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 13EEAC433F5 for ; Wed, 27 Apr 2022 01:16:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356604AbiD0BTs (ORCPT ); Tue, 26 Apr 2022 21:19:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344391AbiD0BTr (ORCPT ); Tue, 26 Apr 2022 21:19:47 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C06B2E08C for ; Tue, 26 Apr 2022 18:16:38 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id n33-20020a17090a5aa400b001d28f5ee3f9so481159pji.4 for ; Tue, 26 Apr 2022 18:16:38 -0700 (PDT) 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=6jFJtCmRVi276uO+VGW/oZwgeFrr/SjrfPgb9kCh74I=; b=Ejd4R30p2LtyMa6p1euHblC5a1PVQG8JIbo3FgFvBREIipq68XnWsPcVw3rbNVlVRa CYj87Ri/LwP/YWntee2iUJqvqxwWFM3jAusTkeJfiv8yq9O8OvyGsQgrTL1UTj05O+km YacRIRrHQGJ+covG3L+RjDcC0IcLAAm0+KNZh2/AQ5bDgpj9Inpi9my7dWTK3D3NjLFC Xw7p+j7POZgPmFxHPIO0N/CnNquhCXal967FLD6DN355ExH/wgFEaziKN8XZCjlKTESm X7zL532ggJvHsq5PEf+o9o5LDBz2JSjOcZrYR1bcVR2VzLSGPRkQXIm5pk4pF5ubp6Nn hycQ== 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=6jFJtCmRVi276uO+VGW/oZwgeFrr/SjrfPgb9kCh74I=; b=vjw17d6IN4ZetBp5Rl68bghMWLVC3+tp/LT9LakAvjZoBJBAHitL+zydtxyZaVDD6i EZ31u9vBsjCgKeuQhRt8G/p6um/hclaerCyh48h3WKrbGpEZq4Y3FVXAjbcJJTtJAhVQ kXHdu+KoKdsXgHHSnbemYisNf5r/9v1vf2QbFbyd+ZXE/MK9Ws9Dyri2mw5en494Q3aG 4QqPqHtN0mI+LfLgpYsiBU1U8HMyPHihT0xhWug+d8zWTS81TG94aQqDezBFOQpKPPoW wcuCbuyCitpRgPS2LldiWh8Kixd0WnHvise9jDLnRQgFnbtUJVwixZMzCTcreUf6MNsD iU3Q== X-Gm-Message-State: AOAM530i1xtrnvSv35TWZyzoJObos5gh7BvQ/wxeFwO1nZHq/wh7X9XV 3I49JFu4tVW+77MM55OZ6haglw== X-Google-Smtp-Source: ABdhPJyJeG+jCHswMiFsLr+KMoQRT+wuqnbu0rLT1G337/GLjVem5pDjXGgenb11IZ0toAkWne8LxA== X-Received: by 2002:a17:90a:d3d1:b0:1bb:fdc5:182 with SMTP id d17-20020a17090ad3d100b001bbfdc50182mr41137810pjw.206.1651022197458; Tue, 26 Apr 2022 18:16:37 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id n4-20020a637204000000b00398522203a2sm14599905pgc.80.2022.04.26.18.16.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Apr 2022 18:16:36 -0700 (PDT) Date: Wed, 27 Apr 2022 01:16:33 +0000 From: Sean Christopherson To: Mingwei Zhang Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm , LKML , Ben Gardon , David Matlack Subject: Re: [PATCH] KVM: x86/mmu: add lockdep check before lookup_address_in_mm() Message-ID: References: <20220327205803.739336-1-mizhang@google.com> <7597fe2c-ce04-0e21-bd6c-4051d7d5101d@redhat.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 Tue, Apr 26, 2022, Mingwei Zhang wrote: > > I completely agree that lookup_address() and friends are unnecessarily fragile, > > but I think that attempting to harden them to fix this KVM bug will open a can > > of worms and end up delaying getting KVM fixed. > > So basically, we need to: > - choose perf_get_page_size() instead of using any of the > lookup_address*() in mm. > - add a wrapper layer to adapt: 1) irq disabling/enabling and 2) size > -> level translation. > > Agree? Drat, I didn't see that it returns the page size, not the level. That's a bit unfortunate. It definitely makes me less averse to fixing lookup_address_in_pgd() Hrm. I guess since we know there's at least one broken user, and in theory fixing lookup_address_in_pgd() should do no harm to users that don't need protection, it makes sense to just fix lookup_address_in_pgd() and see if the x86 maintainers push back.