Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755493AbcCPQao (ORCPT ); Wed, 16 Mar 2016 12:30:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37987 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755281AbcCPQam (ORCPT ); Wed, 16 Mar 2016 12:30:42 -0400 Date: Wed, 16 Mar 2016 10:30:34 -0600 From: Alex Williamson To: Yongji Xie Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, bhelgaas@google.com, corbet@lwn.net, aik@ozlabs.ru, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, warrier@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com, nikunj@linux.vnet.ibm.com Subject: Re: [RFC PATCH v4 5/7] vfio-pci: Allow to mmap sub-page MMIO BARs if the mmio page is exclusive Message-ID: <20160316103034.48666ae0@t450s.home> In-Reply-To: <1457336918-3893-6-git-send-email-xyjxie@linux.vnet.ibm.com> References: <1457336918-3893-1-git-send-email-xyjxie@linux.vnet.ibm.com> <1457336918-3893-6-git-send-email-xyjxie@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1773 Lines: 47 On Mon, 7 Mar 2016 15:48:36 +0800 Yongji Xie wrote: > Current vfio-pci implementation disallows to mmap > sub-page(size < PAGE_SIZE) MMIO BARs because these BARs' mmio > page may be shared with other BARs. > > But we should allow to mmap these sub-page MMIO BARs if PCI > resource allocator can make sure these BARs' mmio page will > not be shared with other BARs. > > Signed-off-by: Yongji Xie > --- > drivers/vfio/pci/vfio_pci.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > index 1ce1d36..49d7a69 100644 > --- a/drivers/vfio/pci/vfio_pci.c > +++ b/drivers/vfio/pci/vfio_pci.c > @@ -589,7 +589,8 @@ static long vfio_pci_ioctl(void *device_data, > VFIO_REGION_INFO_FLAG_WRITE; > if (IS_ENABLED(CONFIG_VFIO_PCI_MMAP) && > pci_resource_flags(pdev, info.index) & > - IORESOURCE_MEM && info.size >= PAGE_SIZE) { > + IORESOURCE_MEM && !pci_resources_share_page(pdev, > + info.index)) { this would be a preferable line wrap: IORESOURCE_MEM && !pci_resources_share_page(pdev, info.index)) { > info.flags |= VFIO_REGION_INFO_FLAG_MMAP; > if (info.index == vdev->msix_bar) { > ret = msix_sparse_mmap_cap(vdev, &caps); > @@ -1016,6 +1017,10 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma) > return -EINVAL; > > phys_len = pci_resource_len(pdev, index); > + > + if (!pci_resources_share_page(pdev, index)) > + phys_len = PAGE_ALIGN(phys_len); > + > req_len = vma->vm_end - vma->vm_start; > pgoff = vma->vm_pgoff & > ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);