From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80AA8281532; Sat, 8 Aug 2026 01:19:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786151958; cv=none; b=AJP7cAtSQIn3vh5DdargHlMROzZapnoRQA0h3aervcOLZx1uHZ6/43wZway/bB+3glrPYzKyCaS6iRnMWzDcHdZ7HoQ5iJrdtQC6LujhxsH07w/xbflTKubkPxGhFW0OhH9qjZiapzUU4OL5+sHww7hcRyOkfjDCOaT7wla43Iw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786151958; c=relaxed/simple; bh=i7/GPv0zwtNRHmtbqpbp+cRuAUyXry6ImUnI8sVbomk=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aGWAzzidBa9xcuyI9dl3GNjUFFJ2Cwg5tBGYBCvRRuKW3WIjVGXDkxFJSt3R6TnvHcZXKTkx1i84vC3aM+mQAZbCfv7la7L1oyT6QHHR/8QhvsJDJOkZ8rruMgxNiAFCZUjfCknuZxCZyB8EMnArMRUUJ9uBZVPEYoEpts7A4Zk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=n1XJ1AHI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="n1XJ1AHI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0CB261F000E9; Sat, 8 Aug 2026 01:19:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786151957; bh=en2inzUc+Bz/LksaPJcN/DhNmRyA0fDxj7oEZ5Gmly0=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=n1XJ1AHIdMdj4w2zMKMJV6yYsrlrYHdOPWi4I54j3E12dyfWMlB/2szMM1pUYS9dY ERQI6bHBgwHfGr9d9D4PPH2/jBRv80M7hd9UD3ypScVGCxRPvpklxX/bvJbZAxAObe HDXUX7Mykl/t9GAwOkCOGEqiEMLKWpeS96tRsgKvjA187pjzgO1szkG/mB8jZfyuhx KQ+M/drB3tGtbu0/P2Uhnnu7c4Ge7YKn5YINWXIm5c5LZAPsyfN9kC47IKqX1jKL5F pjvgv4yc4uGvubPS2/TfdYPbk/0wo9xVyLRALXa/bOJryDNc7eb1Z72E/FcXNeZBhh hflkWmjNy4kPg== Date: Fri, 7 Aug 2026 18:19:16 -0700 From: Jakub Kicinski To: Xiong Weimin Cc: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?UTF-8?B?UMOpcmV6?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] virtio_net: roll back RSS state on control failure Message-ID: <20260807181916.63395d4f@kernel.org> In-Reply-To: <20260804073654.1293243-1-xiongweimin@kylinos.cn> References: <20260804073654.1293243-1-xiongweimin@kylinos.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 4 Aug 2026 15:36:54 +0800 Xiong Weimin wrote: > The ethtool RSS and RXHASH paths update the driver's cached RSS state > before committing the change to the device. If the control virtqueue > command fails, the cached hash types, key or indirection table can then > report a configuration that the device did not accept. > > Preserve the previous local state around RSS/hash control commands and > restore it when the device update fails, while propagating the error to > the caller. I guess.. saving the data and then copying it back doesn't seem super clean but I guess since we DMA directly from the info struct.. Michael, Jason, looks okay? > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 3e2a5876c..ccd96315a 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -4295,6 +4295,7 @@ static int virtnet_set_hashflow(struct net_device *dev, > struct netlink_ext_ack *extack) > { > struct virtnet_info *vi = netdev_priv(dev); > + u32 old_hashtypes = vi->rss_hash_types_saved; > u32 new_hashtypes = vi->rss_hash_types_saved; > bool is_disable = info->data & RXH_DISCARD; > bool is_l4 = info->data == (RXH_IP_SRC | RXH_IP_DST | RXH_L4_B_0_1 | RXH_L4_B_2_3); > @@ -4350,9 +4351,13 @@ static int virtnet_set_hashflow(struct net_device *dev, > if (new_hashtypes != vi->rss_hash_types_saved) { > vi->rss_hash_types_saved = new_hashtypes; > vi->rss_hdr->hash_types = cpu_to_le32(vi->rss_hash_types_saved); > - if (vi->dev->features & NETIF_F_RXHASH) > - if (!virtnet_commit_rss_command(vi)) > + if (vi->dev->features & NETIF_F_RXHASH) { > + if (!virtnet_commit_rss_command(vi)) { > + vi->rss_hash_types_saved = old_hashtypes; > + vi->rss_hdr->hash_types = cpu_to_le32(old_hashtypes); > return -EINVAL; > + } > + } > } > > return 0; > @@ -5546,6 +5551,8 @@ static int virtnet_set_rxfh(struct net_device *dev, > struct netlink_ext_ack *extack) > { > struct virtnet_info *vi = netdev_priv(dev); > + struct virtio_net_rss_config_hdr *old_rss_hdr = NULL; > + u8 old_rss_key[NETDEV_RSS_KEY_LEN]; > bool update = false; > int i; > > @@ -5553,14 +5560,8 @@ static int virtnet_set_rxfh(struct net_device *dev, > rxfh->hfunc != ETH_RSS_HASH_TOP) > return -EOPNOTSUPP; > > - if (rxfh->indir) { > - if (!vi->has_rss) > - return -EOPNOTSUPP; > - > - for (i = 0; i < vi->rss_indir_table_size; ++i) > - vi->rss_hdr->indirection_table[i] = cpu_to_le16(rxfh->indir[i]); > - update = true; > - } > + if (rxfh->indir && !vi->has_rss) > + return -EOPNOTSUPP; > > if (rxfh->key) { > /* If either _F_HASH_REPORT or _F_RSS are negotiated, the > @@ -5569,13 +5570,36 @@ static int virtnet_set_rxfh(struct net_device *dev, > */ > if (!vi->has_rss && !vi->has_rss_hash_report) > return -EOPNOTSUPP; > + } > + > + if (rxfh->indir) { > + old_rss_hdr = kmemdup(vi->rss_hdr, virtnet_rss_hdr_size(vi), > + GFP_KERNEL); > + if (!old_rss_hdr) > + return -ENOMEM; > + > + for (i = 0; i < vi->rss_indir_table_size; ++i) > + vi->rss_hdr->indirection_table[i] = > + cpu_to_le16(rxfh->indir[i]); > + update = true; > + } > > + if (rxfh->key) { > + memcpy(old_rss_key, vi->rss_hash_key_data, vi->rss_key_size); > memcpy(vi->rss_hash_key_data, rxfh->key, vi->rss_key_size); > update = true; > } > > - if (update) > - virtnet_commit_rss_command(vi); > + if (update && !virtnet_commit_rss_command(vi)) { > + if (old_rss_hdr) > + memcpy(vi->rss_hdr, old_rss_hdr, virtnet_rss_hdr_size(vi)); > + if (rxfh->key) > + memcpy(vi->rss_hash_key_data, old_rss_key, vi->rss_key_size); > + kfree(old_rss_hdr); > + return -EINVAL; > + } > + > + kfree(old_rss_hdr); > > return 0; > } > @@ -6171,13 +6195,17 @@ static int virtnet_set_features(struct net_device *dev, > } > > if ((dev->features ^ features) & NETIF_F_RXHASH) { > + __le32 hash_types = vi->rss_hdr->hash_types; > + > if (features & NETIF_F_RXHASH) > vi->rss_hdr->hash_types = cpu_to_le32(vi->rss_hash_types_saved); > else > vi->rss_hdr->hash_types = cpu_to_le32(VIRTIO_NET_HASH_REPORT_NONE); > > - if (!virtnet_commit_rss_command(vi)) > + if (!virtnet_commit_rss_command(vi)) { > + vi->rss_hdr->hash_types = hash_types; > return -EINVAL; > + } > } > > return 0;