From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A92031079B for ; Wed, 31 Dec 2025 13:12:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767186755; cv=none; b=k7ClFkTWvQdF41TyrFEEpvU04qYk3g0yOXi0+pw3kDofdhJrv8uaFA5gwszZQ/q8u8EtHKLCtRLl9jxrVasdOo2ArmaOpTTbDi5Rs6iLa+J5e+XEY78NC4bwMGDWq5v2e9/t9+a5PSzuFaPGSw4lUZx+WGLkWKlUHy7rZSXJtAQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767186755; c=relaxed/simple; bh=+Rj9uS/xKO+b+rZgqDTkOPQ7AM9H+O0zY3sW6JnGIaQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=PpJ0f5FeTWJXATvNIDLQC/7XAQQItgJmzrvNunUFR8QDZY/1ca+WQmg1pQvNVDe9WA5ZeE42Ub/J3lC7we7+h4p2NHO32EjuJo6dNaFIAvMEk05so67zw1oB7man2omC6xU9qvhT4IqwmNepdUadZ/Qmo3BtIimTiNbvygJLuCY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=SiNOf5hC; arc=none smtp.client-ip=209.85.128.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="SiNOf5hC" Received: by mail-wm1-f47.google.com with SMTP id 5b1f17b1804b1-47d538fafdfso3024555e9.1 for ; Wed, 31 Dec 2025 05:12:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1767186751; x=1767791551; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=Fke3G5rSH2WPZ2DuQdyfqEfEpoI6l76uJNtI0EpEhAo=; b=SiNOf5hCQAQ9lih0xDGV7gjR7CfpmOO8AB3s9IeITfpaC328pdo654nC3FNIfPPnYB fkd5qD9q+HvWSq536C6BhTSPieAbHLipRfLKE21iDDYtDmghplktpIhdpDtdORPciAcZ LQpQ8PKMM8Q6/YUI7t1QvsKoPzRYURS1J27f9/F31nTEFyFQlVX8XQzAr1xtRLQ39GkB REQ15nkajDKe1xg9zkDXa/UH9tt1LtbNShtNDDvRc1UpIXkWn8dwnUZCTvot/hexmBta XggYEqQC1GM23pJ7GQgNCAuwh+5a70MQJiobGXUg7XwbkgAb1lDG3040If49qmyX801q 2gDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767186751; x=1767791551; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=Fke3G5rSH2WPZ2DuQdyfqEfEpoI6l76uJNtI0EpEhAo=; b=daLnRl+Dw4KtEqxSZH4v+9SLSkXdeUbhNQd0bhvsICq1p1+3WoShhUPi+9GshrDrAS O1NzQZoVHRyOKKScVD78DELqYZI5TMY7SDCm0kS4iiIQcKHEOIiFIa88cpZOYpBShR3N tpoQt2/L8QJ7c0g/40PHHTkzR3PBNzzqxOXQYvH0QjsWK8O1GkAI2a0X6ELdzAy1NNIu vFkeju57pGLx77cUCM7UofD0bmc/SUMtXE/9Rq8p7pR8PEHp7GSdOb4WHoIO3QJnBRsc 34sdqErNmhQfdeiFU2ZNy5OXTKDuusJ+a6GxofR+q4aHqPry0qJpcMF3iUtcOAM9U6PZ U4bw== X-Forwarded-Encrypted: i=1; AJvYcCUkcJHCIbeYC5XMBC9n/kaFfIX+muVP7DCP1sdcyMGx6fswYjajrOgzqYJVXPTMLuVI9xNRBzGfeTl8@vger.kernel.org X-Gm-Message-State: AOJu0YzpcnIEiu57cpaiL1R/XcoVzAi1CiFiQgiHkECRZhpWDald+8Xf J/QqjOJ/xhBsMYe3KNGV/QfN/i6wiMlNTq3pUU3hfxaQyukaxCpd4zOVSk0AWcoPnAo= X-Gm-Gg: AY/fxX7PVR7JysupDbcKlO6dxg9g31eFwVFCHzpsnJZPxFHtrORiohLUUpFX4THmVPO lu/3xm8N7vQ77C6YiQHnEUiElPQpzNNcmG/5e0w3m2Kgt0HoVrmBYoYm7OD92H8AwDNMo4ZIMMZ 4gAq5zth76lvVnDJTYXDBRryWnk7EHIhXIK5qj7tytldjrjy47gImGqMQjB4uZmX1HrzkXy2tdZ pmV6VxaWA8NcAcEsURBi3DDYUzLie0ocLLSCJoxIyJPrGYPCkK8Q0XwiMfO0spLm3145+yI9ieK L3pIsTzbFuSK93WL8uzvJVN+nBr+YouAWVf/E3ZdUxPlQHKqlsGecbJoHgxJhv6WCKAwgkvRk16 SbA0aaUYpmYDTUIN3mWpv5nY+y1HFEbZmbJv5rNcR+p+wjWE+K7tjhLiFoim3O7uQQJ+gV183z6 41if7xvn+VFX0X38qCr/6deg6690fJe5Xdpwz3mUQMLvTgJ64oc94vm1fWBmv5aRSfxvZ5LYyeT 2AG X-Google-Smtp-Source: AGHT+IF4mp6GOV5G6x95wPZOhGbqasawR+ZO3M57T/TzQMfUeMdF8kArZ+ePMOUwA5I3JuKmTuDssg== X-Received: by 2002:a05:600c:3e0b:b0:477:9c73:268a with SMTP id 5b1f17b1804b1-47d195b3d55mr287631655e9.6.1767186751342; Wed, 31 Dec 2025 05:12:31 -0800 (PST) Received: from mordecai (dynamic-2a00-1028-83b8-1e7a-3010-3bd6-8521-caf1.ipv6.o2.cz. [2a00:1028:83b8:1e7a:3010:3bd6:8521:caf1]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47be3a20af0sm269524875e9.4.2025.12.31.05.12.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 31 Dec 2025 05:12:30 -0800 (PST) Date: Wed, 31 Dec 2025 14:12:24 +0100 From: Petr Tesarik To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Cong Wang , Jonathan Corbet , Olivia Mackall , Herbert Xu , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Eugenio =?UTF-8?B?UMOpcmV6?= , "James E.J. Bottomley" , "Martin K. Petersen" , Gerd Hoffmann , Xuan Zhuo , Marek Szyprowski , Robin Murphy , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Leon Romanovsky , Jason Gunthorpe , linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, virtualization@lists.linux.dev, linux-scsi@vger.kernel.org, iommu@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH RFC 00/13] fix DMA aligment issues around virtio Message-ID: <20251231141224.56d4ce56@mordecai> In-Reply-To: References: X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-suse-linux-gnu) Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 30 Dec 2025 05:15:42 -0500 "Michael S. Tsirkin" wrote: > Cong Wang reported dma debug warnings with virtio-vsock > and proposed a patch, see: > > https://lore.kernel.org/all/20251228015451.1253271-1-xiyou.wangcong@gmail.com/ > > however, the issue is more widespread. > This is an attempt to fix it systematically. > Note: i2c and gio might also be affected, I am still looking > into it. Help from maintainers welcome. > > Early RFC, compile tested only. Sending for early feedback/flames. > Cursor/claude used liberally mostly for refactoring, and english. > > DMA maintainers, could you please confirm the DMA core changes > are ok with you? Before anyone else runs into the same issue as I did: This patch series does not apply cleanly unless you first apply commit b148e85c918a ("virtio_ring: switch to use vring_virtqueue for virtqueue_add variants") from the mst/vhost/vhost branch. But if you go to the trouble of adding the mst/vhost remote, then the above-mentioned branch also contains this patch series, and it's probably the best place to find the patched code... Now, let me set out for review. Petr T > Thanks! > > > Michael S. Tsirkin (13): > dma-mapping: add __dma_from_device_align_begin/end > docs: dma-api: document __dma_align_begin/end > dma-mapping: add DMA_ATTR_CPU_CACHE_CLEAN > docs: dma-api: document DMA_ATTR_CPU_CACHE_CLEAN > dma-debug: track cache clean flag in entries > virtio: add virtqueue_add_inbuf_cache_clean API > vsock/virtio: fix DMA alignment for event_list > vsock/virtio: use virtqueue_add_inbuf_cache_clean for events > virtio_input: fix DMA alignment for evts > virtio_scsi: fix DMA cacheline issues for events > virtio-rng: fix DMA alignment for data buffer > virtio_input: use virtqueue_add_inbuf_cache_clean for events > vsock/virtio: reorder fields to reduce struct padding > > Documentation/core-api/dma-api-howto.rst | 42 +++++++++++++ > Documentation/core-api/dma-attributes.rst | 9 +++ > drivers/char/hw_random/virtio-rng.c | 2 + > drivers/scsi/virtio_scsi.c | 18 ++++-- > drivers/virtio/virtio_input.c | 5 +- > drivers/virtio/virtio_ring.c | 72 +++++++++++++++++------ > include/linux/dma-mapping.h | 17 ++++++ > include/linux/virtio.h | 5 ++ > kernel/dma/debug.c | 26 ++++++-- > net/vmw_vsock/virtio_transport.c | 8 ++- > 10 files changed, 172 insertions(+), 32 deletions(-) >