From patchwork Fri Nov 18 02:00:13 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiamei Xie X-Patchwork-Id: 13056136 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.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 D7C3AC43217 for ; Fri, 18 Nov 2022 02:01:04 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.445403.700550 (Exim 4.92) (envelope-from ) id 1ovqgJ-0004hN-DC; Fri, 18 Nov 2022 02:00:39 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 445403.700550; Fri, 18 Nov 2022 02:00:39 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ovqgJ-0004hF-7Q; Fri, 18 Nov 2022 02:00:39 +0000 Received: by outflank-mailman (input) for mailman id 445403; Fri, 18 Nov 2022 02:00:38 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ovqgI-0004h6-Ti for xen-devel@lists.xenproject.org; Fri, 18 Nov 2022 02:00:38 +0000 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by se1-gles-sth1.inumbo.com (Halon) with ESMTP id ca46a538-66e4-11ed-91b6-6bf2151ebd3b; Fri, 18 Nov 2022 03:00:35 +0100 (CET) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 07F7823A; Thu, 17 Nov 2022 18:00:41 -0800 (PST) Received: from a015971.shanghai.arm.com (unknown [10.169.188.104]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 54A3A3F587; Thu, 17 Nov 2022 18:00:32 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: ca46a538-66e4-11ed-91b6-6bf2151ebd3b From: Jiamei Xie To: xen-devel@lists.xenproject.org Cc: Jiamei Xie , Stefano Stabellini , Julien Grall , Bertrand Marquis , Volodymyr Babchuk , Wei Chen Subject: Date: Fri, 18 Nov 2022 10:00:13 +0800 Message-Id: <20221118020013.125987-1-jiamei.xie@arm.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Date: Thu, 17 Nov 2022 11:07:12 +0800 Subject: [PATCH] xen/arm: vpl011: Make access to DMACR write-ignore When the guest kernel enables DMA engine with "CONFIG_DMA_ENGINE=y", Linux SBSA PL011 driver will access PL011 DMACR register in some functions. As chapter "B Generic UART" in "ARM Server Base System Architecture"[1] documentation describes, SBSA UART doesn't support DMA. In current code, when the kernel tries to access DMACR register, Xen will inject a data abort: Unhandled fault at 0xffffffc00944d048 Mem abort info: ESR = 0x96000000 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x00: ttbr address size fault Data abort info: ISV = 0, ISS = 0x00000000 CM = 0, WnR = 0 swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000020e2e000 [ffffffc00944d048] pgd=100000003ffff803, p4d=100000003ffff803, pud=100000003ffff803, pmd=100000003fffa803, pte=006800009c090f13 Internal error: ttbr address size fault: 96000000 [#1] PREEMPT SMP ... Call trace: pl011_stop_rx+0x70/0x80 tty_port_shutdown+0x7c/0xb4 tty_port_close+0x60/0xcc uart_close+0x34/0x8c tty_release+0x144/0x4c0 __fput+0x78/0x220 ____fput+0x1c/0x30 task_work_run+0x88/0xc0 do_notify_resume+0x8d0/0x123c el0_svc+0xa8/0xc0 el0t_64_sync_handler+0xa4/0x130 el0t_64_sync+0x1a0/0x1a4 Code: b9000083 b901f001 794038a0 8b000042 (b9000041) ---[ end trace 83dd93df15c3216f ]--- note: bootlogd[132] exited with preempt_count 1 /etc/rcS.d/S07bootlogd: line 47: 132 Segmentation fault start-stop-daemon As discussed in [2], this commit makes the access to DMACR register write-ignore as an improvement. [1] https://developer.arm.com/documentation/den0094/c/?lang=en [2] https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2211161552420.4020@ubuntu-linux-20-04-desktop/ Signed-off-by: Jiamei Xie --- xen/arch/arm/vpl011.c | 1 + 1 file changed, 1 insertion(+) diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c index 43522d48fd..80d00b3052 100644 --- a/xen/arch/arm/vpl011.c +++ b/xen/arch/arm/vpl011.c @@ -463,6 +463,7 @@ static int vpl011_mmio_write(struct vcpu *v, case FR: case RIS: case MIS: + case DMACR: goto write_ignore; case IMSC: