From: Mohammed Gamal mgamal@redhat.com
[ Upstream commit e048834c209a02e3776bcc47d43c6d863e3a67ca ]
The Hyper-V DRM driver tries to free MMIO region on removing the device regardless of VM type, while Gen1 VMs don't use MMIO and hence causing the kernel to crash on a NULL pointer dereference.
Fix this by making deallocating MMIO only on Gen2 machines and implement removal for Gen1
Fixes: 76c56a5affeb ("drm/hyperv: Add DRM driver for hyperv synthetic video device")
Signed-off-by: Mohammed Gamal mgamal@redhat.com Reviewed-by: Deepak Rawat drawat.floss@gmail.com Signed-off-by: Deepak Rawat drawat.floss@gmail.com Link: https://patchwork.freedesktop.org/patch/msgid/20211119112900.300537-1-mgamal... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c index cd818a6291835..00e53de4812bb 100644 --- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c +++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c @@ -225,12 +225,29 @@ static int hyperv_vmbus_remove(struct hv_device *hdev) { struct drm_device *dev = hv_get_drvdata(hdev); struct hyperv_drm_device *hv = to_hv(dev); + struct pci_dev *pdev;
drm_dev_unplug(dev); drm_atomic_helper_shutdown(dev); vmbus_close(hdev->channel); hv_set_drvdata(hdev, NULL); - vmbus_free_mmio(hv->mem->start, hv->fb_size); + + /* + * Free allocated MMIO memory only on Gen2 VMs. + * On Gen1 VMs, release the PCI device + */ + if (efi_enabled(EFI_BOOT)) { + vmbus_free_mmio(hv->mem->start, hv->fb_size); + } else { + pdev = pci_get_device(PCI_VENDOR_ID_MICROSOFT, + PCI_DEVICE_ID_HYPERV_VIDEO, NULL); + if (!pdev) { + drm_err(dev, "Unable to find PCI Hyper-V video\n"); + return -ENODEV; + } + pci_release_region(pdev, 0); + pci_dev_put(pdev); + }
return 0; }