From patchwork Thu Oct 12 14:37:44 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 13419346 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 68EB1CDB46E for ; Thu, 12 Oct 2023 14:50:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=NCgCc2gjXby/8hOwcdYfNQrDzCB2b2+qoVcB7qIYvYU=; b=jn3sewyDkxsp0c oI+uohkFFUYgqlZEkGySU9+vRYQKyC4HRFxltunqWM2a0uqhQIaey0vXvJMljA3MOcxFrRGmAHSdc JECBkWMHAb/fUhqeLJaNYrMGxAzuAD5Wr0UhsxJkuPsuBKdtA1qpfDZjrCqfx5M+RAkvLE9d7no6q qj/+XAtp/G+uC+brHeghZom22Hl0ZT11KyyeKNYHqZVCfC02pVNIVbS5wOvZnQtgMLJC2bbqLWJTC YqPrXaC+E2DU1rE5eXTt5Px+W/ZbAjih+T/Oi6dfoA3xzkLyPQ43Ht+2CkE8sC1YhWAY3MwG14pFb U6PsVyAEh59aOvsN3alQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qqx0k-001DUL-1N; Thu, 12 Oct 2023 14:50:02 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qqx0g-001DTH-1W for linux-riscv@lists.infradead.org; Thu, 12 Oct 2023 14:50:00 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id E22ABB82458; Thu, 12 Oct 2023 14:49:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FDD7C433C8; Thu, 12 Oct 2023 14:49:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697122196; bh=WqvrIw3PkN3YYn1wVpzhO2s/Fo/gP7GkrtfWS3/rmZA=; h=From:To:Cc:Subject:Date:From; b=enA3mxvR1zssOjbMXwEkzY9UzGSeZWl8gFLi51c+AwxhAtznYQ+wxowCIkgqt5gCu SerfeCocbYsySI2epiFJ4mrEWZN5FY9S6ql3+YOJlO2P+YnDesvFUL0aIiELNvIhPW 7/eh5/rZebfsGWqxsyNRvXSmvH8qPbT49rtiagODqPdOyuIaBxjt1f5jxLkbNsTXwv gXuzIkLSbHF7y1SThaLtR95hjW7xTIPdcQovCr8Iqx8zEY0FvjZZx3AHNzukqY20JJ xE/wAG61GALMnatOvFTjz+SvTEzRmJ+sABCXrE6y3VK97EWnpuM3eNNl0J6faSiyKl F2i/sBbGz49eA== From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: Guo Ren , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 0/2] riscv: errata: thead: use riscv_nonstd_cache_ops for CMO Date: Thu, 12 Oct 2023 22:37:44 +0800 Message-Id: <20231012143746.454-1-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20231012_074958_746936_6B99AD3B X-CRM114-Status: UNSURE ( 9.89 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Previously, we use alternative mechanism to dynamically patch the CMO operations for THEAD C906/C910 during boot for performance reason. But as pointed out by Arnd, "there is already a significant cost in accessing the invalidated cache lines afterwards, which is likely going to be much higher than the cost of an indirect branch". And indeed, there's no performance difference with GMAC and EMMC per my test on Sipeed Lichee Pi 4A board. Use riscv_nonstd_cache_ops for THEAD C906/C910 CMO to simplify the alternative code, and to acchieve Arnd's goal -- "I think moving the THEAD ops at the same level as all nonstandard operations makes sense, but I'd still leave CMO as an explicit fast path that avoids the indirect branch. This seems like the right thing to do both for readability and for platforms on which the indirect branch has a noticeable overhead." To make bisect easy, I use two patches here: patch1 does the conversion which just mimics current CMO behavior via. riscv_nonstd_cache_ops, I assume no functionalities changes. patch2 uses T-HEAD PA based CMO instructions so that we don't need to covert PA to VA. Hi Guo, I didn't use wback_inv for wback as you suggested during v1 reviewing, this can be left as future optimizations. Thanks since v3: - collect Reviewed-by tag since v2: - collect Reviewed-by tag (but missed them in fact) - fix typo since v1: - collect Tested-by tag - add patch2 to use T-HEAD PA based CMO instructions. Jisheng Zhang (2): riscv: errata: thead: use riscv_nonstd_cache_ops for CMO riscv: errata: thead: use pa based instructions for CMO arch/riscv/Kconfig.errata | 1 + arch/riscv/errata/thead/errata.c | 69 +++++++++++++++++++++++++++- arch/riscv/include/asm/errata_list.h | 50 +++----------------- 3 files changed, 74 insertions(+), 46 deletions(-)