From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-98.freemail.mail.aliyun.com (out30-98.freemail.mail.aliyun.com [115.124.30.98]) (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 190BF311968; Tue, 5 May 2026 13:48:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.98 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777988937; cv=none; b=dOpGiADbyruM0KgrSx5/rG69fonSC9xYyWEBikUIBC9B67LUDjcX/tHMWTrIXzO2XmNRz6u6pUV0P4CMDxCP7+2ycZJ6N85lN9nyfjimJUwDe+m+KHiNIrS5GtjDdDf/SjMs3JWLL+AJL5GtQVibLJEvAXUrW2ghS3FxiNOG7p8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777988937; c=relaxed/simple; bh=Zk/1K+MnMpA92ul7kl0jDIMKnTfYzSHa9pyZmtvAxfU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=g0i4DmXUHrAr+kLO7W7cVsO7BL+99V6UDuUzBzoV50y1iqdVgq/3mhu+CX+5sfE0nHlvLLzTiBUIsZDjEBsDhUFg87H+hf47dToij9qsVZbNxC5LJj8Q38RRNKlUCdOXUT9vOXGXfVP4oNiAYY8A+o9EOWbyO5dk9NmrXpm3HAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=LLJa0R2N; arc=none smtp.client-ip=115.124.30.98 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="LLJa0R2N" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1777988927; h=From:To:Subject:Date:Message-Id:MIME-Version:Content-Type; bh=AIhBTePeyajf+I+K0EBW6V9IUyGlhUFNxPuEI2KpBN0=; b=LLJa0R2Nq4uTZI1OpwoEOBViMjpdxtfErSZFnGpw1Al0PjMqX4N3IUszUj+FO1W4ZVx1vWMbmjOngaXQhcmSLIioLScukvhqThUSePKUoEBdiC/b5zb1lLYi8XVsTPqYNvQYrI9nZGHyZS1NMIRogVLufFHP8K4yZ1eosR7JN3Y= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R571e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam011083073210;MF=fangyu.yu@linux.alibaba.com;NM=1;PH=DS;RN=24;SR=0;TI=SMTPD_---0X2I-OJb_1777988923; Received: from localhost.localdomain(mailfrom:fangyu.yu@linux.alibaba.com fp:SMTPD_---0X2I-OJb_1777988923 cluster:ay36) by smtp.aliyun-inc.com; Tue, 05 May 2026 21:48:45 +0800 From: fangyu.yu@linux.alibaba.com To: andrew.jones@oss.qualcomm.com Cc: alex@ghiti.fr, anup@brainfault.org, aou@eecs.berkeley.edu, atish.patra@linux.dev, baolu.lu@linux.intel.com, fangyu.yu@linux.alibaba.com, guoren@kernel.org, iommu@lists.linux.dev, jgg@nvidia.com, jgg@ziepe.ca, joro@8bytes.org, kevin.tian@intel.com, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, palmer@dabbelt.com, pjw@kernel.org, robin.murphy@arm.com, skhawaja@google.com, tjeznach@rivosinc.com, vasant.hegde@amd.com, will@kernel.org Subject: Re: Re: [RFC PATCH 00/11] iommu/riscv: Add hardware dirty tracking for second-stage domains Date: Tue, 5 May 2026 21:48:42 +0800 Message-Id: <20260505134842.23549-1-fangyu.yu@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: References: 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=UTF-8 Content-Transfer-Encoding: 8bit >> From: Fangyu Yu >> >> The RISC-V IOMMU architecture defines an AMO_HWAD capability (Hardware >> Access/Dirty update) that allows the IOMMU to atomically set the A/D bits >> in second-stage PTEs on DMA access. When DC.tc.GADE is asserted, the IOMMU >> autonomously sets D on the first write to a page mapped by an iohgatp >> domain. This series wires that capability up to the iommufd dirty-tracking >> interface (IOMMU_HWPT_SET_DIRTY_TRACKING / IOMMU_HWPT_GET_DIRTY_BITMAP) and >> reports IOMMU_CAP_DIRTY_TRACKING. >> >> Design notes >> ------------ >> >> * The feature is scoped to second-stage (iohgatp) domains only; these are >> the domains created for KVM / VFIO device pass-through when userspace >> allocates an HWPT with IOMMU_HWPT_ALLOC_NEST_PARENT or >> IOMMU_HWPT_ALLOC_DIRTY_TRACKING. First-stage (iosatp) domains are not >> touched by this series. >> >> * The page-table side plugs into the existing generic_pt dirty hook >> framework (amdv1 / vtdss style). RISC-V adds the three required PTE >> ops – is_write_dirty / make_write_clean / make_write_dirty. >> >> Testing >> ------- >> >> * Test on QEMU RISC-V, a virtio-net and an e1000e device was passed through >> to an L2 guest via vfio-pci + iommufd. >> >> * generic_pt KUnit: the existing test_dirty case now runs and passes for >> the RISC-V 64-bit format. >> >> Follow-up work >> -------------- >> * Build a dedicated end-to-end test case that drives the full flow >> (HWPT_ALLOC with DIRTY_TRACKING -> attach -> IOAS_MAP -> generate real >> DMA -> SET_DIRTY_TRACKING -> GET_DIRTY_BITMAP -> verify bitmap against >> expected IOVA footprint) so that the behaviour can be regression-tested >> beyond the KUnit PTE-level coverage. >> >> * If possible, rebase and retest on top of the updated "iommu irqbypass" >> patchset. > >Thanks for this series! I was starting to go down a similar road myself >in order to limit irqbypass to IOMMU_HWPT_ALLOC_NEST_PARENT domains since >I wasn't happy with other approaches, e.g. continuing to use s-stage, but >activating g-stage too with identity mappings since the MSI table can't be >activated otherwise. Or, simply using g-stage instead of s-stage in order >to get the MSI table enabled. In the end, I think the best is to require >nested for irqbypass and this series will provide a good base for that. > >I'll rebase irqbypass on this series and test it out. > Thanks for the feedback. Jason has provided some helpful suggestions on this series, and I am in the process of updating it. I expect to send out a new version in the coming days. Fangyu >Thanks, >drew