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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0806C433EF for ; Fri, 15 Oct 2021 02:47:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D932611C5 for ; Fri, 15 Oct 2021 02:47:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232974AbhJOCtK (ORCPT ); Thu, 14 Oct 2021 22:49:10 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:54335 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229704AbhJOCtI (ORCPT ); Thu, 14 Oct 2021 22:49:08 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R641e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=xianting.tian@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0Us1cFSh_1634266020; Received: from localhost(mailfrom:xianting.tian@linux.alibaba.com fp:SMTPD_---0Us1cFSh_1634266020) by smtp.aliyun-inc.com(127.0.0.1); Fri, 15 Oct 2021 10:47:01 +0800 From: Xianting Tian To: gregkh@linuxfoundation.org, jirislaby@kernel.org, amit@kernel.org, arnd@arndb.de, osandov@fb.com Cc: shile.zhang@linux.alibaba.com, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Xianting Tian Subject: [PATCH v11 0/3] make hvc pass dma capable memory to its backend Date: Fri, 15 Oct 2021 10:46:55 +0800 Message-Id: <20211015024658.1353987-1-xianting.tian@linux.alibaba.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear all, This patch series make hvc framework pass DMA capable memory to put_chars() of hvc backend(eg, virtio-console), and revert commit c4baad5029 ("virtio-console: avoid DMA from stack”) V1 virtio-console: avoid DMA from vmalloc area https://lkml.org/lkml/2021/7/27/494 For v1 patch, Arnd Bergmann suggests to fix the issue in the first place: Make hvc pass DMA capable memory to put_chars() The fix suggestion is included in v2. V2 [PATCH 1/2] tty: hvc: pass DMA capable memory to put_chars() https://lkml.org/lkml/2021/8/1/8 [PATCH 2/2] virtio-console: remove unnecessary kmemdup() https://lkml.org/lkml/2021/8/1/9 For v2 patch, Arnd Bergmann suggests to make new buf part of the hvc_struct structure, and fix the compile issue. The fix suggestion is included in v3. V3 [PATCH v3 1/2] tty: hvc: pass DMA capable memory to put_chars() https://lkml.org/lkml/2021/8/3/1347 [PATCH v3 2/2] virtio-console: remove unnecessary kmemdup() https://lkml.org/lkml/2021/8/3/1348 For v3 patch, Jiri Slaby suggests to make 'char c[N_OUTBUF]' part of hvc_struct, and make 'hp->outbuf' aligned and use struct_size() to calculate the size of hvc_struct. The fix suggestion is included in v4. V4 [PATCH v4 0/2] make hvc pass dma capable memory to its backend https://lkml.org/lkml/2021/8/5/1350 [PATCH v4 1/2] tty: hvc: pass DMA capable memory to put_chars() https://lkml.org/lkml/2021/8/5/1351 [PATCH v4 2/2] virtio-console: remove unnecessary kmemdup() https://lkml.org/lkml/2021/8/5/1352 For v4 patch, Arnd Bergmann suggests to introduce another array(cons_outbuf[]) for the buffer pointers next to the cons_ops[] and vtermnos[] arrays. This fix included in this v5 patch. V5 Arnd Bergmann suggests to use "L1_CACHE_BYTES" as dma alignment, use 'sizeof(long)' as dma alignment is wrong. fix it in v6. V6 It contains coding error, fix it in v7 and it worked normally according to test result. V7 Greg KH suggests to add test and code review developer, Jiri Slaby suggests to use lockless buffer and fix dma alignment in separate patch. fix above things in v8. V8 This contains coding error when switch to use new buffer. fix it in v9. V9 It didn't make things much clearer, it needs add more comments for new added buf. Add use lock to protect new added buffer. fix in v10. V10 Remove 'char outchar' and its lock from hvc_struct, adjust hvc_struct and use pahole to display the struct layout. fix it in v11. ********TEST STEPS********* 1, config guest console=hvc0 2, start guest 3, login guest Welcome to Buildroot buildroot login: root # # cat /proc/cmdline console=hvc0 root=/dev/vda rw init=/sbin/init # drivers/tty/hvc/hvc_console.c | 36 ++++++++++++++++++++--------------- drivers/tty/hvc/hvc_console.h | 21 +++++++++++++++++++- drivers/char/virtio_console.c | 12 ++---------- 3 file changed