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,