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 X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DDA0C433E6 for ; Thu, 14 Jan 2021 12:11:33 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D18E323A53 for ; Thu, 14 Jan 2021 12:11:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D18E323A53 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; 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Thu, 14 Jan 2021 12:11:27 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id o2BwheewQXtg for ; Thu, 14 Jan 2021 12:11:25 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by silver.osuosl.org (Postfix) with ESMTPS id CC51420110 for ; Thu, 14 Jan 2021 12:11:24 +0000 (UTC) Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DGjmm3wbLzMKPF; Thu, 14 Jan 2021 20:10:00 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Thu, 14 Jan 2021 20:11:09 +0800 Subject: Re: [PATCH 4/5] vfio/iommu_type1: Carefully use unmap_unpin_all during dirty tracking To: Alex Williamson References: <20210107092901.19712-1-zhukeqian1@huawei.com> <20210107092901.19712-5-zhukeqian1@huawei.com> <20210111144913.3092b1b1@omen.home.shazbot.org> <198f0afd-343a-9fbc-9556-95670ca76a2c@huawei.com> <20210112125331.789f47a5@omen.home.shazbot.org> From: Keqian Zhu Message-ID: <14ee2346-ea9e-ab24-40d7-45a3bd16510d@huawei.com> Date: Thu, 14 Jan 2021 20:11:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210112125331.789f47a5@omen.home.shazbot.org> X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Cc: Mark Rutland , jiangkunkun@huawei.com, kvm@vger.kernel.org, Catalin Marinas , Kirti Wankhede , Will Deacon , kvmarm@lists.cs.columbia.edu, Marc Zyngier , Daniel Lezcano , wanghaibin.wang@huawei.com, Julien Thierry , Suzuki K Poulose , Alexios Zavras , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Cornelia Huck , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, James Morse , Andrew Morton , Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 2021/1/13 3:53, Alex Williamson wrote: > On Tue, 12 Jan 2021 20:04:38 +0800 > Keqian Zhu wrote: > >> On 2021/1/12 5:49, Alex Williamson wrote: >>> On Thu, 7 Jan 2021 17:29:00 +0800 >>> Keqian Zhu wrote: >>> >>>> If we detach group during dirty page tracking, we shouldn't remove >>>> vfio_dma, because dirty log will lose. >>>> >>>> But we don't prevent unmap_unpin_all in vfio_iommu_release, because >>>> under normal procedure, dirty tracking has been stopped. >>> >>> This looks like it's creating a larger problem than it's fixing, it's >>> not our job to maintain the dirty bitmap regardless of what the user >>> does. If the user detaches the last group in a container causing the >>> mappings within that container to be deconstructed before the user has >>> collected dirty pages, that sounds like a user error. A container with >>> no groups is de-privileged and therefore loses all state. Thanks, >>> >>> Alex >> >> Hi Alex, >> >> This looks good to me ;-). That's a reasonable constraint for user behavior. >> >> What about replacing this patch with an addition to the uapi document of >> VFIO_GROUP_UNSET_CONTAINER? User should pay attention to this when call this >> ioctl during dirty tracking. > > Here's the current uapi comment: > > /** > * VFIO_GROUP_UNSET_CONTAINER - _IO(VFIO_TYPE, VFIO_BASE + 5) > * > * Remove the group from the attached container. This is the > * opposite of the SET_CONTAINER call and returns the group to > * an initial state. All device file descriptors must be released > * prior to calling this interface. When removing the last group > * from a container, the IOMMU will be disabled and all state lost, > * effectively also returning the VFIO file descriptor to an initial > * state. > * Return: 0 on success, -errno on failure. > * Availability: When attached to container > */ > > So we already indicate that "all state" of the container is lost when > removing the last group, I don't see that it's necessarily to > explicitly include dirty bitmap state beyond that statement. Without > mappings there can be no dirty bitmap to track. OK :-) . > > > And any comments on other patches? thanks. > > I had a difficult time mapping the commit log to the actual code > change, I'll likely have some wording suggestions. Is patch 5/5 still > necessary if this patch is dropped? Thanks, > I think the 5th patch is still necessary. vfio_sanity_check_pfn_list() is used to check whether pfn_list of vfio_dma is empty. but we apply this check just for external domain. If the iommu backed domain also pin some pages, then this check fails. So I think we should use this check only when all domains are about to be removed. Besides, this patch should extract the "WARN_ON(iommu->notifier.head);" just for external domain. Thanks, Keqian > Alex > >>>> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking") >>>> Signed-off-by: Keqian Zhu >>>> --- >>>> drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++-- >>>> 1 file changed, 12 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >>>> index 26b7eb2a5cfc..9776a059904d 100644 >>>> --- a/drivers/vfio/vfio_iommu_type1.c >>>> +++ b/drivers/vfio/vfio_iommu_type1.c >>>> @@ -2373,7 +2373,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> if (list_empty(&iommu->external_domain->group_list)) { >>>> vfio_sanity_check_pfn_list(iommu); >>>> >>>> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) >>>> + /* >>>> + * During dirty page tracking, we can't remove >>>> + * vfio_dma because dirty log will lose. >>>> + */ >>>> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> >>>> kfree(iommu->external_domain); >>>> @@ -2406,10 +2411,15 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> * iommu and external domain doesn't exist, then all the >>>> * mappings go away too. If it's the last domain with iommu and >>>> * external domain exist, update accounting >>>> + * >>>> + * Note: During dirty page tracking, we can't remove vfio_dma >>>> + * because dirty log will lose. Just update accounting is a good >>>> + * choice. >>>> */ >>>> if (list_empty(&domain->group_list)) { >>>> if (list_is_singular(&iommu->domain_list)) { >>>> - if (!iommu->external_domain) >>>> + if (!iommu->external_domain && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> else >>>> vfio_iommu_unmap_unpin_reaccount(iommu); >>> >>> . >>> >> > > . > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu 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 X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 702E9C433E0 for ; Thu, 14 Jan 2021 12:11:31 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id A418F23A52 for ; Thu, 14 Jan 2021 12:11:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A418F23A52 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D2F9C4B1B9; Thu, 14 Jan 2021 07:11:29 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id dLQ7xyfv3yrM; Thu, 14 Jan 2021 07:11:28 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8505A4B1B6; Thu, 14 Jan 2021 07:11:28 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 36A864B1A1 for ; Thu, 14 Jan 2021 07:11:27 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jN7ZdiG067PY for ; Thu, 14 Jan 2021 07:11:25 -0500 (EST) Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 7E3EC4B1B4 for ; Thu, 14 Jan 2021 07:11:24 -0500 (EST) Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DGjmm3wbLzMKPF; Thu, 14 Jan 2021 20:10:00 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Thu, 14 Jan 2021 20:11:09 +0800 Subject: Re: [PATCH 4/5] vfio/iommu_type1: Carefully use unmap_unpin_all during dirty tracking To: Alex Williamson References: <20210107092901.19712-1-zhukeqian1@huawei.com> <20210107092901.19712-5-zhukeqian1@huawei.com> <20210111144913.3092b1b1@omen.home.shazbot.org> <198f0afd-343a-9fbc-9556-95670ca76a2c@huawei.com> <20210112125331.789f47a5@omen.home.shazbot.org> From: Keqian Zhu Message-ID: <14ee2346-ea9e-ab24-40d7-45a3bd16510d@huawei.com> Date: Thu, 14 Jan 2021 20:11:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210112125331.789f47a5@omen.home.shazbot.org> X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Cc: kvm@vger.kernel.org, Catalin Marinas , Kirti Wankhede , Will Deacon , kvmarm@lists.cs.columbia.edu, Marc Zyngier , Joerg Roedel , Daniel Lezcano , Alexios Zavras , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Cornelia Huck , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Andrew Morton , Robin Murphy X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 2021/1/13 3:53, Alex Williamson wrote: > On Tue, 12 Jan 2021 20:04:38 +0800 > Keqian Zhu wrote: > >> On 2021/1/12 5:49, Alex Williamson wrote: >>> On Thu, 7 Jan 2021 17:29:00 +0800 >>> Keqian Zhu wrote: >>> >>>> If we detach group during dirty page tracking, we shouldn't remove >>>> vfio_dma, because dirty log will lose. >>>> >>>> But we don't prevent unmap_unpin_all in vfio_iommu_release, because >>>> under normal procedure, dirty tracking has been stopped. >>> >>> This looks like it's creating a larger problem than it's fixing, it's >>> not our job to maintain the dirty bitmap regardless of what the user >>> does. If the user detaches the last group in a container causing the >>> mappings within that container to be deconstructed before the user has >>> collected dirty pages, that sounds like a user error. A container with >>> no groups is de-privileged and therefore loses all state. Thanks, >>> >>> Alex >> >> Hi Alex, >> >> This looks good to me ;-). That's a reasonable constraint for user behavior. >> >> What about replacing this patch with an addition to the uapi document of >> VFIO_GROUP_UNSET_CONTAINER? User should pay attention to this when call this >> ioctl during dirty tracking. > > Here's the current uapi comment: > > /** > * VFIO_GROUP_UNSET_CONTAINER - _IO(VFIO_TYPE, VFIO_BASE + 5) > * > * Remove the group from the attached container. This is the > * opposite of the SET_CONTAINER call and returns the group to > * an initial state. All device file descriptors must be released > * prior to calling this interface. When removing the last group > * from a container, the IOMMU will be disabled and all state lost, > * effectively also returning the VFIO file descriptor to an initial > * state. > * Return: 0 on success, -errno on failure. > * Availability: When attached to container > */ > > So we already indicate that "all state" of the container is lost when > removing the last group, I don't see that it's necessarily to > explicitly include dirty bitmap state beyond that statement. Without > mappings there can be no dirty bitmap to track. OK :-) . > > > And any comments on other patches? thanks. > > I had a difficult time mapping the commit log to the actual code > change, I'll likely have some wording suggestions. Is patch 5/5 still > necessary if this patch is dropped? Thanks, > I think the 5th patch is still necessary. vfio_sanity_check_pfn_list() is used to check whether pfn_list of vfio_dma is empty. but we apply this check just for external domain. If the iommu backed domain also pin some pages, then this check fails. So I think we should use this check only when all domains are about to be removed. Besides, this patch should extract the "WARN_ON(iommu->notifier.head);" just for external domain. Thanks, Keqian > Alex > >>>> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking") >>>> Signed-off-by: Keqian Zhu >>>> --- >>>> drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++-- >>>> 1 file changed, 12 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >>>> index 26b7eb2a5cfc..9776a059904d 100644 >>>> --- a/drivers/vfio/vfio_iommu_type1.c >>>> +++ b/drivers/vfio/vfio_iommu_type1.c >>>> @@ -2373,7 +2373,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> if (list_empty(&iommu->external_domain->group_list)) { >>>> vfio_sanity_check_pfn_list(iommu); >>>> >>>> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) >>>> + /* >>>> + * During dirty page tracking, we can't remove >>>> + * vfio_dma because dirty log will lose. >>>> + */ >>>> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> >>>> kfree(iommu->external_domain); >>>> @@ -2406,10 +2411,15 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> * iommu and external domain doesn't exist, then all the >>>> * mappings go away too. If it's the last domain with iommu and >>>> * external domain exist, update accounting >>>> + * >>>> + * Note: During dirty page tracking, we can't remove vfio_dma >>>> + * because dirty log will lose. Just update accounting is a good >>>> + * choice. >>>> */ >>>> if (list_empty(&domain->group_list)) { >>>> if (list_is_singular(&iommu->domain_list)) { >>>> - if (!iommu->external_domain) >>>> + if (!iommu->external_domain && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> else >>>> vfio_iommu_unmap_unpin_reaccount(iommu); >>> >>> . >>> >> > > . > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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 X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22502C433E0 for ; Thu, 14 Jan 2021 12:12:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BD4D423A53 for ; Thu, 14 Jan 2021 12:12:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728146AbhANMMD (ORCPT ); Thu, 14 Jan 2021 07:12:03 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:11099 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726427AbhANMMD (ORCPT ); Thu, 14 Jan 2021 07:12:03 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DGjmm3wbLzMKPF; Thu, 14 Jan 2021 20:10:00 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Thu, 14 Jan 2021 20:11:09 +0800 Subject: Re: [PATCH 4/5] vfio/iommu_type1: Carefully use unmap_unpin_all during dirty tracking To: Alex Williamson References: <20210107092901.19712-1-zhukeqian1@huawei.com> <20210107092901.19712-5-zhukeqian1@huawei.com> <20210111144913.3092b1b1@omen.home.shazbot.org> <198f0afd-343a-9fbc-9556-95670ca76a2c@huawei.com> <20210112125331.789f47a5@omen.home.shazbot.org> CC: , , , , , Kirti Wankhede , Cornelia Huck , Will Deacon , "Marc Zyngier" , Catalin Marinas , "Mark Rutland" , James Morse , "Robin Murphy" , Joerg Roedel , Daniel Lezcano , Thomas Gleixner , "Suzuki K Poulose" , Julien Thierry , Andrew Morton , Alexios Zavras , , From: Keqian Zhu Message-ID: <14ee2346-ea9e-ab24-40d7-45a3bd16510d@huawei.com> Date: Thu, 14 Jan 2021 20:11:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210112125331.789f47a5@omen.home.shazbot.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/1/13 3:53, Alex Williamson wrote: > On Tue, 12 Jan 2021 20:04:38 +0800 > Keqian Zhu wrote: > >> On 2021/1/12 5:49, Alex Williamson wrote: >>> On Thu, 7 Jan 2021 17:29:00 +0800 >>> Keqian Zhu wrote: >>> >>>> If we detach group during dirty page tracking, we shouldn't remove >>>> vfio_dma, because dirty log will lose. >>>> >>>> But we don't prevent unmap_unpin_all in vfio_iommu_release, because >>>> under normal procedure, dirty tracking has been stopped. >>> >>> This looks like it's creating a larger problem than it's fixing, it's >>> not our job to maintain the dirty bitmap regardless of what the user >>> does. If the user detaches the last group in a container causing the >>> mappings within that container to be deconstructed before the user has >>> collected dirty pages, that sounds like a user error. A container with >>> no groups is de-privileged and therefore loses all state. Thanks, >>> >>> Alex >> >> Hi Alex, >> >> This looks good to me ;-). That's a reasonable constraint for user behavior. >> >> What about replacing this patch with an addition to the uapi document of >> VFIO_GROUP_UNSET_CONTAINER? User should pay attention to this when call this >> ioctl during dirty tracking. > > Here's the current uapi comment: > > /** > * VFIO_GROUP_UNSET_CONTAINER - _IO(VFIO_TYPE, VFIO_BASE + 5) > * > * Remove the group from the attached container. This is the > * opposite of the SET_CONTAINER call and returns the group to > * an initial state. All device file descriptors must be released > * prior to calling this interface. When removing the last group > * from a container, the IOMMU will be disabled and all state lost, > * effectively also returning the VFIO file descriptor to an initial > * state. > * Return: 0 on success, -errno on failure. > * Availability: When attached to container > */ > > So we already indicate that "all state" of the container is lost when > removing the last group, I don't see that it's necessarily to > explicitly include dirty bitmap state beyond that statement. Without > mappings there can be no dirty bitmap to track. OK :-) . > > > And any comments on other patches? thanks. > > I had a difficult time mapping the commit log to the actual code > change, I'll likely have some wording suggestions. Is patch 5/5 still > necessary if this patch is dropped? Thanks, > I think the 5th patch is still necessary. vfio_sanity_check_pfn_list() is used to check whether pfn_list of vfio_dma is empty. but we apply this check just for external domain. If the iommu backed domain also pin some pages, then this check fails. So I think we should use this check only when all domains are about to be removed. Besides, this patch should extract the "WARN_ON(iommu->notifier.head);" just for external domain. Thanks, Keqian > Alex > >>>> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking") >>>> Signed-off-by: Keqian Zhu >>>> --- >>>> drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++-- >>>> 1 file changed, 12 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >>>> index 26b7eb2a5cfc..9776a059904d 100644 >>>> --- a/drivers/vfio/vfio_iommu_type1.c >>>> +++ b/drivers/vfio/vfio_iommu_type1.c >>>> @@ -2373,7 +2373,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> if (list_empty(&iommu->external_domain->group_list)) { >>>> vfio_sanity_check_pfn_list(iommu); >>>> >>>> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) >>>> + /* >>>> + * During dirty page tracking, we can't remove >>>> + * vfio_dma because dirty log will lose. >>>> + */ >>>> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> >>>> kfree(iommu->external_domain); >>>> @@ -2406,10 +2411,15 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> * iommu and external domain doesn't exist, then all the >>>> * mappings go away too. If it's the last domain with iommu and >>>> * external domain exist, update accounting >>>> + * >>>> + * Note: During dirty page tracking, we can't remove vfio_dma >>>> + * because dirty log will lose. Just update accounting is a good >>>> + * choice. >>>> */ >>>> if (list_empty(&domain->group_list)) { >>>> if (list_is_singular(&iommu->domain_list)) { >>>> - if (!iommu->external_domain) >>>> + if (!iommu->external_domain && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> else >>>> vfio_iommu_unmap_unpin_reaccount(iommu); >>> >>> . >>> >> > > . > 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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F090AC433E0 for ; Thu, 14 Jan 2021 12:13:42 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A02F223A52 for ; 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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l01UF-0006fA-Oh; Thu, 14 Jan 2021 12:12:23 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l01UD-0006YO-4c for linux-arm-kernel@lists.infradead.org; Thu, 14 Jan 2021 12:12:22 +0000 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DGjmm3wbLzMKPF; Thu, 14 Jan 2021 20:10:00 +0800 (CST) Received: from [10.174.184.42] (10.174.184.42) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Thu, 14 Jan 2021 20:11:09 +0800 Subject: Re: [PATCH 4/5] vfio/iommu_type1: Carefully use unmap_unpin_all during dirty tracking To: Alex Williamson References: <20210107092901.19712-1-zhukeqian1@huawei.com> <20210107092901.19712-5-zhukeqian1@huawei.com> <20210111144913.3092b1b1@omen.home.shazbot.org> <198f0afd-343a-9fbc-9556-95670ca76a2c@huawei.com> <20210112125331.789f47a5@omen.home.shazbot.org> From: Keqian Zhu Message-ID: <14ee2346-ea9e-ab24-40d7-45a3bd16510d@huawei.com> Date: Thu, 14 Jan 2021 20:11:00 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20210112125331.789f47a5@omen.home.shazbot.org> X-Originating-IP: [10.174.184.42] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210114_071221_727010_78A6B4D7 X-CRM114-Status: GOOD ( 27.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , jiangkunkun@huawei.com, kvm@vger.kernel.org, Catalin Marinas , Kirti Wankhede , Will Deacon , kvmarm@lists.cs.columbia.edu, Marc Zyngier , Joerg Roedel , Daniel Lezcano , wanghaibin.wang@huawei.com, Julien Thierry , Suzuki K Poulose , Alexios Zavras , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Cornelia Huck , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, James Morse , Andrew Morton , Robin Murphy Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2021/1/13 3:53, Alex Williamson wrote: > On Tue, 12 Jan 2021 20:04:38 +0800 > Keqian Zhu wrote: > >> On 2021/1/12 5:49, Alex Williamson wrote: >>> On Thu, 7 Jan 2021 17:29:00 +0800 >>> Keqian Zhu wrote: >>> >>>> If we detach group during dirty page tracking, we shouldn't remove >>>> vfio_dma, because dirty log will lose. >>>> >>>> But we don't prevent unmap_unpin_all in vfio_iommu_release, because >>>> under normal procedure, dirty tracking has been stopped. >>> >>> This looks like it's creating a larger problem than it's fixing, it's >>> not our job to maintain the dirty bitmap regardless of what the user >>> does. If the user detaches the last group in a container causing the >>> mappings within that container to be deconstructed before the user has >>> collected dirty pages, that sounds like a user error. A container with >>> no groups is de-privileged and therefore loses all state. Thanks, >>> >>> Alex >> >> Hi Alex, >> >> This looks good to me ;-). That's a reasonable constraint for user behavior. >> >> What about replacing this patch with an addition to the uapi document of >> VFIO_GROUP_UNSET_CONTAINER? User should pay attention to this when call this >> ioctl during dirty tracking. > > Here's the current uapi comment: > > /** > * VFIO_GROUP_UNSET_CONTAINER - _IO(VFIO_TYPE, VFIO_BASE + 5) > * > * Remove the group from the attached container. This is the > * opposite of the SET_CONTAINER call and returns the group to > * an initial state. All device file descriptors must be released > * prior to calling this interface. When removing the last group > * from a container, the IOMMU will be disabled and all state lost, > * effectively also returning the VFIO file descriptor to an initial > * state. > * Return: 0 on success, -errno on failure. > * Availability: When attached to container > */ > > So we already indicate that "all state" of the container is lost when > removing the last group, I don't see that it's necessarily to > explicitly include dirty bitmap state beyond that statement. Without > mappings there can be no dirty bitmap to track. OK :-) . > > > And any comments on other patches? thanks. > > I had a difficult time mapping the commit log to the actual code > change, I'll likely have some wording suggestions. Is patch 5/5 still > necessary if this patch is dropped? Thanks, > I think the 5th patch is still necessary. vfio_sanity_check_pfn_list() is used to check whether pfn_list of vfio_dma is empty. but we apply this check just for external domain. If the iommu backed domain also pin some pages, then this check fails. So I think we should use this check only when all domains are about to be removed. Besides, this patch should extract the "WARN_ON(iommu->notifier.head);" just for external domain. Thanks, Keqian > Alex > >>>> Fixes: d6a4c185660c ("vfio iommu: Implementation of ioctl for dirty pages tracking") >>>> Signed-off-by: Keqian Zhu >>>> --- >>>> drivers/vfio/vfio_iommu_type1.c | 14 ++++++++++++-- >>>> 1 file changed, 12 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >>>> index 26b7eb2a5cfc..9776a059904d 100644 >>>> --- a/drivers/vfio/vfio_iommu_type1.c >>>> +++ b/drivers/vfio/vfio_iommu_type1.c >>>> @@ -2373,7 +2373,12 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> if (list_empty(&iommu->external_domain->group_list)) { >>>> vfio_sanity_check_pfn_list(iommu); >>>> >>>> - if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)) >>>> + /* >>>> + * During dirty page tracking, we can't remove >>>> + * vfio_dma because dirty log will lose. >>>> + */ >>>> + if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu) && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> >>>> kfree(iommu->external_domain); >>>> @@ -2406,10 +2411,15 @@ static void vfio_iommu_type1_detach_group(void *iommu_data, >>>> * iommu and external domain doesn't exist, then all the >>>> * mappings go away too. If it's the last domain with iommu and >>>> * external domain exist, update accounting >>>> + * >>>> + * Note: During dirty page tracking, we can't remove vfio_dma >>>> + * because dirty log will lose. Just update accounting is a good >>>> + * choice. >>>> */ >>>> if (list_empty(&domain->group_list)) { >>>> if (list_is_singular(&iommu->domain_list)) { >>>> - if (!iommu->external_domain) >>>> + if (!iommu->external_domain && >>>> + !iommu->dirty_page_tracking) >>>> vfio_iommu_unmap_unpin_all(iommu); >>>> else >>>> vfio_iommu_unmap_unpin_reaccount(iommu); >>> >>> . >>> >> > > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel