* Re: [PATCH] video: screen_info: Update framebuffers behind PCI bridges
[not found] <20250417072751.10125-1-tzimmermann@suse.de>
@ 2025-04-22 6:49 ` Thomas Zimmermann
2025-04-22 21:50 ` Javier Martinez Canillas
0 siblings, 1 reply; 2+ messages in thread
From: Thomas Zimmermann @ 2025-04-22 6:49 UTC (permalink / raw)
To: javierm, iivanov; +Cc: dri-devel, stable, open list:PCI SUBSYSTEM
cc'ing PCI devs
Am 17.04.25 um 09:27 schrieb Thomas Zimmermann:
> Apply bridge window offsets to screen_info framebuffers during
> relocation. Fixes invalid access to I/O memory.
>
> Resources behind a PCI bridge can be located at a certain offset
> in the kernel's I/O range. The framebuffer memory range stored in
> screen_info refers to the offset as seen during boot (essentialy 0).
> During boot up, the kernel may assign a different memory offset to
> the bridge device and thereby relocating the framebuffer address of
> the PCI graphics device as seen by the kernel. The information in
> screen_info must be updated as well.
>
> The helper pcibios_bus_to_resource() performs the relocation of
> the screen_info resource. The result now matches the I/O-memory
> resource of the PCI graphics device. As before, we store away the
> information necessary to update the information in screen_info.
>
> Commit 78aa89d1dfba ("firmware/sysfb: Update screen_info for relocated
> EFI framebuffers") added the code for updating screen_info. It is
> based on similar functionality that pre-existed in efifb. But efifb
> did not handle bridges correctly, so the problem presumably exists
> only on newer systems.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Reported-by: Tested-by: "Ivan T. Ivanov" <iivanov@suse.de>
> Closes: https://bugzilla.suse.com/show_bug.cgi?id=1240696
> Tested-by: Tested-by: "Ivan T. Ivanov" <iivanov@suse.de>
> Fixes: 78aa89d1dfba ("firmware/sysfb: Update screen_info for relocated EFI framebuffers")
> Cc: dri-devel@lists.freedesktop.org
> Cc: <stable@vger.kernel.org> # v6.9+
> ---
> drivers/video/screen_info_pci.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/video/screen_info_pci.c b/drivers/video/screen_info_pci.c
> index 6c5833517141..c46c75dc3fae 100644
> --- a/drivers/video/screen_info_pci.c
> +++ b/drivers/video/screen_info_pci.c
> @@ -8,7 +8,7 @@
> static struct pci_dev *screen_info_lfb_pdev;
> static size_t screen_info_lfb_bar;
> static resource_size_t screen_info_lfb_offset;
> -static struct resource screen_info_lfb_res = DEFINE_RES_MEM(0, 0);
> +static struct pci_bus_region screen_info_lfb_region;
>
> static bool __screen_info_relocation_is_valid(const struct screen_info *si, struct resource *pr)
> {
> @@ -31,7 +31,7 @@ void screen_info_apply_fixups(void)
> if (screen_info_lfb_pdev) {
> struct resource *pr = &screen_info_lfb_pdev->resource[screen_info_lfb_bar];
>
> - if (pr->start != screen_info_lfb_res.start) {
> + if (pr->start != screen_info_lfb_region.start) {
> if (__screen_info_relocation_is_valid(si, pr)) {
> /*
> * Only update base if we have an actual
> @@ -69,10 +69,21 @@ static void screen_info_fixup_lfb(struct pci_dev *pdev)
>
> for (i = 0; i < numres; ++i) {
> struct resource *r = &res[i];
> + struct pci_bus_region bus_region = {
> + .start = r->start,
> + .end = r->end,
> + };
> const struct resource *pr;
>
> if (!(r->flags & IORESOURCE_MEM))
> continue;
> +
> + /*
> + * Translate the address to resource if the framebuffer
> + * is behind a PCI bridge.
> + */
> + pcibios_bus_to_resource(pdev->bus, r, &bus_region);
> +
> pr = pci_find_resource(pdev, r);
> if (!pr)
> continue;
> @@ -85,7 +96,7 @@ static void screen_info_fixup_lfb(struct pci_dev *pdev)
> screen_info_lfb_pdev = pdev;
> screen_info_lfb_bar = pr - pdev->resource;
> screen_info_lfb_offset = r->start - pr->start;
> - memcpy(&screen_info_lfb_res, r, sizeof(screen_info_lfb_res));
> + memcpy(&screen_info_lfb_region, &bus_region, sizeof(screen_info_lfb_region));
> }
> }
> DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY, 16,
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
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