From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [RFC PATCH v4 06/10] VFIO_PLATFORM: Read and write support for the device fd Date: Tue, 25 Mar 2014 12:56:33 -0600 Message-ID: <1395773793.632.152.camel@ul30vt.home> References: <20140325110619.52107df5d6d0cf0476b33cd4@linaro.org> <5331B22C.6090100@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5331B22C.6090100-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Eric Auger Cc: B07421-KZfg59tc24xl57MIdRCFDg@public.gmane.org, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, agraf-l3A5Bk7waGM@public.gmane.org, R65777-KZfg59tc24xl57MIdRCFDg@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, a.rigo-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org, B08248-KZfg59tc24xl57MIdRCFDg@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org, a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org, tech-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org, kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org, christoffer.dall-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org List-Id: iommu@lists.linux-foundation.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