qxl has two modes: "native" (used by the drm driver) and "vga" (vga compatibility mode, typically used for boot display and firmware framebuffers).

Accessing any vga ioport will switch the qxl device into vga mode. The qxl driver never does that, but other drivers accessing vga ports can trigger that too and therefore disturb qxl operation. So aquire the legacy vga ioports from vgaarb to avoid that.

Reporducer: Boot kvm guest with both qxl and i915 vgpu, with qxl being

typo: "Reporducer"

first in pci scan order.

Signed-off-by: Gerd Hoffmann kraxel@redhat.com

drivers/gpu/drm/qxl/qxl_drv.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c index b57a37543613..8a2e86adc423 100644 --- a/drivers/gpu/drm/qxl/qxl_drv.c +++ b/drivers/gpu/drm/qxl/qxl_drv.c @@ -87,9 +87,15 @@ qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent) if (ret) goto disable_pci;

• ret = vga_get_interruptible(pdev, VGA_RSRC_LEGACY_IO);
• if (ret) {

• DRM_ERROR("can't get legacy vga ports\n");
  

• goto put_vga;
  

I suppose that if this fails it's secondary so should continue. What happen configuring 2 QXL devices? Only a card should provide VGA registers in the system so if any other card provide them QXL won't work.

• }
• ret = qxl_device_init(qdev, &qxl_driver, pdev); if (ret)

• goto disable_pci;
  

• goto put_vga;
  
  

  ret = qxl_modeset_init(qdev); if (ret)

@@ -109,6 +115,8 @@ qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent) qxl_modeset_fini(qdev); unload: qxl_device_fini(qdev); +put_vga:

• vga_put(pdev, VGA_RSRC_LEGACY_IO);

What happen if you didn't get the I/O? Maybe it's safe to just call vga_put and avoid adding an additional label here?

disable_pci: pci_disable_device(pdev); free_dev: @@ -126,6 +134,7 @@ qxl_pci_remove(struct pci_dev *pdev)

qxl_modeset_fini(qdev); qxl_device_fini(qdev);

• vga_put(pdev, VGA_RSRC_LEGACY_IO);

  dev->dev_private = NULL; kfree(qdev);

Frediano