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 7D5FD79F5; Fri, 4 Apr 2025 06:45:59 +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=1743749162; cv=none; b=LKRxNL+j+K+sD6zhy6ngJgoYFyGg2P/pkq+1Dbp7WrKU60S3Ty2aZS5q4TFWP3aZt30SydOvFb7+PutCTZ/uCnONsel6poDAqa4oeNma6xOXaZ0eoFad4mh5RGZ9wfcqiQV/VOn/RSM2ywlOfQ4ruUMbuhi115RKeewYIw1+tzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743749162; c=relaxed/simple; bh=uUWg9QhErzXI9QGfmIU6XMMspD+vl5V0pvC/GXoEARE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=piL1F5XqDZ+Njk0+BLt0EDoMC7MfzDXV4/HhC+NZ3StZKnIbsjNGDWv6wT7svLF3DhKBObd4iGJUy+sGMsKTMffew/TsmwAj2rVjIqAzkiWaakuh3sXTqu3VqtyuOFFLQ3ePPil5Upxgym4dXQJbzZzbIs03Vvld5kO73MMxLUg= 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=RlWJmOJX; 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="RlWJmOJX" 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=EGXw7PEXY3s5iB8Oj1X2X1hvn8HladWfj1rgTSNVE68=; b=RlWJmOJX52t+LCpesEj4XAsm+2 dt2t3mL9vib+D/KcR/fNXz6kYPcNIdSfnkkS2oDC0vmFplZOy2+zcaIsUTv/PiH/VoXcSko4Yn4R/ yEWc0CU2JP3PR045LCFvmzZy//ZjA2Uno7Jm9Q58Po62/RjCzd4tgjrG30ssTdReu2ifYpTAw3rFT 9EAB4iKoCE73sNpRXaAj/k9kIi9jGCDNTKC3lhf5wBQkrd6fTP2EfUPbPCc0IytpJLZA9L/+m0vRu 6jo4g5FPfAXfnL3OJTaewwFC0lxS9G2k/NFBzVfLDeujWF1PnV8vOzAKpNT5ryQkdOWkOea0dLYk7 dvGV1RHg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.1 #2 (Red Hat Linux)) id 1u0aoQ-0000000AurD-3mln; Fri, 04 Apr 2025 06:45:58 +0000 Date: Thu, 3 Apr 2025 23:45:58 -0700 From: Christoph Hellwig To: David Woodhouse Cc: Christoph Hellwig , "Michael S. Tsirkin" , virtio-comment@lists.linux.dev, Claire Chang , linux-devicetree , Rob Herring , =?iso-8859-1?Q?J=F6rg?= Roedel , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, graf@amazon.de Subject: Re: [RFC PATCH 1/3] content: Add VIRTIO_F_SWIOTLB to negotiate use of SWIOTLB bounce buffers Message-ID: References: <965ccf2f972c5d5f1f4edacb227f03171f20e887.camel@infradead.org> <20250402124131-mutt-send-email-mst@kernel.org> <06465bcf4422d088df2a0ce9cdb09767dac83118.camel@infradead.org> <488D32C6-77FA-4CC8-988F-CD4D14548D4B@infradead.org> 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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Thu, Apr 03, 2025 at 11:44:40PM -0700, Christoph Hellwig wrote: > That's what NVMe currently does in it's second attempt to get things > wrong. It mostly works for the current use cases, but there might > actually not be a single canonical address where it is mapped. This > was mostly theoretical, but with SVM and especially SIOV it is becoming > a real thing now. > > In the worst case you might have to limit yourself to one address space > per request. Or have a bitmap which buffer in the request uses which > address space. Also with unordered I/O in the newer PCIe specs we might need another such address space bit to force use of that for certain ranges, although system use cases for UIO are still not finalized.