From patchwork Mon Nov 28 20:36:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacob Keller X-Patchwork-Id: 13057932 X-Patchwork-Delegate: kuba@kernel.org 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 93AB5C433FE for ; Mon, 28 Nov 2022 20:37:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234194AbiK1UhG (ORCPT ); Mon, 28 Nov 2022 15:37:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234196AbiK1UhE (ORCPT ); Mon, 28 Nov 2022 15:37:04 -0500 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF1BC2C673 for ; Mon, 28 Nov 2022 12:37:02 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1669667822; x=1701203822; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=c15Xr5gDDr2PWpXmkejsIx81RNnE88Df+2C9wrSddQ4=; b=G34342SBm0dGBM3WnrWee6Eauw/1tvpWjsB3uoABKFWClkhRCmTopNl4 yFrXHSvTI5JnuPl24OwK5GNwYy0OECVmrL3elWD5mqjE545PBROAOKY42 1j+kJ/6oJkPO9feHuyZTvmS1ZgwcatGHjCoiH/Uijooro/d1cyoKL0cf1 TdzB4YC8k5Zq946fMCj3XxvIAuNJ+1M8CXwgyT0TSpbGiKHxfrKwbKQrp K8jkwNZpu8nmey2RlJBefTrOA0hOP6pxJgOyvTJMCtvgvClyubkSmcPwG PF6yjc2EjNBkDwgClMWjRz9N7Zf16miSFhVPaCam7eAcLXPP/GzHIP8CV w==; X-IronPort-AV: E=McAfee;i="6500,9779,10545"; a="379205397" X-IronPort-AV: E=Sophos;i="5.96,201,1665471600"; d="scan'208";a="379205397" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Nov 2022 12:36:59 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10545"; a="732286357" X-IronPort-AV: E=Sophos;i="5.96,201,1665471600"; d="scan'208";a="732286357" Received: from jekeller-desk.amr.corp.intel.com (HELO jekeller-desk.jekeller.internal) ([10.166.241.7]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Nov 2022 12:36:59 -0800 From: Jacob Keller To: netdev@vger.kernel.org Cc: Jacob Keller , Jiri Pirko , Jakub Kicinski Subject: [PATCH net-next v3 6/9] devlink: support directly reading from region memory Date: Mon, 28 Nov 2022 12:36:44 -0800 Message-Id: <20221128203647.1198669-7-jacob.e.keller@intel.com> X-Mailer: git-send-email 2.38.1.420.g319605f8f00e In-Reply-To: <20221128203647.1198669-1-jacob.e.keller@intel.com> References: <20221128203647.1198669-1-jacob.e.keller@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org To read from a region, user space must currently request a new snapshot of the region and then read from that snapshot. This can sometimes be overkill if user space only reads a tiny portion. They first create the snapshot, then request a read, then destroy the snapshot. For regions which have a single underlying "contents", it makes sense to allow supporting direct reading of the region data. Extend the DEVLINK_CMD_REGION_READ to allow direct reading from a region if requested via the new DEVLINK_ATTR_REGION_DIRECT. If this attribute is set, then perform a direct read instead of using a snapshot. Direct read is mutually exclusive with DEVLINK_ATTR_REGION_SNAPSHOT_ID, and care is taken to ensure that we reject commands which provide incorrect attributes. Regions must enable support for direct read by implementing the .read() callback function. If a region does not support such direct reads, a suitable extended error message is reported. Signed-off-by: Jacob Keller Reviewed-by: Jiri Pirko --- Changes since v2: * Switched to using a new DEVLINK_ATTR_REGION_DIRECT attribute, ensuring that user space is explicit in requesting direct access, and user space to determine when support exists in the kernel. * Fixed the capitalization of NL_SET_ERR_MSG .../networking/devlink/devlink-region.rst | 13 +++ include/net/devlink.h | 16 ++++ include/uapi/linux/devlink.h | 2 + net/core/devlink.c | 80 +++++++++++++++---- 4 files changed, 94 insertions(+), 17 deletions(-) diff --git a/Documentation/networking/devlink/devlink-region.rst b/Documentation/networking/devlink/devlink-region.rst index f06dca9a1eb6..9232cd7da301 100644 --- a/Documentation/networking/devlink/devlink-region.rst +++ b/Documentation/networking/devlink/devlink-region.rst @@ -31,6 +31,15 @@ in its ``devlink_region_ops`` structure. If snapshot id is not set in the ``DEVLINK_CMD_REGION_NEW`` request kernel will allocate one and send the snapshot information to user space. +Regions may optionally allow directly reading from their contents without a +snapshot. Direct read requests are not atomic. In particular a read request +of size 256 bytes or larger will be split into multiple chunks. If atomic +access is required, use a snapshot. A driver wishing to enable this for a +region should implement the ``.read`` callback in the ``devlink_region_ops`` +structure. User space can request a direct read by using the +``DEVLINK_ATTR_REGION_DIRECT`` attribute instead of specifying a snapshot +id. + example usage ------------- @@ -65,6 +74,10 @@ example usage $ devlink region read pci/0000:00:05.0/fw-health snapshot 1 address 0 length 16 0000000000000000 0014 95dc 0014 9514 0035 1670 0034 db30 + # Read from the region without a snapshot + $ devlink region read pci/0000:00:05.0/fw-health address 16 length 16 + 0000000000000010 0000 0000 ffff ff04 0029 8c00 0028 8cc8 + As regions are likely very device or driver specific, no generic regions are defined. See the driver-specific documentation files for information on the specific regions a driver supports. diff --git a/include/net/devlink.h b/include/net/devlink.h index 074a79b8933f..02528f736f65 100644 --- a/include/net/devlink.h +++ b/include/net/devlink.h @@ -650,6 +650,10 @@ struct devlink_info_req; * the data variable must be updated to point to the snapshot data. * The function will be called while the devlink instance lock is * held. + * @read: callback to directly read a portion of the region. On success, + * the data pointer will be updated with the contents of the + * requested portion of the region. The function will be called + * while the devlink instance lock is held. * @priv: Pointer to driver private data for the region operation */ struct devlink_region_ops { @@ -659,6 +663,10 @@ struct devlink_region_ops { const struct devlink_region_ops *ops, struct netlink_ext_ack *extack, u8 **data); + int (*read)(struct devlink *devlink, + const struct devlink_region_ops *ops, + struct netlink_ext_ack *extack, + u64 offset, u32 size, u8 *data); void *priv; }; @@ -670,6 +678,10 @@ struct devlink_region_ops { * the data variable must be updated to point to the snapshot data. * The function will be called while the devlink instance lock is * held. + * @read: callback to directly read a portion of the region. On success, + * the data pointer will be updated with the contents of the + * requested portion of the region. The function will be called + * while the devlink instance lock is held. * @priv: Pointer to driver private data for the region operation */ struct devlink_port_region_ops { @@ -679,6 +691,10 @@ struct devlink_port_region_ops { const struct devlink_port_region_ops *ops, struct netlink_ext_ack *extack, u8 **data); + int (*read)(struct devlink_port *port, + const struct devlink_port_region_ops *ops, + struct netlink_ext_ack *extack, + u64 offset, u32 size, u8 *data); void *priv; }; diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h index 498d0d5d0957..70191d96af89 100644 --- a/include/uapi/linux/devlink.h +++ b/include/uapi/linux/devlink.h @@ -610,6 +610,8 @@ enum devlink_attr { DEVLINK_ATTR_RATE_TX_PRIORITY, /* u32 */ DEVLINK_ATTR_RATE_TX_WEIGHT, /* u32 */ + DEVLINK_ATTR_REGION_DIRECT, /* flag */ + /* add new attributes above here, update the policy in devlink.c */ __DEVLINK_ATTR_MAX, diff --git a/net/core/devlink.c b/net/core/devlink.c index 22480c85a0d0..bb8b7e00f420 100644 --- a/net/core/devlink.c +++ b/net/core/devlink.c @@ -6515,6 +6515,26 @@ devlink_region_snapshot_fill(void *cb_priv, u8 *chunk, u32 chunk_size, return 0; } +static int +devlink_region_port_direct_fill(void *cb_priv, u8 *chunk, u32 chunk_size, + u64 curr_offset, struct netlink_ext_ack *extack) +{ + struct devlink_region *region = cb_priv; + + return region->port_ops->read(region->port, region->port_ops, extack, + curr_offset, chunk_size, chunk); +} + +static int +devlink_region_direct_fill(void *cb_priv, u8 *chunk, u32 chunk_size, + u64 curr_offset, struct netlink_ext_ack *extack) +{ + struct devlink_region *region = cb_priv; + + return region->ops->read(region->devlink, region->ops, extack, + curr_offset, chunk_size, chunk); +} + static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb, struct netlink_callback *cb) { @@ -6523,12 +6543,12 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb, u64 ret_offset, start_offset, end_offset = U64_MAX; struct nlattr **attrs = info->attrs; struct devlink_port *port = NULL; - struct devlink_snapshot *snapshot; + devlink_chunk_fill_t *region_cb; struct devlink_region *region; const char *region_name; struct devlink *devlink; unsigned int index; - u32 snapshot_id; + void *region_cb_priv; void *hdr; int err; @@ -6546,12 +6566,6 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb, goto out_unlock; } - if (!attrs[DEVLINK_ATTR_REGION_SNAPSHOT_ID]) { - NL_SET_ERR_MSG(cb->extack, "No snapshot id provided"); - err = -EINVAL; - goto out_unlock; - } - if (info->attrs[DEVLINK_ATTR_PORT_INDEX]) { index = nla_get_u32(info->attrs[DEVLINK_ATTR_PORT_INDEX]); @@ -6577,12 +6591,43 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb, } snapshot_attr = attrs[DEVLINK_ATTR_REGION_SNAPSHOT_ID]; - snapshot_id = nla_get_u32(snapshot_attr); - snapshot = devlink_region_snapshot_get_by_id(region, snapshot_id); - if (!snapshot) { - NL_SET_ERR_MSG_ATTR(cb->extack, snapshot_attr, "Requested snapshot does not exist"); - err = -EINVAL; - goto out_unlock; + if (!snapshot_attr) { + if (!nla_get_flag(attrs[DEVLINK_ATTR_REGION_DIRECT])) { + NL_SET_ERR_MSG(cb->extack, "No snapshot id provided"); + err = -EINVAL; + goto out_unlock; + } + + if (!region->ops->read) { + NL_SET_ERR_MSG(cb->extack, "Requested region does not support direct read"); + err = -EOPNOTSUPP; + goto out_unlock; + } + + if (port) + region_cb = &devlink_region_port_direct_fill; + else + region_cb = &devlink_region_direct_fill; + region_cb_priv = region; + } else { + struct devlink_snapshot *snapshot; + u32 snapshot_id; + + if (nla_get_flag(attrs[DEVLINK_ATTR_REGION_DIRECT])) { + NL_SET_ERR_MSG_ATTR(cb->extack, snapshot_attr, "Direct region read does not use snapshot"); + err = -EINVAL; + goto out_unlock; + } + + snapshot_id = nla_get_u32(snapshot_attr); + snapshot = devlink_region_snapshot_get_by_id(region, snapshot_id); + if (!snapshot) { + NL_SET_ERR_MSG_ATTR(cb->extack, snapshot_attr, "Requested snapshot does not exist"); + err = -EINVAL; + goto out_unlock; + } + region_cb = &devlink_region_snapshot_fill; + region_cb_priv = snapshot; } if (attrs[DEVLINK_ATTR_REGION_CHUNK_ADDR] && @@ -6633,9 +6678,9 @@ static int devlink_nl_cmd_region_read_dumpit(struct sk_buff *skb, goto nla_put_failure; } - err = devlink_nl_region_read_fill(skb, &devlink_region_snapshot_fill, - snapshot, start_offset, end_offset, - &ret_offset, cb->extack); + err = devlink_nl_region_read_fill(skb, region_cb, region_cb_priv, + start_offset, end_offset, &ret_offset, + cb->extack); if (err && err != -EMSGSIZE) goto nla_put_failure; @@ -9280,6 +9325,7 @@ static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = { [DEVLINK_ATTR_SELFTESTS] = { .type = NLA_NESTED }, [DEVLINK_ATTR_RATE_TX_PRIORITY] = { .type = NLA_U32 }, [DEVLINK_ATTR_RATE_TX_WEIGHT] = { .type = NLA_U32 }, + [DEVLINK_ATTR_REGION_DIRECT] = { .type = NLA_FLAG }, }; static const struct genl_small_ops devlink_nl_ops[] = {