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spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From:In-Reply-To: References:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=haPC8c0fH7rZxyRnLEZO6zJ7m3ichc7YaFFI6nqkN8w=; b=YMA4qDReIOkuAApHlYaQHJOLQ 7qh6JUWy9qno9cVGm1ppSWTrKlgyl8wDQH0W4wXgxiZwU9m3jX09R1SMomq9h6YW1sT7rpH5Hh4bX XU2CZm++QhU9UrZuJQER6OVwN8zdJuDqdLLgdJ8q2MUlj7ryg5yvopGtUWjNvEoGJi4vdAsHUjqez yqQoL4eop79w5BFY1PnLiC9ij2ox+ejfMqI92uzR1ujrVeKS0pHayzBYYo3xNtkrM3nputVxk+3X6 APjOcicUmlZ5+VUCcjGvGYuPN8pAi/WTV9FOX/cosfpmQbrXlHcxkFEqWixwOY1gXRwDl/UDBLESd wsXbrSblA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lLl96-00FdUF-Hf; Mon, 15 Mar 2021 11:12:24 +0000 Received: from mout.kundenserver.de ([212.227.126.131]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lLl8g-00FdPN-Us for linux-arm-kernel@lists.infradead.org; Mon, 15 Mar 2021 11:12:15 +0000 Received: from mail-ot1-f44.google.com ([209.85.210.44]) by mrelayeu.kundenserver.de (mreue011 [213.165.67.97]) with ESMTPSA (Nemesis) id 1MirX2-1lyPny0sBI-00exBi for ; Mon, 15 Mar 2021 12:11:54 +0100 Received: by mail-ot1-f44.google.com with SMTP id 75so6831473otn.4 for ; Mon, 15 Mar 2021 04:11:53 -0700 (PDT) X-Gm-Message-State: AOAM530zx+DepGmHlrIKEBL+eGlcc2OqSboMfxCedKPMSVMubpmDspt3 TS5lyif2HawbEtrFxcXJwhCTZAmqgM7f6BQbSMA= X-Google-Smtp-Source: ABdhPJwgFNAyEVxZiEuwwAFSd1LDIRQSQ4zi7ZvOwBbILrKBjO6+lOmx4xH7rEw7RUsB/mp58wpwWDncRUhPJRN7aEM= X-Received: by 2002:a9d:6341:: with SMTP id y1mr13488018otk.210.1615806712855; Mon, 15 Mar 2021 04:11:52 -0700 (PDT) MIME-Version: 1.0 References: <48347b4d-9194-16f2-95a0-c3eb55ca9a80@huawei.com> <56d33822-e577-c8a8-673b-675d6920c379@huawei.com> In-Reply-To: <56d33822-e577-c8a8-673b-675d6920c379@huawei.com> From: Arnd Bergmann Date: Mon, 15 Mar 2021 12:11:36 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: arm64 syzbot instances To: John Garry Cc: Dmitry Vyukov , Mark Rutland , Marc Zyngier , Will Deacon , Ard Biesheuvel , Linux ARM , syzkaller , LKML , Peter Maydell , =?UTF-8?B?QWxleCBCZW5uw6ll?= , Jiahui Cen X-Provags-ID: V03:K1:SDSfsuK4nl7af/v/t7x5siBhhE1+k8uySM63/T5mY5CscCMqTHQ UEnatLpBSjFsY/C/M5p0fXDY3gT4zxAiBQCarchPGarD2m5GFRrUho3OfFNRbPmAz+hsiNA 2PPsceP2Oz0/pfs6T1zEjdMqEIrBpmak7UhoAFb7gvU8vWGczRdP+Cu6S0BtKAXOsROyLMd /rMAbR6rCZcL0+qopRsDA== X-UI-Out-Filterresults: notjunk:1;V03:K0:ys36yNZMLrs=:y2AsTbHW/Pivd65Z5w+g9l v/ATRSfTy5viEMkrd2JG4+u414VOQOAk9vTw1Q8nRKjTC+a16N55938WKtyNrzWxm7jbjFtv5 J1+rzR88jLMcz+Am37ND20X7T6Z/XofwojwqYTGiIhNIuY9Qmshk/10zhIEdByyzG/g8QE32L 6N+H7oVdZoxpWx3kjd4kmV3+FEUWKs6nryiZYJff8CoOqAr43TsZxzQG58I5PX8e+LIQgdu6z mhva+1wPqJMwfp2DGRva7eWXGvIeCBY8KjugQQ+/Mp0L8d5R8GvByVB7ivyN9m2rRXCw1D8pe 1dKKEp+14om/WIWejxrHR/Vdi/K/p94t+mfU15yGzr8XcmQjdmZOmaJ/MhY7HH6Dypy+TFPFt elWXR/GXhJoaUiIDuckQ9e/iYk4Bn/G4WWX5dvaZ52kROt1ehqLzyfANZOuxw1PLWmSm9+vOw P+YfiE2y04EQlBuoMMyx6he0ESp17nJThOQDYlEcNGV5p6swQk1Mg1cTOMjfopj0q4/6o0cLv riCR13yhRmQ1f2rRMxzcz6z2pq0ZdbLQNU2969i1PrL X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210315_111201_326666_C8309389 X-CRM114-Status: GOOD ( 32.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 15, 2021 at 11:29 AM John Garry wrote: > On 15/03/2021 10:01, Dmitry Vyukov wrote: > > On Mon, Mar 15, 2021 at 10:45 AM John Garry wrote: > >>>> It does not happen too often on syzbot so far, so let's try to do the > >>>> right thing first. > >>>> I've filed:https://bugs.launchpad.net/qemu/+bug/1918917 > >>>> with a link to this thread. To be fair, I don't fully understand what > >>>> I am talking about, I hope I proxied your description properly. > >>> Thanks, looks good. I provided a little more detail in a comment there. > >>> > >>> Arnd > >>> . > >>> > >> From looking at the bug report, my impression is that this is a qemu > >> issue, as the logical IO space is mapped to the PCI host bridge IO > >> space, and qemu does not handle accesses to that CPU addressable region > >> at all. As Arnd said. > >> > >> However, we really should not be accessing logical IO ports 0 or 0x2f8 > >> at all via ttyS3 if not enumerated from PCI device at that logical IO > >> port. That is what I think anyway, as who knows what device - if any - > >> really exists at that location. That is why I had this patch to just > >> stop accesses to legacy IO port regions on arm64: > >> > >> https://lore.kernel.org/lkml/1610729929-188490-2-git-send-email-john.garry@huawei.com/ > > Hi John, > > > > Thanks for the info. > > > > The patch is from January, but it's not merged yet, right? > > It will fix the crash we see, right? > > It's not merged, and it probably would solve this issue. But following > discussion with Arnd when it was originally posted, I still need to do > some analysis whether it is the proper thing to do. Right, it might be something we decide to do in order to intentionally break legacy ISA devices, but I don't think that patch should be necessary as a bugfix, given that the same devices on x86 just work. I think Huawei and some others have a BMC on either a PCI port or an LPC bridge, with PC style device emulation for things that might include VGA, serial, keyboard/mouse, RTC, IPMI, or ATAPI CDROM. In a properly designed system, these should all be described by the firmware if present, but today they should still work even if the firmware does not describe them (provided the driver looks at the correct address, which the 8250 driver did not). Arnd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel