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 D79A0C433EF for ; Thu, 5 May 2022 11:54:50 +0000 (UTC) Received: from localhost ([::1]:58434 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nma4I-0003l6-0U for qemu-devel@archiver.kernel.org; Thu, 05 May 2022 07:54:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48002) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nma2T-0001c7-5v for qemu-devel@nongnu.org; Thu, 05 May 2022 07:52:57 -0400 Received: from us-smtp-delivery-74.mimecast.com ([170.10.129.74]:30844) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nma2R-0001tO-IA for qemu-devel@nongnu.org; Thu, 05 May 2022 07:52:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651751574; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GOewFIR/AyhFTSTNUniSTH4HDi0aAiO1qU8V2oBzj+w=; b=AvPoOKl/5x0TkAST+D2MYsgxH5HykLrexIqll4ad1bUkzvAX/xq7A3UMAMe859bBRSj3me +CcVBBI2/Klm//Yx6f4ab6iOtPwR133bZecq6kMrQVQj3pGgCTmClaaR5Mmfe5654sKlbB XOpK/vM/NQ5GLH7XDwLjl2EFxo6L3/E= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-421-ekTcBkXsPZaqLFO8Pn8YdA-1; Thu, 05 May 2022 07:52:51 -0400 X-MC-Unique: ekTcBkXsPZaqLFO8Pn8YdA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5CEE7185A79C; Thu, 5 May 2022 11:52:51 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.36.112.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 139B0463E1F; Thu, 5 May 2022 11:52:51 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id 0C88321E6880; Thu, 5 May 2022 13:52:50 +0200 (CEST) From: Markus Armbruster To: Peter Maydell Cc: qemu-devel@nongnu.org, Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Mark Cave-Ayland , John Snow , =?utf-8?Q?Herv=C3=A9?= Poussineau , Aleksandar Rikalo , qemu-block@nongnu.org Subject: Re: [PATCH v2] hw/block/fdc-sysbus: Always mark sysbus floppy controllers as not having DMA References: <20220505101842.2757905-1-peter.maydell@linaro.org> Date: Thu, 05 May 2022 13:52:50 +0200 In-Reply-To: <20220505101842.2757905-1-peter.maydell@linaro.org> (Peter Maydell's message of "Thu, 5 May 2022 11:18:42 +0100") Message-ID: <87ee18urfx.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 Received-SPF: pass client-ip=170.10.129.74; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-74.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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" Peter Maydell writes: > The sysbus floppy controllers (devices sysbus-fdc and sun-fdtwo) > don't support DMA. The core floppy controller code expects this to > be indicated by setting FDCtrl::dma_chann to -1. This used to be > done in the device instance_init functions sysbus_fdc_initfn() and > sun4m_fdc_initfn(), but in commit 1430759ec3e we refactored this code > and accidentally lost the setting of dma_chann. Worth a Fixes: 1430759ec3e4cb92da224d739c914a0e8d78d786 tag? > > For sysbus-fdc this has no ill effects because we were redundantly > also setting dma_chann in fdctrl_init_sysbus(), but for sun-fdtwo > this means that guests which try to enable DMA on the floppy > controller will cause QEMU to crash because FDCtrl::dma is NULL. > > Set dma_chann to -1 in the common instance init, and remove the > redundant code in fdctrl_init_sysbus() that is also setting it. > > There is a six-year-old FIXME comment in the jazz board code to the > effect that in theory it should support doing DMA via a custom DMA > controller. If anybody ever chooses to fix that they can do it by > adding support for setting both FDCtrl::dma_chann and FDCtrl::dma. > (A QOM link property 'dma-controller' on the sysbus device which can > be set to an instance of IsaDmaClass is probably the way to go.) > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/958 > Signed-off-by: Peter Maydell > Reviewed-by: Philippe Mathieu-Daud=C3=A9 > Reviewed-by: Mark Cave-Ayland