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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05743C433FE for ; Tue, 5 Apr 2022 08:57:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343567AbiDEI5E (ORCPT ); Tue, 5 Apr 2022 04:57:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235027AbiDEIOp (ORCPT ); Tue, 5 Apr 2022 04:14:45 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57F3D9D0E1; Tue, 5 Apr 2022 01:03:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9B26F61684; Tue, 5 Apr 2022 08:03:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A5E5BC385A3; Tue, 5 Apr 2022 08:03:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649145795; bh=k43HI1oa+1ay+oQjwrj4y1FFW04YWbKgIhD+6XlwZdk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tQTFSQ/RioE/keFYc6rAfshcuiwf8WZPKLQ5ntX6GTFdicRImtJReBohnYaUToybr bdomr0XOV1fv3EmbJL1BzKimvCxO3G3JE2H7rDjYYTLPyfwsy+NhszBY2Ybhz08IVt BNZ/4ozoke63njsGcb3NzaoYkdlRkj5J4ZkTyiTA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jonathan Cameron , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Ben Widawsky , Dan Williams , Sasha Levin Subject: [PATCH 5.17 0532/1126] cxl/regs: Fix size of CXL Capability Header Register Date: Tue, 5 Apr 2022 09:21:19 +0200 Message-Id: <20220405070423.246673251@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Jonathan Cameron [ Upstream commit 74b0fe80409733055971bbfaf33c80a33fddeeb3 ] In CXL 2.0, 8.2.5.1 CXL Capability Header Register: this register is given as 32 bits. 8.2.3 which covers the CXL 2.0 Component registers, including the CXL Capability Header Register states that access restrictions specified in Section 8.2.2 apply. 8.2.2 includes: * A 32 bit register shall be accessed as a 4 Byte quantity. ... If these rules are not followed, the behavior is undefined. Discovered during review of CXL QEMU emulation. Alex Bennée pointed out there was a comment saying that 4 byte registers must be read with a 4 byte read, but 8 byte reads were being emulated. https://lore.kernel.org/qemu-devel/87bkzyd3c7.fsf@linaro.org/ Fixing that, led to this code failing. Whilst a given hardware implementation 'might' work with an 8 byte read, it should not be relied upon. The QEMU emulation v5 will return 0 and log the wrong access width. The code moved, so one fixes tag for where this will directly apply and also a reference to the earlier introduction of the code for backports. Fixes: 0f06157e0135 ("cxl/core: Move register mapping infrastructure") Fixes: 08422378c4ad ("cxl/pci: Add HDM decoder capabilities") Signed-off-by: Jonathan Cameron Cc: Alex Bennée Reviewed-by: Ben Widawsky Link: https://lore.kernel.org/r/20220201153437.2873-1-Jonathan.Cameron@huawei.com Signed-off-by: Dan Williams Signed-off-by: Sasha Levin --- drivers/cxl/core/regs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c index cdc0b75d94f2..6a18ff8739e0 100644 --- a/drivers/cxl/core/regs.c +++ b/drivers/cxl/core/regs.c @@ -35,7 +35,7 @@ void cxl_probe_component_regs(struct device *dev, void __iomem *base, struct cxl_component_reg_map *map) { int cap, cap_count; - u64 cap_array; + u32 cap_array; *map = (struct cxl_component_reg_map) { 0 }; @@ -45,7 +45,7 @@ void cxl_probe_component_regs(struct device *dev, void __iomem *base, */ base += CXL_CM_OFFSET; - cap_array = readq(base + CXL_CM_CAP_HDR_OFFSET); + cap_array = readl(base + CXL_CM_CAP_HDR_OFFSET); if (FIELD_GET(CXL_CM_CAP_HDR_ID_MASK, cap_array) != CM_CAP_HDR_CAP_ID) { dev_err(dev, -- 2.34.1