From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: [PATCH v2 09/16] driver core: add iommu device fault reporting data Date: Fri, 6 Oct 2017 10:26:03 +0200 Message-ID: <20171006082603.GA3836@kroah.com> References: <1507244624-39189-1-git-send-email-jacob.jun.pan@linux.intel.com> <1507244624-39189-10-git-send-email-jacob.jun.pan@linux.intel.com> <20171006071145.GA24354@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20171006071145.GA24354@infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: Christoph Hellwig Cc: Jacob Pan , iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Rafael Wysocki , Jean-Philippe Brucker , Lan Tianyu List-Id: iommu@lists.linux-foundation.org On Fri, Oct 06, 2017 at 12:11:45AM -0700, Christoph Hellwig wrote: > On Thu, Oct 05, 2017 at 04:03:37PM -0700, Jacob Pan wrote: > > DMA faults can be detected by IOMMU at device level. Adding a pointer > > to struct device allows IOMMU subsystem to report relevant faults > > back to the device driver for further handling. > > For direct assigned device (or user space drivers), guest OS holds > > responsibility to handle and respond per device IOMMU fault. > > Therefore we need fault reporting mechanism to propagate faults beyond > > IOMMU subsystem. > > We use struct device all over the system, and I don't think we should > bloat it for fringe case IOMMU bits. > > Someone really needs to take a step back and figure out how to move > this into a structure that's only allocated for device that actually > can do physical DMA (and/or have an iommu attached) > > This is the 3rd iommu field, in addition to 8 dma-specific fields > that we carry around for each struct device. Ick, 8? Yeah, it's getting big... How about just a single pointer for iommu and dma-specific stuff that you all can hang crap like this off of if needed? thanks, greg k-h