| Message ID | 20220214151759.98267-3-hdegoede@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86/PCI: Ignore EFI memmap MMIO entries | expand |
diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c index 9b9fb7882c20..bd501f787a10 100644 --- a/arch/x86/kernel/resource.c +++ b/arch/x86/kernel/resource.c @@ -31,6 +31,10 @@ static void remove_e820_regions(struct resource *avail) for (i = 0; i < e820_table->nr_entries; i++) { entry = &e820_table->entries[i]; + /* Some fw reserves the entire PCI bridge window as MMIO */ + if (entry->type == E820_TYPE_MMIO) + continue; + resource_clip(avail, entry->addr, entry->addr + entry->size - 1); }
Linux excludes E820 reserved addresses when allocating addresses from the PCI host bridge window. This behavior is needed for at least 2 reasons: 1. Some BIOS-es contain a bug where they add addresses which map to system RAM in the PCI host bridge window returned by the ACPI _CRS method, see commit 4dc2287c1805 ("x86: avoid E820 regions when allocating address space"). 2. At least the Lenovo X1 carbon gen 2 BIOS has an overlap between an E820 reserved range and the ACPI _CRS providing the PCI bridge windows: BIOS-e820: [mem 0x00000000dceff000-0x00000000dfa0ffff] reserved pci_bus 0000:00: root bus resource [mem 0xdfa00000-0xfebfffff window] If Linux assigns the overlapping 0xdfa00000-0xdfa0ffff range to a PCI BAR then the system fails to resume after a suspend. Recently (2019) some systems have shown-up with EFI memmap MMIO entries covering the entire _CRS returned PCI bridge memory window. These memmap entries get converted into e820_table entries, causing all attempts to assign memory to PCI BARs which have not been setup by the BIOS to fail. For example see these dmesg snippets from a Lenovo IdeaPad 3 15IIL 81WE: efi: mem63: [MMIO |RUN| | | | | | | | | | | | |UC] range= [0x0000000065400000-0x00000000cfffffff] (1708MB) [mem 0x000000004bc50000-0x00000000cfffffff] reserved pci_bus 0000:00: root bus resource [mem 0x65400000-0xbfffffff window] pci 0000:00:15.0: BAR 0: no space for [mem size 0x00001000 64bit] pci 0000:00:15.0: BAR 0: failed to assign [mem size 0x00001000 64bit] Since the problem is specifically caused by EFI memmap entries with a MMIO type, use the new E820_TYPE_MMIO marking of e820 entries translated from MMIO EFI memmap entries to skip these entries when excluding e820 reservations in arch_remove_reservations(), fixing the problem of not being able to find free space for unassigned BARs. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206459 BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1868899 BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1871793 BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2029207 BugLink: https://bugs.launchpad.net/bugs/1878279 BugLink: https://bugs.launchpad.net/bugs/1931715 BugLink: https://bugs.launchpad.net/bugs/1932069 BugLink: https://bugs.launchpad.net/bugs/1921649 Signed-off-by: Hans de Goede <hdegoede@redhat.com> --- arch/x86/kernel/resource.c | 4 ++++ 1 file changed, 4 insertions(+)