On 2016/1/29 6:46, Alex Williamson wrote:

On Fri, 2016-01-15 at 15:06 +0800, Yongji Xie wrote:

quoted

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 <redacted>
---
  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