From 40c3472a29c9a1fd65255fc196aa6feb99aaec9e Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 27 Jul 2021 05:18:47 -0400 Subject: [PATCH] Revert "acpi/gpex: Inform os to keep firmware resource map" 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.GA2265457@roeck-us.net/ Fixes: 0cf8882fd06 ("acpi/gpex: Inform os to keep firmware resource map") Reported-by: Guenter Roeck Suggested-by: Ard Biesheuvel Acked-by: Ard Biesheuvel Tested-by: Guenter Roeck Signed-off-by: Michael S. Tsirkin --- 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;