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Revert "acpi/gpex: Inform os to keep firmware resource map"

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This reverts commit 0cf8882fd0.

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: 0cf8882fd0 ("acpi/gpex: Inform os to keep firmware resource map")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2021-07-27 05:18:47 -04:00
parent 5cd4a8d4e5
commit 40c3472a29
1 changed files with 2 additions and 18 deletions
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20
hw/pci-host/gpex-acpi.c
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@ -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;