This reverts commit 0cf8882fd06ba0aeb1e90fa6f23fce85504d7e14. Which this commit, with aarch64 when using efi PCI devices with IO ports do not work. The reason is that EFI creates I/O port mappings below 0x1000 (in fact, at 0). However Linux, for legacy reasons, does not support I/O ports <= 0x1000 on PCI, so the I/O assignment created by EFI is rejected.
EFI creates the mappings primarily for itself, and up until DSM #5 started to be enforced, all PCI resource allocations that existed at boot were ignored by Linux and recreated from scratch. Also, the commit in question looks dubious - it seems unlikely that Linux would fail to create a resource tree. What does happen is that BARs get moved around, which may cause trouble in some cases: for instance, Linux had to add special code to the EFI framebuffer driver to copy with framebuffer BARs being relocated. DSM #5 has a long history of debate and misinterpretation. Link: https://lore.kernel.org/r/20210724185234.ga2265...@roeck-us.net/ Fixes: 0cf8882fd06 ("acpi/gpex: Inform os to keep firmware resource map") Reported-by: Guenter Roeck <li...@roeck-us.net> Suggested-by: Ard Biesheuvel <a...@kernel.org> Acked-by: Ard Biesheuvel <a...@kernel.org> Tested-by: Guenter Roeck <li...@roeck-us.net> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- hw/pci-host/gpex-acpi.c | 20 ++------------------ 1 file changed, 2 insertions(+), 18 deletions(-) diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c index 0f01f13a6e..e7e162a00a 100644 --- a/hw/pci-host/gpex-acpi.c +++ b/hw/pci-host/gpex-acpi.c @@ -112,26 +112,10 @@ static void acpi_dsdt_add_pci_osc(Aml *dev) UUID = aml_touuid("E5C937D0-3553-4D7A-9117-EA4D19C3434D"); ifctx = aml_if(aml_equal(aml_arg(0), UUID)); ifctx1 = aml_if(aml_equal(aml_arg(2), aml_int(0))); - uint8_t byte_list[] = { - 0x1 << 0 /* support for functions other than function 0 */ | - 0x1 << 5 /* support for function 5 */ - }; - buf = aml_buffer(ARRAY_SIZE(byte_list), byte_list); + uint8_t byte_list[1] = {1}; + buf = aml_buffer(1, byte_list); aml_append(ifctx1, aml_return(buf)); aml_append(ifctx, ifctx1); - - /* - * PCI Firmware Specification 3.1 - * 4.6.5. _DSM for Ignoring PCI Boot Configurations - */ - /* Arg2: Function Index: 5 */ - ifctx1 = aml_if(aml_equal(aml_arg(2), aml_int(5))); - /* - * 0 - The operating system must not ignore the PCI configuration that - * firmware has done at boot time. - */ - aml_append(ifctx1, aml_return(aml_int(0))); - aml_append(ifctx, ifctx1); aml_append(method, ifctx); byte_list[0] = 0; -- MST
