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/** @file
Temporarily enable IO and MMIO decoding for all PCI devices while QEMU
regenerates the ACPI tables.
Copyright (C) 2016-2021, Red Hat, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <Library/DebugLib.h> // DEBUG()
#include <Library/MemoryAllocationLib.h> // AllocatePool()
#include <Library/UefiBootServicesTableLib.h> // gBS
#include "AcpiPlatform.h"
/**
Collect all PciIo protocol instances in the system. Save their original
attributes, and enable IO and MMIO decoding for each.
This is a best effort function; it doesn't return status codes. Its
caller is supposed to proceed even if this function fails.
@param[out] OriginalAttributes On output, a dynamically allocated array of
ORIGINAL_ATTRIBUTES elements. The array lists
the PciIo protocol instances found in the
system at the time of the call, plus the
original PCI attributes for each.
Before returning, the function enables IO and
MMIO decoding for each PciIo instance it
finds.
On error, or when no such instances are
found, OriginalAttributes is set to NULL.
@param[out] Count On output, the number of elements in
OriginalAttributes. On error it is set to
zero.
**/
VOID
EnablePciDecoding (
OUT ORIGINAL_ATTRIBUTES **OriginalAttributes,
OUT UINTN *Count
)
{
EFI_STATUS Status;
UINTN NoHandles;
EFI_HANDLE *Handles;
ORIGINAL_ATTRIBUTES *OrigAttrs;
UINTN Idx;
*OriginalAttributes = NULL;
*Count = 0;
if (PcdGetBool (PcdPciDisableBusEnumeration)) {
//
// The platform downloads ACPI tables from QEMU in general, but there are
// no root bridges in this execution. We're done.
//
return;
}
Status = gBS->LocateHandleBuffer (ByProtocol, &gEfiPciIoProtocolGuid,
NULL /* SearchKey */, &NoHandles, &Handles);
if (Status == EFI_NOT_FOUND) {
//
// No PCI devices were found on either of the root bridges. We're done.
//
return;
}
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_WARN, "%a: LocateHandleBuffer(): %r\n", __FUNCTION__,
Status));
return;
}
OrigAttrs = AllocatePool (NoHandles * sizeof *OrigAttrs);
if (OrigAttrs == NULL) {
DEBUG ((DEBUG_WARN, "%a: AllocatePool(): out of resources\n",
__FUNCTION__));
goto FreeHandles;
}
for (Idx = 0; Idx < NoHandles; ++Idx) {
EFI_PCI_IO_PROTOCOL *PciIo;
UINT64 Attributes;
//
// Look up PciIo on the handle and stash it
//
Status = gBS->HandleProtocol (Handles[Idx], &gEfiPciIoProtocolGuid,
(VOID**)&PciIo);
ASSERT_EFI_ERROR (Status);
OrigAttrs[Idx].PciIo = PciIo;
//
// Stash the current attributes
//
Status = PciIo->Attributes (PciIo, EfiPciIoAttributeOperationGet, 0,
&OrigAttrs[Idx].PciAttributes);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_WARN, "%a: EfiPciIoAttributeOperationGet: %r\n",
__FUNCTION__, Status));
goto RestoreAttributes;
}
//
// Retrieve supported attributes
//
Status = PciIo->Attributes (PciIo, EfiPciIoAttributeOperationSupported, 0,
&Attributes);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_WARN, "%a: EfiPciIoAttributeOperationSupported: %r\n",
__FUNCTION__, Status));
goto RestoreAttributes;
}
//
// Enable IO and MMIO decoding
//
Attributes &= EFI_PCI_IO_ATTRIBUTE_IO | EFI_PCI_IO_ATTRIBUTE_MEMORY;
Status = PciIo->Attributes (PciIo, EfiPciIoAttributeOperationEnable,
Attributes, NULL);
if (EFI_ERROR (Status)) {
DEBUG ((DEBUG_WARN, "%a: EfiPciIoAttributeOperationEnable: %r\n",
__FUNCTION__, Status));
goto RestoreAttributes;
}
}
//
// Success
//
FreePool (Handles);
*OriginalAttributes = OrigAttrs;
*Count = NoHandles;
return;
RestoreAttributes:
while (Idx > 0) {
--Idx;
OrigAttrs[Idx].PciIo->Attributes (OrigAttrs[Idx].PciIo,
EfiPciIoAttributeOperationSet,
OrigAttrs[Idx].PciAttributes,
NULL
);
}
FreePool (OrigAttrs);
FreeHandles:
FreePool (Handles);
}
/**
Restore the original PCI attributes saved with EnablePciDecoding().
@param[in] OriginalAttributes The array allocated and populated by
EnablePciDecoding(). This parameter may be
NULL. If OriginalAttributes is NULL, then the
function is a no-op; otherwise the PciIo
attributes will be restored, and the
OriginalAttributes array will be freed.
@param[in] Count The Count value stored by EnablePciDecoding(),
the number of elements in OriginalAttributes.
Count may be zero if and only if
OriginalAttributes is NULL.
**/
VOID
RestorePciDecoding (
IN ORIGINAL_ATTRIBUTES *OriginalAttributes,
IN UINTN Count
)
{
UINTN Idx;
ASSERT ((OriginalAttributes == NULL) == (Count == 0));
if (OriginalAttributes == NULL) {
return;
}
for (Idx = 0; Idx < Count; ++Idx) {
OriginalAttributes[Idx].PciIo->Attributes (
OriginalAttributes[Idx].PciIo,
EfiPciIoAttributeOperationSet,
OriginalAttributes[Idx].PciAttributes,
NULL
);
}
FreePool (OriginalAttributes);
}
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