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video: screen_info: Relocate framebuffers behind PCI bridges

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commit 2f29b5c231011b94007d2c8a6d793992f2275db1 upstream.

Apply PCI host-bridge window offsets to screen_info framebuffers. Fixes
invalid access to I/O memory.

Resources behind a PCI host bridge can be relocated by a certain offset
in the kernel's CPU address range used for I/O. The framebuffer memory
range stored in screen_info refers to the CPU addresses as seen during
boot (where the offset is 0). During boot up, firmware may assign a
different memory offset to the PCI host bridge 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's framebuffer resource (given in PCI bus addresses). The
result matches the I/O-memory resource of the PCI graphics device (given
in CPU addresses). As before, we store away the information necessary to
later update the information in screen_info itself.

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. Efifb uses a pointer
to the PCI resource, while the newer code does a memcpy of the region.
Hence efifb sees any updates to the PCI resource and avoids the issue.

v3:
- Only use struct pci_bus_region for PCI bus addresses (Bjorn)
- Clarify address semantics in commit messages and comments (Bjorn)
v2:
- Fixed tags (Takashi, Ivan)
- Updated information on efifb

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reported-by: "Ivan T. Ivanov" <iivanov@suse.de>
Closes: https://bugzilla.suse.com/show_bug.cgi?id=1240696
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+
Link: https://lore.kernel.org/r/20250528080234.7380-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Zimmermann
2025-05-28 10:02:08 +02:00
committed by Greg Kroah-Hartman
parent fa2118e9e2
commit cc3cc41ed6
1 changed files with 48 additions and 27 deletions
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59
drivers/video/screen_info_pci.c
View File

@@ -7,8 +7,8 @@
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 resource_size_t screen_info_lfb_res_start; // original start of resource
static resource_size_t screen_info_lfb_offset; // framebuffer offset within resource
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_res_start) {
if (__screen_info_relocation_is_valid(si, pr)) {
/*
* Only update base if we have an actual
@@ -47,35 +47,57 @@ void screen_info_apply_fixups(void)
}
}
static int __screen_info_lfb_pci_bus_region(const struct screen_info *si, unsigned int type,
struct pci_bus_region *r)
{
u64 base, size;
base = __screen_info_lfb_base(si);
if (!base)
return -EINVAL;
size = __screen_info_lfb_size(si, type);
if (!size)
return -EINVAL;
r->start = base;
r->end = base + size - 1;
return 0;
}
static void screen_info_fixup_lfb(struct pci_dev *pdev)
{
unsigned int type;
struct resource res[SCREEN_INFO_MAX_RESOURCES];
size_t i, numres;
struct pci_bus_region bus_region;
int ret;
struct resource r = {
.flags = IORESOURCE_MEM,
};
const struct resource *pr;
const struct screen_info *si = &screen_info;
if (screen_info_lfb_pdev)
return; // already found
type = screen_info_video_type(si);
if (type != VIDEO_TYPE_EFI)
return; // only applies to EFI
if (!__screen_info_has_lfb(type))
return; // only applies to EFI; maybe VESA
ret = screen_info_resources(si, res, ARRAY_SIZE(res));
ret = __screen_info_lfb_pci_bus_region(si, type, &bus_region);
if (ret < 0)
return;
numres = ret;
for (i = 0; i < numres; ++i) {
struct resource *r = &res[i];
const struct resource *pr;
/*
* Translate the PCI bus address to resource. Account
* for an offset if the framebuffer is behind a PCI host
* bridge.
*/
pcibios_bus_to_resource(pdev->bus, &r, &bus_region);
if (!(r->flags & IORESOURCE_MEM))
continue;
pr = pci_find_resource(pdev, r);
pr = pci_find_resource(pdev, &r);
if (!pr)
continue;
return;
/*
* We've found a PCI device with the framebuffer
@@ -84,9 +106,8 @@ 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));
}
screen_info_lfb_offset = r.start - pr->start;
screen_info_lfb_res_start = bus_region.start;
}
DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY, 16,
screen_info_fixup_lfb);