From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 A54451CD2D; Thu, 2 May 2024 05:07:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714626460; cv=none; b=t4XmXykYh1fdk64f9sqksl4SEqJwSOJauhMwIcfFMOtqZO3PIpWjMVDRM2ZM2pNIZ96umh+zPpSNHz071XM3sMtYuyMnz1YTkWGHpBJIxwQ4rRvQ8zsll7Kiin/ca962FWaHcXeJA2amkysOU+eI+qcABqwxuFS8jqINkyGPonk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714626460; c=relaxed/simple; bh=5amkvJXIOOx9Ih8Muv99+02q4fS2kw8BvMZGGjfEC+g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oDtOc49hCopIN17HIhpENpSjJckt06YrTg3ywnzdlXaQx/aVZkJL1pVwrK4Y/axIwsGO5mFrwNMlS7FxlpnU13w5dC/cDD3ATTnFsVsD0hJuDD0pgwXV/dYDLQgqH3/vCb/UspuJhWASC+meET5p92ydyb6sth0h0bH+iv9WsfM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=PAwC3HGz; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PAwC3HGz" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=5amkvJXIOOx9Ih8Muv99+02q4fS2kw8BvMZGGjfEC+g=; b=PAwC3HGzIePWCQ0yHyz8Bb+PhF FqB2JAjzpMjOl51lbRLUYcHVwT+HzhbkR5zgW7jgdslvznS6S/gC1rnNBbMP6OTIjDXrFJmYYImtA FU9OhWDPruICJEBrU008uW+W5j0mhCVn6O2XxRULjN1pn7+wPyQt2eenzsiSTZZ8CW4jDJhMORiwQ Izq/NNYzoXIjkwU6Ut0yDfTr/n+kpFw07YmATMN4qcD+18wOkiQ8dyeams8en1F9ElCFTR8k4Tvef T2umHYKSjWnHTSnHFTgQHJLNWmCWsjrpY49PeFyd36XgkJa4pfIQY+xMhRtQvzVU9zGhvpB14zvpV BH6dDqXg==; Received: from hch by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s2OfP-0000000BUUU-36bi; Thu, 02 May 2024 05:07:35 +0000 Date: Wed, 1 May 2024 22:07:35 -0700 From: Christoph Hellwig To: "T.J. Mercier" Cc: Robin Murphy , Joerg Roedel , Will Deacon , Andrew Morton , Catalin Marinas , isaacmanjarres@google.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iommu/dma: Respect SWIOTLB force_bounce Message-ID: References: <20240501201319.586289-1-tjmercier@google.com> 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=us-ascii Content-Disposition: inline In-Reply-To: <20240501201319.586289-1-tjmercier@google.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, May 01, 2024 at 08:13:18PM +0000, T.J. Mercier wrote: > iommu_dma_map_page and iommu_dma_map_sg conditionally use SWIOTLB, but > checking if force_bounce is set for the device is not part of that > condition. Check if devices have requested to force SWIOTLB use as part > of deciding to take the existing SWIOTLB paths. This fails to explain why you'd want this somewhat surprising behavior, and why you consider it a bug fix.