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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 42132C433FE for ; Tue, 22 Nov 2022 13:21:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oxTD8-0007RV-JL; Tue, 22 Nov 2022 08:21:14 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oxTD0-0007Qp-Kz for qemu-devel@nongnu.org; Tue, 22 Nov 2022 08:21:07 -0500 Received: from mail-pl1-x636.google.com ([2607:f8b0:4864:20::636]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1oxTCv-0003bT-MF for qemu-devel@nongnu.org; Tue, 22 Nov 2022 08:21:06 -0500 Received: by mail-pl1-x636.google.com with SMTP id b21so13600991plc.9 for ; Tue, 22 Nov 2022 05:21:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=RQLrlo4/7CO16+OxQa2JCx3ver4DOMuBiUaxnsHtFt0=; b=AmsmZIpghxAVEmTg2kK2oyUcXKY8TQ6t1IQV5wE1Od0O1MCN6dYVnE8GpPbCX6CYbc wcJOU2mQtYeCHZXEF3B8jqrrMRHbGoLcZ8iZ8McXkgohWuhbvhOihewieeX+Avd/RrgR AhB2Fj6kADXKDBwhBHo741rR45NpFSTskQmrXfKMOM6q4u8IoXbIPwmP0IAVm+Es/KY8 AX9vlNix5rN5+ksJSZb1xIQ7q6GjCegDhb3QZ4HkMceTiMwo0eu9i0rzr+rcHVBPL619 y+X8SYmlZXtho116hmtpau+XZWF8XWO3LLrgUfh/4OyuZr3PA9zUcMd9KvVNDR8YlY+m Xzsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=RQLrlo4/7CO16+OxQa2JCx3ver4DOMuBiUaxnsHtFt0=; b=RyNT5QJRm/qPjX8tksF4zhLEI6nQegmx15G6OslzmkIUQserDYIQr9q0CluJOJ5kKG xMvmFYihy8qy7JYtw7hBtaxXvZgFPbCpegl58DY7fRk6QBdlAMoABqksCJWXsOeHUYVW ILVR6loYc8K3g2APfnWTsC1YqbNJxFP72gPauO5S1X+Mpj94A3mXS8WadR77o7BNRKDj 5vkD7iTHMHVEg5MwsvpqC2QKw3plC6kSHRXBaT6dntM0NKucKCnyh/PyHNzrCCXaxL+V dVeYrGEKk0+1iTKsvFcQQ6Qlcclg0aR9u7EMDUn5PGWQzJMObyKivPopy8QnC6FrkrHn YHSw== X-Gm-Message-State: ANoB5pm+ziojnUUl/mR800JSw/dm8YwplM2xAzdDNc4W2MsYDszJfpww 0XUQa9jYRbF6CkAMAgXwg6o8zMOCqEtZhisuHCGGIA== X-Google-Smtp-Source: AA0mqf4d9qPzvCiGx/cra3tnnX/Li1ftDALGvmphhIfaADp8XZXfkVEb+lDPpmWGk/mqaHUaODZPXJXDZpTGvhh2lGQ= X-Received: by 2002:a17:902:b691:b0:188:5240:50ec with SMTP id c17-20020a170902b69100b00188524050ecmr4171470pls.168.1669123259914; Tue, 22 Nov 2022 05:20:59 -0800 (PST) MIME-Version: 1.0 References: <20221121174326.68520-1-ardb@kernel.org> In-Reply-To: From: Peter Maydell Date: Tue, 22 Nov 2022 13:20:48 +0000 Message-ID: Subject: Re: [PATCH] target/arm: Use signed quantity to represent VMSAv8-64 translation level To: Ard Biesheuvel Cc: qemu-devel@nongnu.org, =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= , Richard Henderson Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::636; envelope-from=peter.maydell@linaro.org; helo=mail-pl1-x636.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, 21 Nov 2022 at 19:02, Ard Biesheuvel wrote: > > On Mon, 21 Nov 2022 at 19:51, Peter Maydell wrote: > > > > On Mon, 21 Nov 2022 at 17:43, Ard Biesheuvel wrote: > > > > > > The LPA2 extension implements 52-bit virtual addressing for 4k and 16k > > > translation granules, and for the former, this means an additional level > > > of translation is needed. This means we start counting at -1 instead of > > > 0 when doing a walk, and so 'level' is now a signed quantity, and should > > > be typed as such. So turn it from uint32_t into int32_t. > > > > > > > Does this cause any visible wrong behaviour, or is it just > > a cleanup thing ? > > > > No, 5 level paging is completely broken because of this, given that > the 'level < 3' tests give the wrong result for (uint32_t)-1 Right, thanks. This seems like a bug worth fixing for 7.2. We should make 'uint32_t startlevel' also an int32_t for consistency, I think, given that it is also sometimes negative, though in that case it doesn't get used in any comparisons so it's not going to cause wrong behaviour. thanks -- PMM