Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757581AbaD2N3O (ORCPT ); Tue, 29 Apr 2014 09:29:14 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:38220 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756856AbaD2N3L (ORCPT ); Tue, 29 Apr 2014 09:29:11 -0400 MIME-Version: 1.0 X-Originating-IP: [82.67.68.96] In-Reply-To: <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> <1398706042.24318.287.camel@ul30vt.home> From: Antonios Motakis Date: Tue, 29 Apr 2014 15:28:43 +0200 Message-ID: Subject: Re: [RFC PATCH v5 08/11] VFIO_PLATFORM: Support MMAP of MMIO regions To: Alex Williamson Cc: kvm-arm , Linux IOMMU , VirtualOpenSystems Technical Team , alvise rigo , KVM devel mailing list , Christoffer Dall , Will Deacon , Kim Phillips , Stuart Yoder , open list Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 28, 2014 at 7:27 PM, Alex Williamson wrote: > 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, Ack, I will make the previous description more clear. > > 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 = { > > > -- Antonios Motakis Virtual Open Systems -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/