From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout02.his.huawei.com (canpmsgout02.his.huawei.com [113.46.200.217]) (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 086F3271454 for ; Sat, 18 Oct 2025 10:39:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.217 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760783984; cv=none; b=eGEuT+LvNSQ1hYEIJvh+WS49vCZp9K0mCU7LsmHFAV5qX1ClvcNqveTOCdVvkGi25XR5/+3dFOxj4YcLXhgOXHtdJgpeuKBZM4w2s6QqmUqrYCSWYpPDuEV9fsswK/yRPSH4KHp3xfV+Lo0nDZFZ/FPftQ4IML1QmNdCTrsSefE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760783984; c=relaxed/simple; bh=MkcNgvKvjSSG00mhcQ2qY/2MHLWrUUqHCKHhm5JHgwg=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=J9B5bgArvgWVVLQPOPkMSRlNtFSfXO4lbSJGH0WKXqo6rps9+8IEOgE2AoMfdL5/JLQopBg915qLtL1QVmHAKcUX+dgxItExziy04MohjDzb63wQpylITHcAufz7jYzIK1hcr+d9Ii8D3pvkfn8lWizKzkb6Zl9reKcDp4YwxDw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=Dh7p0h6c; arc=none smtp.client-ip=113.46.200.217 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="Dh7p0h6c" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=f+51DM99CEdSFDPj0ZKr0xiXs9AF5iALomLseFpeJs8=; b=Dh7p0h6ckcL1ZyDbAEAtZheChwQS6K8kQGdngk43Q4CA/ahRus3uQRF8JvXdkvLtbx7fuh6AH kFQDQFjiPNvy2ZqGHWGWln9eFQ7iI0xRts2OqA/rzKhTxTwB6vXYgx/XCY+FqDKFoKMjUsfOFMt JZSW+6SMJTSU73JqutAIizE= Received: from mail.maildlp.com (unknown [172.19.163.174]) by canpmsgout02.his.huawei.com (SkyGuard) with ESMTPS id 4cpdT75xGyzcZyL; Sat, 18 Oct 2025 18:38:35 +0800 (CST) Received: from kwepemj200003.china.huawei.com (unknown [7.202.194.15]) by mail.maildlp.com (Postfix) with ESMTPS id B5A0E14010D; Sat, 18 Oct 2025 18:39:39 +0800 (CST) Received: from [10.67.120.170] (10.67.120.170) by kwepemj200003.china.huawei.com (7.202.194.15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Sat, 18 Oct 2025 18:39:39 +0800 Message-ID: Date: Sat, 18 Oct 2025 18:39:38 +0800 Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/2] iommu: Add io_ptdump debug interface for iommu To: Jason Gunthorpe CC: , , , , , , , , , , , References: <20250814093005.2040511-1-xiaqinxin@huawei.com> <20250902161028.GC184112@ziepe.ca> <20250910141547.GD882933@ziepe.ca> <20250915162810.GI882933@ziepe.ca> From: Qinxin Xia In-Reply-To: <20250915162810.GI882933@ziepe.ca> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To kwepemj200003.china.huawei.com (7.202.194.15) On 2025/9/16 00:28:10, Jason Gunthorpe wrote: > On Thu, Sep 11, 2025 at 10:08:55PM +0800, Qinxin Xia wrote: >> >> >> On 2025/9/10 22:15:47, Jason Gunthorpe wrote: >>> On Wed, Sep 10, 2025 at 11:20:08AM +0800, Qinxin Xia wrote: >>>> Ok, I see, my colleague Wang Zhou also released a version of io_ptdump >>>> a long time ago, which is implemented in smmu debugfs. Will recommends that >>>> io_ptdump be implemented in a way similar to CPU page table dump. Using >>>> debugfs to expose the data and using format-specific callbacks to implement >>>> specific data dumps, I'll talk to him about this as well. >>> >>> I feel we should have a iommu subsystem debugfs and per-iommu_domain >>> directories to dump the page tables. >>> >>> The smmu debugfs can report what iommu_domains each STE/CD is >>> referencing. >>> >>> This also needs RCU freeing of page table levels as a locking >>> strategy. >> >> Thanks, I'll add RCU in the next version, but there's some >> confusion, > > Please don't, RCU is quite complicated, I don't really want to see > attempts to retrofit it into the existing page table code. This is why > I've said debugging like this needs to go along with the new iommu pt > work to consolidate the page table code. > >> Do you >> mean to create a directory for each domain? like： >> >> /sys/kernel/debug/io_page_tables/domain_xxxx (xxxx=domain addr) > > Something like this could be a reasonable option. > >> tree domain_xxxx like: >> domain_xxxx >> └── group x >> │ └── device > > Though I would probably not include this information.. > Users could be difficult to map domain to devices, so I think maybe we should provide the device information contained in the domain.>> └── DebugFS file: /sys/kernel/debug/io_page_tables >> └── Operation: Reading this file triggers the entire debug information >> collection process > > I don't think we want to dump every page table in the system in one > file. > >> Do you mean that the interface in io-pgtable-arm.c is directly invoked >> during the process of obtaining page table information without passing >> through arm-smmu-v3.c? > > Yes, this is what iommu pt brings. > > Jason