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 49822C433EF for ; Mon, 22 Nov 2021 20:20:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240443AbhKVUXF (ORCPT ); Mon, 22 Nov 2021 15:23:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232880AbhKVUXD (ORCPT ); Mon, 22 Nov 2021 15:23:03 -0500 Received: from mail-pj1-x1034.google.com (mail-pj1-x1034.google.com [IPv6:2607:f8b0:4864:20::1034]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4956C061574 for ; Mon, 22 Nov 2021 12:19:56 -0800 (PST) Received: by mail-pj1-x1034.google.com with SMTP id gf14-20020a17090ac7ce00b001a7a2a0b5c3so189374pjb.5 for ; Mon, 22 Nov 2021 12:19:56 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=mRxIeU9HPgzOY3clEU+77o23b2EAQbNCRiTPpgLxklA=; b=CKa8JazZ41nRBv/+ULd1g5vvoetmCxEd7/52ZApQmKaWjCkKzv4wX0aZcynTwBG44V dp/yPAisfCYmXCGEtl96K9Dvesy2q4l76JsT5rxcVJ3epWACmiFg4Y8YRJ7LDZwlx/Ic u3BtM8hd9e6keFl2lJWiRpXc5BGJn+kdyr0DJdBYkWuZXPogLKvJD4IRHVqHWo9IrGL4 XsgNrdtYF8TrbjEOgbpuWGcnsOYJUAjwz5z5qtv7l6WS04Ik89Ksmbg6auAPVWTPxVm5 uY1LjtFCsW/4IN1RbSbExW3o2r2XKCw/7R4tRrmrNqAra2UQjds5J0CuGupE1lPTaEQH YZag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=mRxIeU9HPgzOY3clEU+77o23b2EAQbNCRiTPpgLxklA=; b=3jgq1gY/37T+9g/MwqQnpMuzDtCfM6rTuVCXiO/iH87EW5vbWKlfefvOOl8LpX6wPy qBjnVClt+zP96lBGn8hf6IJz+9DKUKNBsTNkUPEGC8FZJHtymQi+Is8N1ln5niAAFm/4 c/jRVuZSSQUgS+ETTJFYMCxBNMNam/nKk5gCfQ/NBsP11MMAS9oAzjlznv+R3kBIAxWT VZBa3MxdyI0w3ZJNayDdNwG8ivbYiu5y1jgFCR/kblC8xrM8A/PYeXp5C1FJwisClE4S FiTaqKJvYeIwgzsGwtfVRZBDi5KzwjFVKYQXx/yzlct14Rg7G7kVI0k7qCi6w6P0RxGT 2haQ== X-Gm-Message-State: AOAM532DD3UxJIOikCIw8oCE5IZJinMQCjup+RFqBsAlMt+/0Mv46pr0 CSwtexpVqYwj6+TQrZ+Isr//AA== X-Google-Smtp-Source: ABdhPJzQAX5rio7DTTwz9eNYQ6QSDxHgCK5fgM6VOwMLfwtHzlnXhLRnQp6cNfcC09xIgx8XvJICDQ== X-Received: by 2002:a17:902:d4d0:b0:141:c13d:6c20 with SMTP id o16-20020a170902d4d000b00141c13d6c20mr112062554plg.44.1637612396182; Mon, 22 Nov 2021 12:19:56 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id v38sm6717082pgl.38.2021.11.22.12.19.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Nov 2021 12:19:55 -0800 (PST) Date: Mon, 22 Nov 2021 20:19:52 +0000 From: Sean Christopherson To: Ben Gardon Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hou Wenlong Subject: Re: [PATCH 09/28] KVM: x86/mmu: Require mmu_lock be held for write in unyielding root iter Message-ID: References: <20211120045046.3940942-1-seanjc@google.com> <20211120045046.3940942-10-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 22, 2021, Ben Gardon wrote: > > + * Holding mmu_lock for write obviates the need for RCU protection as the list > > + * is guaranteed to be stable. > > + */ > > +#define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ > > + list_for_each_entry(_root, &_kvm->arch.tdp_mmu_roots, link) \ > > if (kvm_mmu_page_as_id(_root) != _as_id) { \ > > + lockdep_assert_held_write(&(_kvm)->mmu_lock); \ > > Did you mean for this lockdep to only be hit in this uncommon > non-matching ASID case? Yes and no. Yes, I intended what I wrote. No, this isn't intended to be limited to a memslot address space mismatch, but at the time I wrote this I was apparently lazy or inept :-) In hindsight, this would be better: /* blah blah blah */ static inline struct list_head *kvm_get_tdp_mmu_roots_exclusive(struct kvm *kvm) { lockdep_assert_held_write(&kvm->mmu_lock); return &kvm->arch.tdp_mmu_roots; } #define for_each_tdp_mmu_root(_kvm, _root, _as_id) \ list_for_each_entry(_root, kvm_get_tdp_mmu_roots_exclusive(kvm), link) \ if (kvm_mmu_page_as_id(_root) != _as_id) { \ } else