun 2020 05:36:21 -0400 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id DC5347673396AED17823; Tue, 16 Jun 2020 17:36:18 +0800 (CST) Received: from DESKTOP-5IS4806.china.huawei.com (10.173.221.230) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.487.0; Tue, 16 Jun 2020 17:36:10 +0800 From: Keqian Zhu To: , , , CC: Catalin Marinas , Marc Zyngier , James Morse , Will Deacon , "Suzuki K Poulose" , Sean Christopherson , Julien Thierry , Mark Brown , "Thomas Gleixner" , Andrew Morton , Alexios Zavras , , , , Keqian Zhu Subject: [PATCH 08/12] KVM: Omit dirty log sync in log clear if initially all set Date: Tue, 16 Jun 2020 17:35:49 +0800 Message-ID: <20200616093553.27512-9-zhukeqian1@huawei.com> X-Mailer: git-send-email 2.8.4.windows.1 In-Reply-To: <20200616093553.27512-1-zhukeqian1@huawei.com> References: <20200616093553.27512-1-zhukeqian1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.173.221.230] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Synchronizing dirty log during log clear is useful only when the dirty bitmap of userspace contains dirty bits that memslot dirty bitmap does not contain, because we can sync new dirty bits to memslot dirty bitmap, then we can clear them by the way and avoid reporting them to userspace later. With dirty bitmap "initially all set" feature, the above situation will not appear if userspace logic is normal, so we can omit dirty log sync in log clear. This is valuable when dirty log sync is a high-cost operation, such as arm64 DBM. Signed-off-by: Keqian Zhu --- virt/kvm/kvm_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3722343fd460..6c147d6f9da6 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1554,7 +1554,8 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, (log->num_pages < memslot->npages - log->first_page && (log->num_pages & 63))) return -EINVAL; - kvm_arch_sync_dirty_log(kvm, memslot); + if (!kvm_dirty_log_manual_protect_and_init_set(kvm)) + kvm_arch_sync_dirty_log(kvm, memslot); flush = false; dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot); -- 2.19.1