From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754534AbaCYS4v (ORCPT ); Tue, 25 Mar 2014 14:56:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63719 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753009AbaCYS4u (ORCPT ); Tue, 25 Mar 2014 14:56:50 -0400 Message-ID: <1395773793.632.152.camel@ul30vt.home> Subject: Re: [RFC PATCH v4 06/10] VFIO_PLATFORM: Read and write support for the device fd From: Alex Williamson To: Eric Auger Cc: a.motakis@virtualopensystems.com, kvmarm@lists.cs.columbia.edu, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, tech@virtualopensystems.com, a.rigo@virtualopensystems.com, B08248@freescale.com, kim.phillips@linaro.org, jan.kiszka@siemens.com, kvm@vger.kernel.org, R65777@freescale.com, B07421@freescale.com, christoffer.dall@linaro.org, agraf@suse.de, B16395@freescale.com, will.deacon@arm.com Date: Tue, 25 Mar 2014 12:56:33 -0600 In-Reply-To: <5331B22C.6090100@linaro.org> References: <20140325110619.52107df5d6d0cf0476b33cd4@linaro.org> <5331B22C.6090100@linaro.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2014-03-25 at 17:43 +0100, Eric Auger wrote: > > Date: Sat, 8 Feb 2014 18:29:36 +0100 > > VFIO returns a file descriptor which we can use to manipulate the memory > > regions of the device. Since some memory regions we cannot mmap due to > > security concerns, we also allow to read and write to this file descriptor > > directly. > > > > Signed-off-by: Antonios Motakis > > Tested-by: Alvise Rigo > > --- > > drivers/vfio/platform/vfio_platform.c | 128 +++++++++++++++++++++++++++++++++- > > 1 file changed, 125 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c > > index f7db5c0..ee96078 100644 > > --- a/drivers/vfio/platform/vfio_platform.c > > +++ b/drivers/vfio/platform/vfio_platform.c > > @@ -55,7 +55,8 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev) > > > > region.addr = res->start; > > region.size = resource_size(res); > > - region.flags = 0; > > + region.flags = VFIO_REGION_INFO_FLAG_READ > > + | VFIO_REGION_INFO_FLAG_WRITE; > > > > vdev->region[i] = region; > > } > > @@ -150,13 +151,134 @@ static long vfio_platform_ioctl(void *device_data, > > static ssize_t vfio_platform_read(void *device_data, char __user *buf, > > size_t count, loff_t *ppos) > > { > > - return 0; > > + struct vfio_platform_device *vdev = device_data; > > + unsigned int *io; > > + int i; > > + > > + for (i = 0; i < vdev->num_regions; i++) { > > + struct vfio_platform_region region = vdev->region[i]; > > + unsigned int done = 0; > > + loff_t off; > > + > > + if ((*ppos < region.addr) > > + || (*ppos + count - 1) >= (region.addr + region.size)) > > + continue; > > + > > + io = ioremap_nocache(region.addr, region.size); > > + > > + off = *ppos - region.addr; > > + > > + while (count) { > > + size_t filled; > > + > > + if (count >= 4 && !(off % 4)) { > > + u32 val; > > + > > + val = ioread32(io + off); > > Hi Antonios, > > I suspect there is an issue with the read address. Indeed io being an > unsigned int* the read address is io + off x sizeof (unsigned int) ie. > io+ offx4 whereas we expect to read io + off. declaring io as a void* > corrects the issue (or void __iomem *io). Same issue on write. Yep, the same code for vfio/pci uses void __iomem *io. Thanks, Alex