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 5D1CDC433EF for ; Mon, 22 Nov 2021 19:57:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240358AbhKVUAj (ORCPT ); Mon, 22 Nov 2021 15:00:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239711AbhKVUAi (ORCPT ); Mon, 22 Nov 2021 15:00:38 -0500 Received: from mail-io1-xd34.google.com (mail-io1-xd34.google.com [IPv6:2607:f8b0:4864:20::d34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3125DC061574 for ; Mon, 22 Nov 2021 11:57:31 -0800 (PST) Received: by mail-io1-xd34.google.com with SMTP id e144so24905422iof.3 for ; Mon, 22 Nov 2021 11:57:31 -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=Tu3lxcIg7V05BfeRU1lfgCDNUx8anDFHSWBxng5Jwac=; b=srhMB9M6hX0PkCDJD/JQkumC/IQ8M7Lz+cplUXYaHfAi76HHbwUnWECul4L4RyW3GZ w1ashi5ZD6M2Std6cYhwV68h2Oek1z9hhwcbYqJduTemt9RX7vRtMkAIX4Scg3jiWfJ6 L19cXhw/DAa7JB41HMYsjsNBKGjjunmogVFekOu8oi2kg5RyRi0p1jCrYKRfOUPVsA5l ViZNpsmbYOPVjM5hEek05EhquFS15s4A8GxJYDNhVixHuFAk3Fbk4J/rMjFqaYxYEqnv N7NFJ+2Z1p0OW9A9GFli/pvYeLEjO9UQbwIsCNSOru8/ZDz25V2MSfmjXudcVOxTxc+E khYg== 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=Tu3lxcIg7V05BfeRU1lfgCDNUx8anDFHSWBxng5Jwac=; b=D5637sc4sXQKl4jNYMA4hTJlJjJquDV4Q/+t+lhxwJcLCxD8XHIw04bjLtlmOuoG3K uwxdLmzJ9Fm2JVUCreMGHOZ5xtPglMUHXaxAUZeYtc6fdgF4VUMtijZJn2MQgJt7+Lmw qFFfCGKfwCTFKz6A8S1+Upj0oFnpWGsvy5glygeqtawhP9L9e5MhPf2YBMzzi1Wi77+b ATyoUu5jzHlxzGTNKvdvsveFsMBcRqxzMhOpYgtjVSpkfMdTjdLk3ftQvkdPFJnMooYW 7hAzbdSPzh5be5ox+1qNv48PHp/8TybmvlizqiU8uf0w7WnxK7/9gneeJMJ2uc1mHItr Kivg== X-Gm-Message-State: AOAM531v0VB83GZ4yEpNclYmtH6kdLaY9B7aAaWRdzyyg7EKceh7UZjY byaZyKd9nP9hIlqX/gw4ycZlQ1J8ePp9ivfxtA/jmg== X-Google-Smtp-Source: ABdhPJyHs56CGDl8ro/bvC8wCPGXjqMFzrf4zkecyaHKTPWrCYSJk7Xl8Ol3tNmm5cWwTHdBhkyJ1bFqwou2YOv2q/4= X-Received: by 2002:a5d:9493:: with SMTP id v19mr24296286ioj.34.1637611050436; Mon, 22 Nov 2021 11:57:30 -0800 (PST) MIME-Version: 1.0 References: <20211120045046.3940942-1-seanjc@google.com> <20211120045046.3940942-6-seanjc@google.com> In-Reply-To: <20211120045046.3940942-6-seanjc@google.com> From: Ben Gardon Date: Mon, 22 Nov 2021 11:57:19 -0800 Message-ID: Subject: Re: [PATCH 05/28] KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP MMU To: Sean Christopherson Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hou Wenlong Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, Nov 19, 2021 at 8:51 PM Sean Christopherson wrote: > > Explicitly check for preset SPTEs when clearing dirty bits in the TDP > MMU. This isn't strictly required for correctness, as setting the dirty > bit in a defunct SPTE will not change the SPTE from !PRESENT to PRESENT. > However, the guarded MMU_WARN_ON() in spte_ad_need_write_protect() would > complain if anyone actually turned on KVM's MMU debugging. > > Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU") > Cc: Ben Gardon > Signed-off-by: Sean Christopherson Reviewed-by: Ben Gardon > --- > arch/x86/kvm/mmu/tdp_mmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 1db8496259ad..c575df121b19 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -1246,6 +1246,9 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, > if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) > continue; > > + if (!is_shadow_present_pte(iter.old_spte)) > + continue; > + > if (spte_ad_need_write_protect(iter.old_spte)) { > if (is_writable_pte(iter.old_spte)) > new_spte = iter.old_spte & ~PT_WRITABLE_MASK; > -- > 2.34.0.rc2.393.gf8c9666880-goog >