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Bjorn Helgaas authored
Firmware can use EfiMemoryMappedIO to request that MMIO regions be mapped by the OS so they can be accessed by EFI runtime services, but should have no other significance to the OS (UEFI r2.10, sec 7.2). However, most bootloaders and EFI stubs convert EfiMemoryMappedIO regions to E820_TYPE_RESERVED entries, which prevent Linux from allocating space from them (see remove_e820_regions()). Some platforms use EfiMemoryMappedIO entries for PCI MMCONFIG space and PCI host bridge windows, which means Linux can't allocate BAR space for hot-added devices. Remove large EfiMemoryMappedIO regions from the E820 map to avoid this problem. Leave small (< 256KB) EfiMemoryMappedIO regions alone because on some platforms, these describe non-window space that's included in host bridge _CRS. If we assign that space to PCI devices, they don't work. On the Lenovo X1 Carbon, this leads to suspend/resume failures. The previous solution to the problem of allocating BARs in these regions was to add pci_crs_quirks[] entries to disable E820 checking for these machines (see d341838d ("x86/PCI: Disable E820 reserved region clipping via quirks")): Acer DMI_PRODUCT_NAME Spin SP513-54N Clevo DMI_BOARD_NAME X170KM-G Lenovo DMI_PRODUCT_VERSION *IIL* Florent reported the BAR allocation issue on the Clevo NL4XLU. We could add another quirk for the NL4XLU, but I hope this generic change can solve it for many machines without having to add quirks. This change has been tested on Clevo X170KM-G (Konrad) and Lenovo Ideapad Slim 3 (Matt) and solves the problem even when overriding the existing quirks by booting with "pci=use_e820". Link: https://bugzilla.kernel.org/show_bug.cgi?id=216565 Clevo NL4XLU Link: https://bugzilla.kernel.org/show_bug.cgi?id=206459#c78 Clevo X170KM-G Link: https://bugzilla.redhat.com/show_bug.cgi?id=1868899 Ideapad Slim 3 Link: https://bugzilla.redhat.com/show_bug.cgi?id=2029207 X1 Carbon Link: https://lore.kernel.org/r/20221208190341.1560157-2-helgaas@kernel.orgReported-by:
Florent DELAHAYE <kernelorg@undead.fr> Tested-by:
Konrad J Hambrick <kjhambrick@gmail.com> Tested-by:
Matt Hansen <2lprbe78@duck.com> Signed-off-by:
Bjorn Helgaas <bhelgaas@google.com> Acked-by:
Hans de Goede <hdegoede@redhat.com>
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