On Mon, 7 Mar 2016 15:48:36 +0800
Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx> 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 <xyjxie@xxxxxxxxxxxxxxxxxx>
> ---
> 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);
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