Re: [RFC PATCH v4 5/7] vfio-pci: Allow to mmap sub-page MMIO BARs if the mmio page is exclusive

[Yongji Xie]

On 2016/3/17 0:30, Alex Williamson wrote:
> 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)) {

OK. I'll fix it.

Thanks,
Yongji Xie