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 9B1B2C433F5 for ; Tue, 26 Apr 2022 17:51:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231793AbiDZRy4 (ORCPT ); Tue, 26 Apr 2022 13:54:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34712 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353846AbiDZRwc (ORCPT ); Tue, 26 Apr 2022 13:52:32 -0400 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40DFA189282; Tue, 26 Apr 2022 10:49:23 -0700 (PDT) Received: by mail-wm1-x335.google.com with SMTP id m22-20020a05600c3b1600b00393ed50777aso2060804wms.3; Tue, 26 Apr 2022 10:49:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=GRjbKlr19Mn5FxSswFnS14l/zAFp26BdYRhHkX31QzQ=; b=SwTUcIrS5vPJhHyu9bW1ZNIP4QBQ44Kyj4iNx6wCNlsTlrQSWgKqT9QFTUvYG/JdFc QSJO7F1tUpiBtEsf9hnDYJbjv/c84yq1TrQybx0CvMl0nHW8+TzLZyoEtRWBnhSTYXPZ tkXGhd8xjfk8+vxU3+PogE30P5sD1tkvdULQv1gf+Lkpgtoq5FMRaVGWHw9JurgL9Nsz tVRRJldonghoAKdgZPtg+axEMZIy5Rc1d2VFmihbNIY8L6v/8FS8SSI3Yv9ZdxB8mss7 rOwYFnZZml+lgjly1B5yepYXvpCrRKJc+TwRJrQGuea6qt8N9CckYjN1/Io3qGRYoLLK 9BQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:message-id:date:mime-version:user-agent :subject:content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=GRjbKlr19Mn5FxSswFnS14l/zAFp26BdYRhHkX31QzQ=; b=BM2FBSRz8S3Iwcb5BJhIc0aTe3+S5i/JHcWP5EbPqHl44iGNXq6v23YM/WNiYFzmg9 z6GJJMdyLgIWokpTBzM6+y1IxA9AMvCENraA/O7cFn1ambRXrO6nxYgMa9FWH6W6QWj7 oPDciOBsJBwFmIKVgOb1VlssNVcLm43p7ek+VWRqfixthX6fXqY1mWut2CUv0DwKZNmc CqIqPBoYVJwLNuSS/BAM3JkeLrHojLq0c3ccafuwaM+uwiS6eChbny8mBu/BDy+uCYFt 91IkcakRHo8rI2KJ+j59ftw4k8E8Bab1+v1SG0ct/BpU5eXlUu+7NELWlO9SVLPNvEL4 3MFA== X-Gm-Message-State: AOAM533hFNLSCct4bknq1QLZKA9DCQjVIF9wmKaZt+W2Y2TU3q8YHgBd F7pQSXNlGOZmECt5A45HZgHNM44XujXA/w== X-Google-Smtp-Source: ABdhPJzieD9OQcSSZ9JZSvdRZZLQuU62MR3EqRdMG4NpbV7ThNL3nBL3PxZ9ZjCW4OkiAVvynRC5Yw== X-Received: by 2002:a1c:545a:0:b0:38e:b1d6:9184 with SMTP id p26-20020a1c545a000000b0038eb1d69184mr22524419wmi.32.1650995361769; Tue, 26 Apr 2022 10:49:21 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:1c09:f536:3de6:228c? ([2001:b07:6468:f312:1c09:f536:3de6:228c]) by smtp.googlemail.com with ESMTPSA id u19-20020a05600c19d300b00393f081d49fsm3809222wmq.2.2022.04.26.10.49.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Apr 2022 10:49:21 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <7597fe2c-ce04-0e21-bd6c-4051d7d5101d@redhat.com> Date: Tue, 26 Apr 2022 19:49:20 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] KVM: x86/mmu: add lockdep check before lookup_address_in_mm() Content-Language: en-US To: Sean Christopherson , Mingwei Zhang Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm , LKML , Ben Gardon , David Matlack References: <20220327205803.739336-1-mizhang@google.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/28/22 20:15, Sean Christopherson wrote: >> lookup_address_in_mm() walks the host page table as if it is a >> sequence of_static_ memory chunks. This is clearly dangerous. > Yeah, it's broken. The proper fix is do something like what perf uses, or maybe > just genericize and reuse the code from commit 8af26be06272 > ("perf/core: Fix arch_perf_get_page_size()). > Indeed, KVM could use perf_get_pgtable_size(). The conversion from the result of *_leaf_size() to level is basically (ctz(size) - 12) / 9. Alternatively, there are the three difference between perf_get_page_size() and lookup_address_in_pgd(): * the *_offset_lockless() macros, which are unnecessary on x86 * READ_ONCE, which is important but in practice unlikely to make a difference * local_irq_{save,restore} around the walk The last is the important one and it should be added to lookup_address_in_pgd(). Paolo