Re: [PATCH 6.0 20/20] fbdev/core: Remove remove_conflicting_pci_framebuffers()

Boris V.
2022-11-01T08:48:35Z

On 24/10/2022 13:31, Greg Kroah-Hartman wrote:
> From: Thomas Zimmermann <tzimmermann@suse.de>
>
> commit 9d69ef1838150c7d87afc1a87aa658c637217585 upstream.
>
> Remove remove_conflicting_pci_framebuffers() and implement similar
> functionality in aperture_remove_conflicting_pci_device(), which was
> the only caller. Removes an otherwise unused interface and streamlines
> the aperture helper. No functional changes.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
> Link: https://patchwork.freedesktop.org/patch/msgid/20220718072322.8927-5-tzimmermann@suse.de
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> drivers/video/aperture.c | 30 ++++++++++++++----------
> drivers/video/fbdev/core/fbmem.c | 48 ---------------------------------------
> include/linux/fb.h | 2 -
> 3 files changed, 18 insertions(+), 62 deletions(-)
>
> --- a/drivers/video/aperture.c
> +++ b/drivers/video/aperture.c
> @@ -335,30 +335,36 @@ EXPORT_SYMBOL(aperture_remove_conflictin
> */
> int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *name)
> {
> + bool primary = false;
> resource_size_t base, size;
> int bar, ret;
>
> - /*
> - * WARNING: Apparently we must kick fbdev drivers before vgacon,
> - * otherwise the vga fbdev driver falls over.
> - */
> -#if IS_REACHABLE(CONFIG_FB)
> - ret = remove_conflicting_pci_framebuffers(pdev, name);
> - if (ret)
> - return ret;
> +#ifdef CONFIG_X86
> + primary = pdev->resource[PCI_ROM_RESOURCE].flags & IORESOURCE_ROM_SHADOW;
> #endif
> - ret = vga_remove_vgacon(pdev);
> - if (ret)
> - return ret;
>
> for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) {
> if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> continue;
> +
> base = pci_resource_start(pdev, bar);
> size = pci_resource_len(pdev, bar);
> - aperture_detach_devices(base, size);
> + ret = aperture_remove_conflicting_devices(base, size, primary, name);
> + if (ret)
> + break;
> }
>
> + if (ret)
> + return ret;
> +
> + /*
> + * WARNING: Apparently we must kick fbdev drivers before vgacon,
> + * otherwise the vga fbdev driver falls over.
> + */
> + ret = vga_remove_vgacon(pdev);
> + if (ret)
> + return ret;
> +
> return 0;
>
> }
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1788,54 +1788,6 @@ int remove_conflicting_framebuffers(stru
> EXPORT_SYMBOL(remove_conflicting_framebuffers);
>
> /**
> - * remove_conflicting_pci_framebuffers - remove firmware-configured framebuffers for PCI devices
> - * @pdev: PCI device
> - * @name: requesting driver name
> - *
> - * This function removes framebuffer devices (eg. initialized by firmware)
> - * using memory range configured for any of @pdev's memory bars.
> - *
> - * The function assumes that PCI device with shadowed ROM drives a primary
> - * display and so kicks out vga16fb.
> - */
> -int remove_conflicting_pci_framebuffers(struct pci_dev *pdev, const char *name)
> -{
> - struct apertures_struct *ap;
> - bool primary = false;
> - int err, idx, bar;
> -
> - for (idx = 0, bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> - if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> - continue;
> - idx++;
> - }
> -
> - ap = alloc_apertures(idx);
> - if (!ap)
> - return -ENOMEM;
> -
> - for (idx = 0, bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> - if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> - continue;
> - ap->ranges[idx].base = pci_resource_start(pdev, bar);
> - ap->ranges[idx].size = pci_resource_len(pdev, bar);
> - pci_dbg(pdev, "%s: bar %d: 0x%lx -> 0x%lx\n", __func__, bar,
> - (unsigned long)pci_resource_start(pdev, bar),
> - (unsigned long)pci_resource_end(pdev, bar));
> - idx++;
> - }
> -
> -#ifdef CONFIG_X86
> - primary = pdev->resource[PCI_ROM_RESOURCE].flags &
> - IORESOURCE_ROM_SHADOW;
> -#endif
> - err = remove_conflicting_framebuffers(ap, name, primary);
> - kfree(ap);
> - return err;
> -}
> -EXPORT_SYMBOL(remove_conflicting_pci_framebuffers);
> -
> -/**
> * register_framebuffer - registers a frame buffer device
> * @fb_info: frame buffer info structure
> *
> --- a/include/linux/fb.h
> +++ b/include/linux/fb.h
> @@ -615,8 +615,6 @@ extern ssize_t fb_sys_write(struct fb_in
> /* drivers/video/fbmem.c */
> extern int register_framebuffer(struct fb_info *fb_info);
> extern void unregister_framebuffer(struct fb_info *fb_info);
> -extern int remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
> - const char *name);
> extern int remove_conflicting_framebuffers(struct apertures_struct *a,
> const char *name, bool primary);
> extern int fb_prepare_logo(struct fb_info *fb_info, int rotate);
>
>
>
>

Hello,

this patch seems to disable console/framebuffer when vfio-pci is used.
I hava 2 nvidia GPUs one is used for host and other is passed through to VM.
Now after this patch, when vfio-pci module is loaded with parameter
ids=10de:2486,10de:228b,
console is lost/frozen, last message is that vfio-pci module was loaded
and then there is no more output.
This PCI IDs (10de:2486,10de:228b) are for secondary GPU, primary/boot
GPU is used for host and boot messages are displayed on primary/boot GPU.

Using dmesg I see this messages after vfio-pci is loaded:

[    3.993601] VFIO - User Level meta-driver version: 0.3
[    4.020239] Console: switching to colour dummy device 80x25
[    4.020335] vfio-pci 0000:1a:00.0: vgaarb: changed VGA decodes:
olddecodes=io+mem,decodes=none:owns=none
[    4.020722] vfio_pci: add [10de:2486[ffffffff:ffffffff]] class
0x000000/00000000
[    4.116616] vfio_pci: add [10de:228b[ffffffff:ffffffff]] class
0x000000/00000000

I guess the problem here is "Console: switching to colour dummy device
80x25", but I don't know why this happens.
Last working kernel is 6.0.3, after upgrading to 6.0.4 (and 6.0.5,
6.0.6), console is no longer working.
By git bisecting it seems bad commit is
af9ac541e88390d97b01d5e8c77309d2637c1d4c.