On Sat, Sep 10, 2022 at 08:11:24PM +0200, Thomas Zimmermann wrote:
> Hi
>
> Am 09.09.22 um 16:43 schrieb Saurabh Sengar:
> >hyperv_setup_vram tries to remove conflicting framebuffer based on
> >'screen_info'. As observed in past due to some bug or wrong setting
> >in grub, the 'screen_info' fields may not be set for Gen1, and in such
> >cases drm_aperture_remove_conflicting_framebuffers will not do anything
> >useful.
> >For Gen1 VMs, it should always be possible to get framebuffer
> >conflict removed using PCI device instead.
> >
> >Fixes: a0ab5abced55 ("drm/hyperv : Removing the restruction of VRAM allocation with PCI bar size")
> >Signed-off-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>
> >---
> > drivers/gpu/drm/hyperv/hyperv_drm_drv.c | 24 ++++++++++++++++++++----
> > 1 file changed, 20 insertions(+), 4 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> >index 6d11e7938c83..b0cc974efa45 100644
> >--- a/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> >+++ b/drivers/gpu/drm/hyperv/hyperv_drm_drv.c
> >@@ -73,12 +73,28 @@ static int hyperv_setup_vram(struct hyperv_drm_device *hv,
> > struct hv_device *hdev)
> > {
> > struct drm_device *dev = &hv->dev;
> >+ struct pci_dev *pdev;
> > int ret;
> >- drm_aperture_remove_conflicting_framebuffers(screen_info.lfb_base,
> >- screen_info.lfb_size,
> >- false,
> >- &hyperv_driver);
> >+ if (efi_enabled(EFI_BOOT)) {
> >+ drm_aperture_remove_conflicting_framebuffers(screen_info.lfb_base,
> >+ screen_info.lfb_size,
>
> Using screen_info here seems wrong in any case. You want to remove
> the framebuffer devices that conflict with your driver, which might
> be unrelated to screen_info. AFAICT the correct solution would
> always retrieve the PCI device for removal (i.e., always do the else
> branch).
In a Gen2 VM, the Hyper-V frame buffer device is presented only as a VMbus device.
It's not presented as a PCI device like it is in a Gen1 VM. This would have worked
if we had the frame buffer device available as PCI device in Gen2 but unfortunately
thats not the case here.
Regards,
Saurabh
>
> Best regard
> Thomas
>
> >+ false,
> >+ &hyperv_driver);
> >+ } 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;
> >+ }
> >+
> >+ ret = drm_aperture_remove_conflicting_pci_framebuffers(pdev, &hyperv_driver);
> >+ pci_dev_put(pdev);
> >+ if (ret) {
> >+ drm_err(dev, "Not able to remove boot fb\n");
> >+ return ret;
> >+ }
> >+ }
> > hv->fb_size = (unsigned long)hv->mmio_megabytes * 1024 * 1024;
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Ivo Totev
