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 5ABDDC636CC for ; Thu, 16 Feb 2023 00:44:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229572AbjBPAon (ORCPT ); Wed, 15 Feb 2023 19:44:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229546AbjBPAoj (ORCPT ); Wed, 15 Feb 2023 19:44:39 -0500 Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E393842DF4 for ; Wed, 15 Feb 2023 16:44:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1676508278; x=1708044278; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=H9B37YND2PlxQzaqANv6jo0wgH3eFakVkiI7KDSHJJI=; b=fcUipCEZ3aGbheTN4fiP37n79jBakQmqJzNnxw8KiJrpufbQFro5J++S N6gZALVCzR0Jd/VlvcimGh9eoIeTw3vxN8CjkpSiezhbrWn+a7ZrUdbfW F6Y9wGfDv9txSvgiiigxosgUw5fXjXXhi88yyKNjjM8PJirAPiF5RwBtt NN93Rb/0IqylFWDeOb5f6rwmHZNB/3qPAxLMHHuYwh0UcI+tvbPiizxtA bUO98wb0CvKCDZJdxHGhdjkBN5MvXSzPCJW2qlUV/87mk7C9kePcLXWXV 7SO14LfZ74BByeCXdNSxkeGln2X92q7mp8aMq899QtF43ZB8aOgrRA4N8 w==; X-IronPort-AV: E=McAfee;i="6500,9779,10622"; a="311213609" X-IronPort-AV: E=Sophos;i="5.97,301,1669104000"; d="scan'208";a="311213609" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Feb 2023 16:44:38 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10622"; a="647469372" X-IronPort-AV: E=Sophos;i="5.97,301,1669104000"; d="scan'208";a="647469372" Received: from allen-box.sh.intel.com (HELO [10.239.159.48]) ([10.239.159.48]) by orsmga006.jf.intel.com with ESMTP; 15 Feb 2023 16:44:35 -0800 Message-ID: Date: Thu, 16 Feb 2023 08:36:12 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Cc: baolu.lu@linux.intel.com, iommu@lists.linux.dev, Joerg Roedel , Christoph Hellwig , Kevin Tian , Will Deacon , Robin Murphy , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] iommu: Use group ownership to avoid driver attachment Content-Language: en-US To: Jason Gunthorpe References: <20230213074941.919324-1-baolu.lu@linux.intel.com> <20230213074941.919324-3-baolu.lu@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/15/23 8:56 PM, Jason Gunthorpe wrote: > On Wed, Feb 15, 2023 at 01:51:14PM +0800, Baolu Lu wrote: >> On 2/13/23 10:19 PM, Jason Gunthorpe wrote: >>> On Mon, Feb 13, 2023 at 03:49:39PM +0800, Lu Baolu wrote: >>>> The iommu_group_store_type() requires the devices in the iommu group are >>>> not bound to any device driver during the whole operation. The existing >>>> code locks the device with device_lock(dev) and use device_is_bound() to >>>> check whether any driver is bound to device. >>>> >>>> In fact, this can be achieved through the DMA ownership helpers. Replace >>>> them with iommu_group_claim/release_dma_owner() helpers. >>>> >>>> Signed-off-by: Lu Baolu >>>> --- >>>> drivers/iommu/iommu.c | 27 +++++++++++++-------------- >>>> 1 file changed, 13 insertions(+), 14 deletions(-) >>>> >>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >>>> index 4f71dcd2621b..6547cb38480c 100644 >>>> --- a/drivers/iommu/iommu.c >>>> +++ b/drivers/iommu/iommu.c >>>> @@ -2807,12 +2807,6 @@ static int iommu_change_dev_def_domain(struct iommu_group *group, >>>> mutex_lock(&group->mutex); >>>> - if (group->default_domain != group->domain) { >>>> - dev_err_ratelimited(prev_dev, "Group not assigned to default domain\n"); >>>> - ret = -EBUSY; >>>> - goto out; >>>> - } >>>> - >>>> /* >>>> * iommu group wasn't locked while acquiring device lock in >>>> * iommu_group_store_type(). So, make sure that the device count hasn't >>>> @@ -2971,6 +2965,7 @@ static void iommu_group_unfreeze_dev_ops(struct iommu_group *group) >>>> static ssize_t iommu_group_store_type(struct iommu_group *group, >>>> const char *buf, size_t count) >>>> { >>>> + bool group_owner_claimed = false; >>>> struct group_device *grp_dev; >>>> struct device *dev; >>>> int ret, req_type; >>>> @@ -2992,6 +2987,14 @@ static ssize_t iommu_group_store_type(struct iommu_group *group, >>>> else >>>> return -EINVAL; >>>> + if (req_type != IOMMU_DOMAIN_DMA_FQ || >>>> + group->default_domain->type != IOMMU_DOMAIN_DMA) { >>>> + ret = iommu_group_claim_dma_owner(group, (void *)buf); >>>> + if (ret) >>>> + return ret; >>>> + group_owner_claimed = true; >>>> + } >>> I don't get it, this should be done unconditionally. If we couldn't >>> take ownership then we simply can't progress. >> The existing code allows the user to switch the default domain from >> strict to lazy invalidation mode. The default domain is not changed, >> hence it should be seamless and transparent to the device driver. > So make that a special case, get the group lock check if it is this > case and then just adjust it and exit, otherwise get ownership under > the group lock as discussed. OK. Will do like this in the next version. Best regards, baolu