[RFC v5 7/7] vfio-pci: Allow to mmap MSI-X table if interrupt remapping is supported

[Yongji Xie]

This patch enables mmapping MSI-X tables if
hardware supports interrupt remapping which
can ensure that a given pci device can only
shoot the MSIs assigned for it.

Signed-off-by: Yongji Xie <xyjxie at linux.vnet.ibm.com>
---
 drivers/vfio/pci/vfio_pci.c         |    9 +++++++--
 drivers/vfio/pci/vfio_pci_private.h |    1 +
 drivers/vfio/pci/vfio_pci_rdwr.c    |    2 +-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index c60d790..ef02896 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -201,6 +201,10 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
 	} else
 		vdev->msix_bar = 0xFF;
 
+	if (iommu_capable(pdev->dev.bus, IOMMU_CAP_INTR_REMAP) ||
+		pdev->bus->bus_flags | PCI_BUS_FLAGS_MSI_REMAP)
+		vdev->msi_remap = true;
+
 	if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
 		vdev->has_vga = true;
 
@@ -635,7 +639,8 @@ static long vfio_pci_ioctl(void *device_data,
 				     VFIO_REGION_INFO_FLAG_WRITE;
 			if (vdev->bar_mmap_supported[info.index]) {
 				info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
-				if (info.index == vdev->msix_bar) {
+				if (info.index == vdev->msix_bar &&
+						!vdev->msi_remap) {
 					ret = msix_sparse_mmap_cap(vdev, &caps);
 					if (ret)
 						return ret;
@@ -1067,7 +1072,7 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
 	if (req_start + req_len > phys_len)
 		return -EINVAL;
 
-	if (index == vdev->msix_bar) {
+	if (index == vdev->msix_bar && !vdev->msi_remap) {
 		/*
 		 * Disallow mmaps overlapping the MSI-X table; users don't
 		 * get to touch this directly.  We could find somewhere
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 0ea4c62..4f20963 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -78,6 +78,7 @@ struct vfio_pci_device {
 	int			irq_type;
 	int			num_regions;
 	struct vfio_pci_region	*region;
+	bool			msi_remap;
 	u8			msi_qmax;
 	u8			msix_bar;
 	u16			msix_size;
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 5ffd1d9..606ee3c 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -164,7 +164,7 @@ ssize_t vfio_pci_bar_rw(struct vfio_pci_device *vdev, char __user *buf,
 	} else
 		io = vdev->barmap[bar];
 
-	if (bar == vdev->msix_bar) {
+	if (bar == vdev->msix_bar && !vdev->msi_remap) {
 		x_start = vdev->msix_offset;
 		x_end = vdev->msix_offset + vdev->msix_size;
 	}
-- 
1.7.9.5