[PATCH 2/2] vfio/pci: Remove console drivers

Alex Williamson
2022-06-06T17:53:39Z

Console drivers can create conflicts with PCI resources resulting in
userspace getting mmap failures to memory BARs. This is especially evident
when trying to re-use the system primary console for userspace drivers.
Attempt to remove all nature of conflicting drivers as part of our VGA
initialization.

Reported-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Suggested-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/pci/vfio_pci_core.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index a0d69ddaf90d..e0cbcbc2aee1 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -13,6 +13,7 @@
#include <linux/device.h>
#include <linux/eventfd.h>
#include <linux/file.h>
+#include <linux/fb.h>
#include <linux/interrupt.h>
#include <linux/iommu.h>
#include <linux/module.h>
@@ -29,6 +30,8 @@

#include <linux/vfio_pci_core.h>

+#include <drm/drm_aperture.h>
+
#define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
#define DRIVER_DESC "core driver for VFIO based PCI devices"

@@ -1793,6 +1796,20 @@ static int vfio_pci_vga_init(struct vfio_pci_core_device *vdev)
if (!vfio_pci_is_vga(pdev))
return 0;

+#if IS_REACHABLE(CONFIG_DRM)
+ drm_aperture_detach_platform_drivers(pdev);
+#endif
+
+#if IS_REACHABLE(CONFIG_FB)
+ ret = remove_conflicting_pci_framebuffers(pdev, vdev->vdev.ops->name);
+ if (ret)
+ return ret;
+#endif
+
+ ret = vga_remove_vgacon(pdev);
+ if (ret)
+ return ret;
+
ret = vga_client_register(pdev, vfio_pci_set_decode);
if (ret)
return ret;