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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76F13C433EF for ; Tue, 11 Jan 2022 22:12:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346091AbiAKWMx (ORCPT ); Tue, 11 Jan 2022 17:12:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53368 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346058AbiAKWMw (ORCPT ); Tue, 11 Jan 2022 17:12:52 -0500 Received: from mail-ua1-x92a.google.com (mail-ua1-x92a.google.com [IPv6:2607:f8b0:4864:20::92a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D7781C06173F for ; Tue, 11 Jan 2022 14:12:51 -0800 (PST) Received: by mail-ua1-x92a.google.com with SMTP id y4so1334511uad.1 for ; Tue, 11 Jan 2022 14:12:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Nbz7vvk/g5/wyCkKEDLwDSJe+JJYzX4xi71jSjqd8Ds=; b=nxOeeZBxizto3wdZqks3d+GuM/48NtxocfE27Xr6dqtR7ijr6ny0cpE1j8ZUo8irHN FUTPJOvHC2oqzVB7ose2KipHP7/ndid7ROLpw5blVzVqPYSxx3vAUr98tVkavFnbQfUK pLMhQeEVTGVT6MqluFvDbj+Qx3itH7a6DGeqsIJGdPXTD05RBFF0LElrQEUb+lLCSb7o +8H54rhaP8Yy4jJOZyUB9PhmQyFDyOKB1IB9lHvEDFJBWzAUQdb3Sd34x9sXII/2NMP1 NsOYpCd8uTDlBYaIifrXaGwiehi1nnh4P1rSK3cpSoydYYtHYkZ9iGc4A6Kz2yqLIx5q iw9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Nbz7vvk/g5/wyCkKEDLwDSJe+JJYzX4xi71jSjqd8Ds=; b=QhxcCpUGaPN8cX2Cl0ECWc+rbnt64vMVebiuvEvGlPmXoxzEel3TT+Db+/U5KIpRyf i+gvhKGGek8lc4iUqXZke9TQJG1ASF7ZS1oemPffiNJQWDK+45tL8aWFFeapXw7139KY 7UoBsmi2touLIpNBwOkTR+bynch0CwUaMfQwCTodV8UQHApbZdhEO9abZSmqWexbuC2T dwRRhw+W2jR/nVs1Z38a+baAAz7INCGDENMod9s5J6SS0uGHHISba19WA03KGhb1omN7 lBYEEctO/7Lftq245AmaiEvu6/hyoXbeX5hBU3OHXmIv9TrGXJU0wbUC++Ofhx4R+k/d I+pg== X-Gm-Message-State: AOAM533vBZA1rTENsaZNjf5uVp87T4p4KD5sT3hFgrOfFgDWZOZdQMKb 3VGZCvBH9DX55b9FHwMsXHzUnq6aObF+p3VVROI+eg== X-Google-Smtp-Source: ABdhPJzN+ft96CWqj5Q5pNpe5OnVUqYzJeoEqIa+2c9dEmh0mAlkqxKfCPmLLnid4IgaThqckNk6o/WOedpsjDOPsGs= X-Received: by 2002:a05:6102:50a2:: with SMTP id bl34mr1703201vsb.16.1641939170862; Tue, 11 Jan 2022 14:12:50 -0800 (PST) MIME-Version: 1.0 References: <20220110210441.2074798-1-jingzhangos@google.com> <20220110210441.2074798-2-jingzhangos@google.com> <87bl0itvt9.wl-maz@kernel.org> In-Reply-To: <87bl0itvt9.wl-maz@kernel.org> From: Jing Zhang Date: Tue, 11 Jan 2022 14:12:39 -0800 Message-ID: Subject: Re: [RFC PATCH 1/3] KVM: arm64: Use read/write spin lock for MMU protection To: Marc Zyngier Cc: KVM , KVMARM , Will Deacon , Paolo Bonzini , David Matlack , Oliver Upton , Reiji Watanabe Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Jan 11, 2022 at 2:23 AM Marc Zyngier wrote: > > On Mon, 10 Jan 2022 21:04:39 +0000, > Jing Zhang wrote: > > > > To reduce the contentions caused by MMU lock, some MMU operations can > > be performed under read lock. > > One improvement is to add a fast path for permission relaxation during > > dirty logging under the read lock. > > This commit message really doesn't say what this patch does > (converting our MMU spinlock to a rwlock, and replacing all instances > of the lock being acquired with a write lock acquisition). Crucially, > it only mention the read lock which appears *nowhere* in this patch. > Good point. Will use the below message instead for future posts. "Replace MMU spinlock with rwlock and update all instances of the lock being acquired with a write lock acquisition. Future commit will add a fast path for permission relaxation during dirty logging under a read lock." > Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible. Thanks, Jing