From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout2.w1.samsung.com (mailout2.w1.samsung.com [210.118.77.12]) (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 577F11EE02F; Mon, 1 Sep 2025 21:48:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.118.77.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756763289; cv=none; b=tNGlMFIDFbThL65Mn5znPj3nLzP6qqLUr74g4ic4IQ1M8rdCIeOD2GwfiynXs8zAHZ5uDXpuOLXZctw5nCwQLHLh91VzliGByYrS+JO7rcsXgpfQBM1mkQrQ2mU9pVmN4e2QnlIJAo+hkEVAVtenShCxWeMF9DwVhCb7fbrDTSg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756763289; c=relaxed/simple; bh=zOVqnT4CiNvqIL9ntGVIBSSZLn7RBEB0Hk45iI1LVYU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:From:In-Reply-To: Content-Type:References; b=QNFi1vcHqsO9Iop5C6TSekWmesIK9JxZnPXGwZgCtYWrY5dPP+RF+WCGgQeAH8CYsyC/86/eoGNIWYqOwnWnDxO3OxCmspnz93AsQNz6GeI+90WsVhaVnAEPOJ53v1Fm1/LQCpxSdEK0tsU/kRN7noVbeNqYrWIYxd5y8z9ghek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=FxjRf7+C; arc=none smtp.client-ip=210.118.77.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="FxjRf7+C" Received: from eucas1p1.samsung.com (unknown [182.198.249.206]) by mailout2.w1.samsung.com (KnoxPortal) with ESMTP id 20250901214803euoutp02d79d0cf4cda6546a5817575ed420314a~hRuYkNP0O2070420704euoutp02b; Mon, 1 Sep 2025 21:48:03 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout2.w1.samsung.com 20250901214803euoutp02d79d0cf4cda6546a5817575ed420314a~hRuYkNP0O2070420704euoutp02b DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1756763283; bh=nDcHitW6y2xbmXlK2jIcbndjdtco2y22djXFkarI+Kk=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=FxjRf7+Ccpl7snsYCn9LacCiGJXvASl2Bcyshcc3MWcU7wbky050oQOcx4xKJlMqc EH1xZePjtKif6niNm/ZZNmDVZoJ/hrllrH2T7muDX2gjk12tpAmaQkZRCflGuSDB6/ tvmSX006Ss83xwBwmshU6YU5Q3rwG2epCzq8Yjqg= Received: from eusmtip2.samsung.com (unknown [203.254.199.222]) by eucas1p2.samsung.com (KnoxPortal) with ESMTPA id 20250901214802eucas1p2e3b4b360d054bc640a8654e364047c28~hRuXfQpr52428424284eucas1p2C; Mon, 1 Sep 2025 21:48:02 +0000 (GMT) Received: from [106.210.134.192] (unknown [106.210.134.192]) by eusmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250901214759eusmtip26af756ba90f133971e3a66f9c5275b48~hRuUiYUac1463914639eusmtip2j; Mon, 1 Sep 2025 21:47:59 +0000 (GMT) Message-ID: <26bd901a-0812-492d-9736-4a7bb2e6d6b4@samsung.com> Date: Mon, 1 Sep 2025 23:47:59 +0200 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Betterbird (Windows) Subject: Re: [PATCH v4 00/16] dma-mapping: migrate to physical address-based API To: Leon Romanovsky Cc: Jason Gunthorpe , Abdiel Janulgue , Alexander Potapenko , Alex Gaynor , Andrew Morton , Christoph Hellwig , Danilo Krummrich , iommu@lists.linux.dev, Jason Wang , Jens Axboe , Joerg Roedel , Jonathan Corbet , Juergen Gross , kasan-dev@googlegroups.com, Keith Busch , linux-block@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-nvme@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, Madhavan Srinivasan , Masami Hiramatsu , Michael Ellerman , "Michael S. Tsirkin" , Miguel Ojeda , Robin Murphy , rust-for-linux@vger.kernel.org, Sagi Grimberg , Stefano Stabellini , Steven Rostedt , virtualization@lists.linux.dev, Will Deacon , xen-devel@lists.xenproject.org Content-Language: en-US From: Marek Szyprowski In-Reply-To: <20250828115729.GA10073@unreal> Content-Transfer-Encoding: 8bit X-CMS-MailID: 20250901214802eucas1p2e3b4b360d054bc640a8654e364047c28 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20250828115738eucas1p24f3c17326b318c95a5569a2c9651ff92 X-EPHeader: CA X-CMS-RootMailID: 20250828115738eucas1p24f3c17326b318c95a5569a2c9651ff92 References: <20250828115729.GA10073@unreal> On 28.08.2025 13:57, Leon Romanovsky wrote: > On Tue, Aug 19, 2025 at 08:36:44PM +0300, Leon Romanovsky wrote: >> Changelog: >> v4: >> * Fixed kbuild error with mismatch in kmsan function declaration due to >> rebase error. >> v3: https://lore.kernel.org/all/cover.1755193625.git.leon@kernel.org >> * Fixed typo in "cacheable" word >> * Simplified kmsan patch a lot to be simple argument refactoring >> v2: https://lore.kernel.org/all/cover.1755153054.git.leon@kernel.org >> * Used commit messages and cover letter from Jason >> * Moved setting IOMMU_MMIO flag to dma_info_to_prot function >> * Micro-optimized the code >> * Rebased code on v6.17-rc1 >> v1: https://lore.kernel.org/all/cover.1754292567.git.leon@kernel.org >> * Added new DMA_ATTR_MMIO attribute to indicate >> PCI_P2PDMA_MAP_THRU_HOST_BRIDGE path. >> * Rewrote dma_map_* functions to use thus new attribute >> v0: https://lore.kernel.org/all/cover.1750854543.git.leon@kernel.org/ >> ------------------------------------------------------------------------ >> >> This series refactors the DMA mapping to use physical addresses >> as the primary interface instead of page+offset parameters. This >> change aligns the DMA API with the underlying hardware reality where >> DMA operations work with physical addresses, not page structures. >> >> The series maintains export symbol backward compatibility by keeping >> the old page-based API as wrapper functions around the new physical >> address-based implementations. >> >> This series refactors the DMA mapping API to provide a phys_addr_t >> based, and struct-page free, external API that can handle all the >> mapping cases we want in modern systems: >> >> - struct page based cachable DRAM >> - struct page MEMORY_DEVICE_PCI_P2PDMA PCI peer to peer non-cachable >> MMIO >> - struct page-less PCI peer to peer non-cachable MMIO >> - struct page-less "resource" MMIO >> >> Overall this gets much closer to Matthew's long term wish for >> struct-pageless IO to cachable DRAM. The remaining primary work would >> be in the mm side to allow kmap_local_pfn()/phys_to_virt() to work on >> phys_addr_t without a struct page. >> >> The general design is to remove struct page usage entirely from the >> DMA API inner layers. For flows that need to have a KVA for the >> physical address they can use kmap_local_pfn() or phys_to_virt(). This >> isolates the struct page requirements to MM code only. Long term all >> removals of struct page usage are supporting Matthew's memdesc >> project which seeks to substantially transform how struct page works. >> >> Instead make the DMA API internals work on phys_addr_t. Internally >> there are still dedicated 'page' and 'resource' flows, except they are >> now distinguished by a new DMA_ATTR_MMIO instead of by callchain. Both >> flows use the same phys_addr_t. >> >> When DMA_ATTR_MMIO is specified things work similar to the existing >> 'resource' flow. kmap_local_pfn(), phys_to_virt(), phys_to_page(), >> pfn_valid(), etc are never called on the phys_addr_t. This requires >> rejecting any configuration that would need swiotlb. CPU cache >> flushing is not required, and avoided, as ATTR_MMIO also indicates the >> address have no cachable mappings. This effectively removes any >> DMA API side requirement to have struct page when DMA_ATTR_MMIO is >> used. >> >> In the !DMA_ATTR_MMIO mode things work similarly to the 'page' flow, >> except on the common path of no cache flush, no swiotlb it never >> touches a struct page. When cache flushing or swiotlb copying >> kmap_local_pfn()/phys_to_virt() are used to get a KVA for CPU >> usage. This was already the case on the unmap side, now the map side >> is symmetric. >> >> Callers are adjusted to set DMA_ATTR_MMIO. Existing 'resource' users >> must set it. The existing struct page based MEMORY_DEVICE_PCI_P2PDMA >> path must also set it. This corrects some existing bugs where iommu >> mappings for P2P MMIO were improperly marked IOMMU_CACHE. >> >> Since ATTR_MMIO is made to work with all the existing DMA map entry >> points, particularly dma_iova_link(), this finally allows a way to use >> the new DMA API to map PCI P2P MMIO without creating struct page. The >> VFIO DMABUF series demonstrates how this works. This is intended to >> replace the incorrect driver use of dma_map_resource() on PCI BAR >> addresses. >> >> This series does the core code and modern flows. A followup series >> will give the same treatment to the legacy dma_ops implementation. >> >> Thanks >> >> Leon Romanovsky (16): >> dma-mapping: introduce new DMA attribute to indicate MMIO memory >> iommu/dma: implement DMA_ATTR_MMIO for dma_iova_link(). >> dma-debug: refactor to use physical addresses for page mapping >> dma-mapping: rename trace_dma_*map_page to trace_dma_*map_phys >> iommu/dma: rename iommu_dma_*map_page to iommu_dma_*map_phys >> iommu/dma: extend iommu_dma_*map_phys API to handle MMIO memory >> dma-mapping: convert dma_direct_*map_page to be phys_addr_t based >> kmsan: convert kmsan_handle_dma to use physical addresses >> dma-mapping: handle MMIO flow in dma_map|unmap_page >> xen: swiotlb: Open code map_resource callback >> dma-mapping: export new dma_*map_phys() interface >> mm/hmm: migrate to physical address-based DMA mapping API >> mm/hmm: properly take MMIO path >> block-dma: migrate to dma_map_phys instead of map_page >> block-dma: properly take MMIO path >> nvme-pci: unmap MMIO pages with appropriate interface >> >> Documentation/core-api/dma-api.rst | 4 +- >> Documentation/core-api/dma-attributes.rst | 18 ++++ >> arch/powerpc/kernel/dma-iommu.c | 4 +- >> block/blk-mq-dma.c | 15 ++- >> drivers/iommu/dma-iommu.c | 61 +++++------ >> drivers/nvme/host/pci.c | 18 +++- >> drivers/virtio/virtio_ring.c | 4 +- >> drivers/xen/swiotlb-xen.c | 21 +++- >> include/linux/blk-mq-dma.h | 6 +- >> include/linux/blk_types.h | 2 + >> include/linux/dma-direct.h | 2 - >> include/linux/dma-map-ops.h | 8 +- >> include/linux/dma-mapping.h | 33 ++++++ >> include/linux/iommu-dma.h | 11 +- >> include/linux/kmsan.h | 9 +- >> include/trace/events/dma.h | 9 +- >> kernel/dma/debug.c | 71 ++++--------- >> kernel/dma/debug.h | 37 ++----- >> kernel/dma/direct.c | 22 +--- >> kernel/dma/direct.h | 52 ++++++---- >> kernel/dma/mapping.c | 117 +++++++++++++--------- >> kernel/dma/ops_helpers.c | 6 +- >> mm/hmm.c | 19 ++-- >> mm/kmsan/hooks.c | 5 +- >> rust/kernel/dma.rs | 3 + >> tools/virtio/linux/kmsan.h | 2 +- >> 26 files changed, 305 insertions(+), 254 deletions(-) > Marek, > > So what are the next steps here? This series is pre-requirement for the > VFIO MMIO patches. I waited a bit with a hope to get a comment from Robin. It looks that there is no other alternative for the phys addr in the struct page removal process. I would like to give those patches a try in linux-next, but in meantime I tested it on my test farm and found a regression in dma_map_resource() handling. Namely the dma_map_resource() is no longer possible with size not aligned to kmalloc()'ed buffer, as dma_direct_map_phys() calls dma_kmalloc_needs_bounce(), which in turn calls dma_kmalloc_size_aligned(). It looks that the check for !(attrs & DMA_ATTR_MMIO) should be moved one level up in dma_direct_map_phys(). Here is the log: ------------[ cut here ]------------ dma-pl330 fe550000.dma-controller: DMA addr 0x00000000fe410024+4 overflow (mask ffffffff, bus limit 0). WARNING: kernel/dma/direct.h:116 at dma_map_phys+0x3a4/0x3ec, CPU#1: speaker-test/405 Modules linked in: ... CPU: 1 UID: 0 PID: 405 Comm: speaker-test Not tainted 6.17.0-rc4-next-20250901+ #10958 PREEMPT Hardware name: Hardkernel ODROID-M1 (DT) pstate: 604000c9 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : dma_map_phys+0x3a4/0x3ec lr : dma_map_phys+0x3a4/0x3ec ... Call trace:  dma_map_phys+0x3a4/0x3ec (P)  dma_map_resource+0x14/0x20  pl330_prep_slave_fifo+0x78/0xd0  pl330_prep_dma_cyclic+0x70/0x2b0  snd_dmaengine_pcm_trigger+0xec/0x8bc [snd_pcm_dmaengine]  dmaengine_pcm_trigger+0x18/0x24 [snd_soc_core]  snd_soc_pcm_component_trigger+0x164/0x208 [snd_soc_core]  soc_pcm_trigger+0xe4/0x1ec [snd_soc_core]  snd_pcm_do_start+0x44/0x70 [snd_pcm]  snd_pcm_action_single+0x48/0xa4 [snd_pcm]  snd_pcm_action+0x7c/0x98 [snd_pcm]  snd_pcm_action_lock_irq+0x48/0xb4 [snd_pcm]  snd_pcm_common_ioctl+0xf00/0x1f1c [snd_pcm]  snd_pcm_ioctl+0x30/0x48 [snd_pcm]  __arm64_sys_ioctl+0xac/0x104  invoke_syscall+0x48/0x110  el0_svc_common.constprop.0+0x40/0xe8  do_el0_svc+0x20/0x2c  el0_svc+0x4c/0x160  el0t_64_sync_handler+0xa0/0xe4  el0t_64_sync+0x198/0x19c irq event stamp: 6596 hardirqs last  enabled at (6595): [] _raw_spin_unlock_irqrestore+0x74/0x78 hardirqs last disabled at (6596): [] _raw_spin_lock_irq+0x78/0x7c softirqs last  enabled at (6076): [] handle_softirqs+0x4c4/0x4dc softirqs last disabled at (6071): [] __do_softirq+0x14/0x20 ---[ end trace 0000000000000000 ]--- rockchip-i2s-tdm fe410000.i2s: ASoC error (-12): at soc_component_trigger() on fe410000.i2s Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland