Re: [RFC PATCH v3 5/5] vfio-pci: Allow to mmap MSI-X table if host bridge supports filtering of MSIs

[Yongji Xie]

On 2016/1/29 6:46, Alex Williamson wrote:
> On Fri, 2016-01-15 at 15:06 +0800, Yongji Xie wrote:
> > Current vfio-pci implementation disallows to mmap MSI-X
> > table in case that user get to touch this directly.
> >   
> > But we should allow to mmap these MSI-X tables if the PCI
> > host bridge supports filtering of MSIs.
> >   
> > Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/vfio/pci/vfio_pci.c |    6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >   
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index 11fd0f0..4d68f6a 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -555,7 +555,8 @@ static long vfio_pci_ioctl(void *device_data,
> >   			    IORESOURCE_MEM && !pci_resources_share_page(pdev,
> >   			    info.index)) {
> >   				info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
> > -				if (info.index == vdev->msix_bar) {
> > +				if (!pci_host_bridge_msi_filtered_enabled(pdev) &&
> > +				    info.index == vdev->msix_bar) {
> >   					ret = msix_sparse_mmap_cap(vdev, &caps);
> >   					if (ret)
> >   						return ret;
> > @@ -967,7 +968,8 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
> >   	if (phys_len < PAGE_SIZE || req_start + req_len > phys_len)
> >   		return -EINVAL;
> >   
> > -	if (index == vdev->msix_bar) {
> > +	if (!pci_host_bridge_msi_filtered_enabled(pdev) &&
> > +	    index == vdev->msix_bar) {
> >   		/*
> >   		 * Disallow mmaps overlapping the MSI-X table; users don't
> >   		 * get to touch this directly.  We could find somewhere
> What about read()/write() access, why would we allow mmap() but not
> those?

Yes, you are right! I miss the MSI-X table check in vfio_pci_bar_rw().
I will fix it in next version. Thanks.

Regards,
Yongji Xie