From patchwork Thu Oct 12 14:14:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 13419322 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 7309CCDB46E for ; Thu, 12 Oct 2023 14:27:31 +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=g+mNiWI56Iv0rwRL5W+1QiN6QyYkudkGu6ezNkIAMM0=; b=n6yXwrigASEsWk YeEfKDNMjgUifZ+bVcds2MhUMpGJE/0i0R58pvv0aI6n2gHg49z4t+L7vwSBUWTuk9WFvOp7cI4yB 2Fb87IWqSlkOtVkS7g7HO9d0jHhuO6jsScHB/HrhVvEzcGuB/N9Xzt6ayCJtgupwIziBH+/YwXcx2 +ZmSf1mJzyjaI68rPxGxjqLofRs9ni0X9stcBXaC/ORV0H9jJ509nLsuqS7OxBQ8XgD1A9+8wQ1uo Uj6BvluoOw3OiZPDam/GhITFB/8nix27oNEKP8skz5EJJStd+YiSrnlooXZLMWz39OD/7EKxiUV3v r6vF5gly6DV4FvdkXADA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qqwen-001BA3-3C; Thu, 12 Oct 2023 14:27:21 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qqwek-001B8j-2h for linux-riscv@lists.infradead.org; Thu, 12 Oct 2023 14:27:20 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id D6A0DCE290F; Thu, 12 Oct 2023 14:27:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80AA1C433C7; Thu, 12 Oct 2023 14:27:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697120836; bh=FHPuVYx77onrE1BKDhkCrW4jZHv+uXzoeFVCq11iTOg=; h=From:To:Cc:Subject:Date:From; b=aYm5uNnSVfHV/ccqtOGe+9g1qSe83cQKd7D0+PJGwoe4v8O4Bo7daTpi2JeIT/a9S NK9Mdu+ihT6zPnEuOct2hMPx2lmp9FbNLLcAhtu0lTX4l2AbfNtc/tgrU/+MT2YFby v93vr4xpdUPQiKCgvS31J7njcy/4H5AzRtz/o2hL7o+O9/iMnOEOBEXn7r8WFqs7vv Tx2PeRlHhx0LC+otsXW8t/pUu4s/Bb3k7r7LkbMf74uiKKGvFnf23izG8LG4/h4uR7 awXnLaQdWgR9CSHKGfMaJVtCwV8PfSVNvFJJx6+JqTZZpWIx+MZYDMWmKdutvpASED slbReTrzJJFeQ== 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 v3 0/2] riscv: errata: thead: use riscv_nonstd_cache_ops for CMO Date: Thu, 12 Oct 2023 22:14:54 +0800 Message-Id: <20231012141456.4078-1-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_072719_076681_77C80FD0 X-CRM114-Status: UNSURE ( 9.92 ) 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 v2: - collect Reviewed-by tag - 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(-)