From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [RFC PATCH v5 08/11] VFIO_PLATFORM: Support MMAP of MMIO regions Date: Mon, 28 Apr 2014 11:27:22 -0600 Message-ID: <1398706042.24318.287.camel@ul30vt.home> References: <1398700371-20096-1-git-send-email-a.motakis@virtualopensystems.com> <1398700371-20096-9-git-send-email-a.motakis@virtualopensystems.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1398700371-20096-9-git-send-email-a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@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: Antonios Motakis Cc: kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, open list , will.deacon-5wv7dgnIgG8@public.gmane.org, a.rigo-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org, stuart.yoder-KZfg59tc24xl57MIdRCFDg@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@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 Mon, 2014-04-28 at 17:52 +0200, Antonios Motakis wrote: > Allow to memory map the MMIO regions of the device so userspace can > directly access them. > > Signed-off-by: Antonios Motakis > --- > drivers/vfio/platform/vfio_platform.c | 40 ++++++++++++++++++++++++++++++++++- > 1 file changed, 39 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c > index 7c01ced..37beff3 100644 > --- a/drivers/vfio/platform/vfio_platform.c > +++ b/drivers/vfio/platform/vfio_platform.c > @@ -58,6 +58,11 @@ static int vfio_platform_regions_init(struct vfio_platform_device *vdev) > region.flags = VFIO_REGION_INFO_FLAG_READ > | VFIO_REGION_INFO_FLAG_WRITE; > > + /* Only regions addressed with PAGE granularity can be MMAPed > + * securely. */ > + if (!(region.addr & ~PAGE_MASK) && !(region.size & ~PAGE_MASK)) > + region.flags |= VFIO_REGION_INFO_FLAG_MMAP; > + Ok, so the security is only that we need page alignment. Maybe that could be made more clear in the previous patch. PCI has regions like the MSI-X table that we need to protect from userspace access beyond page alignment requirements. Thanks, Alex > vdev->region[i] = region; > } > > @@ -268,7 +273,40 @@ err: > > static int vfio_platform_mmap(void *device_data, struct vm_area_struct *vma) > { > - return -EINVAL; > + struct vfio_platform_device *vdev = device_data; > + unsigned int index; > + u64 req_len, pgoff, req_start; > + struct vfio_platform_region region; > + > + index = vma->vm_pgoff >> (VFIO_PLATFORM_OFFSET_SHIFT - PAGE_SHIFT); > + > + if (vma->vm_end < vma->vm_start) > + return -EINVAL; > + if ((vma->vm_flags & VM_SHARED) == 0) > + return -EINVAL; > + if (index >= vdev->num_regions) > + return -EINVAL; > + if (vma->vm_start & ~PAGE_MASK) > + return -EINVAL; > + if (vma->vm_end & ~PAGE_MASK) > + return -EINVAL; > + > + region = vdev->region[index]; > + > + req_len = vma->vm_end - vma->vm_start; > + pgoff = vma->vm_pgoff & > + ((1U << (VFIO_PLATFORM_OFFSET_SHIFT - PAGE_SHIFT)) - 1); > + req_start = pgoff << PAGE_SHIFT; > + > + if (region.size < PAGE_SIZE || req_start + req_len > region.size) > + return -EINVAL; > + > + vma->vm_private_data = vdev; > + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > + vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff; > + > + return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, > + req_len, vma->vm_page_prot); > } > > static const struct vfio_device_ops vfio_platform_ops = {