From patchwork Fri Dec 3 19:29:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 12655727 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 71014C433EF for ; Fri, 3 Dec 2021 19:29:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1382806AbhLCTc1 (ORCPT ); Fri, 3 Dec 2021 14:32:27 -0500 Received: from mga06.intel.com ([134.134.136.31]:24105 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1382867AbhLCTc0 (ORCPT ); Fri, 3 Dec 2021 14:32:26 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10187"; a="297841054" X-IronPort-AV: E=Sophos;i="5.87,284,1631602800"; d="scan'208";a="297841054" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2021 11:29:02 -0800 X-IronPort-AV: E=Sophos;i="5.87,284,1631602800"; d="scan'208";a="501304739" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.25]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Dec 2021 11:29:01 -0800 Subject: [PATCH 1/2] cxl/pci: Implement Interface Ready Timeout From: Dan Williams To: linux-cxl@vger.kernel.org Cc: Ben Widawsky , ben.widawsky@intel.com, Jonathan.Cameron@huawei.com, alison.schofield@intel.com, ira.weiny@intel.com, vishal.l.verma@intel.com Date: Fri, 03 Dec 2021 11:29:01 -0800 Message-ID: <163855974164.1338601.11643774914793606293.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <163855973642.1338601.12855868083437118567.stgit@dwillia2-desk3.amr.corp.intel.com> References: <163855973642.1338601.12855868083437118567.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-cxl@vger.kernel.org From: Ben Widawsky The original driver implementation used the doorbell timeout for the Mailbox Interface Ready bit to piggy back off of, since the latter does not have a defined timeout. This functionality, introduced in commit 8adaf747c9f0 ("cxl/mem: Find device capabilities"), needs improvement as the recent "Add Mailbox Ready Time" ECN timeout indicates that the mailbox ready time can be significantly longer that 2 seconds. While the specification limits the maximum timeout to 256s, the cxl_pci driver gives up on the mailbox after 60s. This value corresponds with important timeout values already present in the kernel. A module parameter is provided as an emergency override. Signed-off-by: Ben Widawsky [djbw: add modparam, drop check_device_status()] Signed-off-by: Dan Williams Reviewed-by: Jonathan Cameron --- drivers/cxl/pci.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c index 8dc91fd3396a..519795432708 100644 --- a/drivers/cxl/pci.c +++ b/drivers/cxl/pci.c @@ -1,7 +1,9 @@ // SPDX-License-Identifier: GPL-2.0-only /* Copyright(c) 2020 Intel Corporation. All rights reserved. */ #include +#include #include +#include #include #include #include @@ -35,6 +37,19 @@ /* CXL 2.0 - 8.2.8.4 */ #define CXL_MAILBOX_TIMEOUT_MS (2 * HZ) +/* + * CXL 2.0 ECN "Add Mailbox Ready Time" defines a capability field to + * dictate how long to wait for the mailbox to become ready. The new + * field allows the device to tell software the amount of time to wait + * before mailbox ready. This field allows for up to 255 seconds. 255 + * seconds is unreasonable long, and longer than other default timeouts + * in the OS. Use the more sane, 60 seconds instead. + */ +static unsigned short mbox_ready_timeout = 60; +module_param(mbox_ready_timeout, ushort, 0600); +MODULE_PARM_DESC(mbox_ready_timeout, + "seconds to wait for mailbox ready status"); + static int cxl_pci_mbox_wait_for_doorbell(struct cxl_dev_state *cxlds) { const unsigned long start = jiffies; @@ -281,6 +296,25 @@ static int cxl_pci_mbox_send(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *c static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds) { const int cap = readl(cxlds->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET); + unsigned long timeout; + u64 md_status; + + timeout = jiffies + mbox_ready_timeout * HZ; + do { + md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET); + if (md_status & CXLMDEV_MBOX_IF_READY) + break; + if (msleep_interruptible(100)) + break; + } while (!time_after(jiffies, timeout)); + + if (!(md_status & CXLMDEV_MBOX_IF_READY)) { + dev_err(cxlds->dev, + "timeout awaiting mailbox ready, device state:%s%s\n", + md_status & CXLMDEV_DEV_FATAL ? " fatal" : "", + md_status & CXLMDEV_FW_HALT ? " firmware-halt" : ""); + return -EIO; + } cxlds->mbox_send = cxl_pci_mbox_send; cxlds->payload_size =