/** @file | |
AMD Sev Dxe driver. This driver is dispatched early in DXE, due to being list | |
in APRIORI. It clears C-bit from MMIO and NonExistent Memory space when SEV | |
is enabled. | |
Copyright (c) 2017 - 2020, AMD Inc. All rights reserved.<BR> | |
SPDX-License-Identifier: BSD-2-Clause-Patent | |
**/ | |
#include <IndustryStandard/Q35MchIch9.h> | |
#include <Library/BaseLib.h> | |
#include <Library/BaseMemoryLib.h> | |
#include <Library/DebugLib.h> | |
#include <Library/DxeServicesTableLib.h> | |
#include <Library/MemEncryptSevLib.h> | |
#include <Library/MemoryAllocationLib.h> | |
#include <Library/PcdLib.h> | |
EFI_STATUS | |
EFIAPI | |
AmdSevDxeEntryPoint ( | |
IN EFI_HANDLE ImageHandle, | |
IN EFI_SYSTEM_TABLE *SystemTable | |
) | |
{ | |
EFI_STATUS Status; | |
EFI_GCD_MEMORY_SPACE_DESCRIPTOR *AllDescMap; | |
UINTN NumEntries; | |
UINTN Index; | |
// | |
// Do nothing when SEV is not enabled | |
// | |
if (!MemEncryptSevIsEnabled ()) { | |
return EFI_UNSUPPORTED; | |
} | |
// | |
// Iterate through the GCD map and clear the C-bit from MMIO and NonExistent | |
// memory space. The NonExistent memory space will be used for mapping the | |
// MMIO space added later (eg PciRootBridge). By clearing both known MMIO and | |
// NonExistent memory space can gurantee that current and furture MMIO adds | |
// will have C-bit cleared. | |
// | |
Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap); | |
if (!EFI_ERROR (Status)) { | |
for (Index = 0; Index < NumEntries; Index++) { | |
CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR *Desc; | |
Desc = &AllDescMap[Index]; | |
if (Desc->GcdMemoryType == EfiGcdMemoryTypeMemoryMappedIo || | |
Desc->GcdMemoryType == EfiGcdMemoryTypeNonExistent) { | |
Status = MemEncryptSevClearPageEncMask ( | |
0, | |
Desc->BaseAddress, | |
EFI_SIZE_TO_PAGES (Desc->Length), | |
FALSE | |
); | |
ASSERT_EFI_ERROR (Status); | |
} | |
} | |
FreePool (AllDescMap); | |
} | |
// | |
// If PCI Express is enabled, the MMCONFIG area has been reserved, rather | |
// than marked as MMIO, and so the C-bit won't be cleared by the above walk | |
// through the GCD map. Check for the MMCONFIG area and clear the C-bit for | |
// the range. | |
// | |
if (PcdGet16 (PcdOvmfHostBridgePciDevId) == INTEL_Q35_MCH_DEVICE_ID) { | |
Status = MemEncryptSevClearPageEncMask ( | |
0, | |
FixedPcdGet64 (PcdPciExpressBaseAddress), | |
EFI_SIZE_TO_PAGES (SIZE_256MB), | |
FALSE | |
); | |
ASSERT_EFI_ERROR (Status); | |
} | |
// | |
// When SMM is enabled, clear the C-bit from SMM Saved State Area | |
// | |
// NOTES: The SavedStateArea address cleared here is before SMBASE | |
// relocation. Currently, we do not clear the SavedStateArea address after | |
// SMBASE is relocated due to the following reasons: | |
// | |
// 1) Guest BIOS never access the relocated SavedStateArea. | |
// | |
// 2) The C-bit works on page-aligned address, but the SavedStateArea | |
// address is not a page-aligned. Theoretically, we could roundup the address | |
// and clear the C-bit of aligned address but looking carefully we found | |
// that some portion of the page contains code -- which will causes a bigger | |
// issues for SEV guest. When SEV is enabled, all the code must be encrypted | |
// otherwise hardware will cause trap. | |
// | |
// We restore the C-bit for this SMM Saved State Area after SMBASE relocation | |
// is completed (See OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c). | |
// | |
if (FeaturePcdGet (PcdSmmSmramRequire)) { | |
UINTN MapPagesBase; | |
UINTN MapPagesCount; | |
Status = MemEncryptSevLocateInitialSmramSaveStateMapPages ( | |
&MapPagesBase, | |
&MapPagesCount | |
); | |
ASSERT_EFI_ERROR (Status); | |
// | |
// Although these pages were set aside (i.e., allocated) by PlatformPei, we | |
// could be after a warm reboot from the OS. Don't leak any stale OS data | |
// to the hypervisor. | |
// | |
ZeroMem ((VOID *)MapPagesBase, EFI_PAGES_TO_SIZE (MapPagesCount)); | |
Status = MemEncryptSevClearPageEncMask ( | |
0, // Cr3BaseAddress -- use current CR3 | |
MapPagesBase, // BaseAddress | |
MapPagesCount, // NumPages | |
TRUE // Flush | |
); | |
if (EFI_ERROR (Status)) { | |
DEBUG ((DEBUG_ERROR, "%a: MemEncryptSevClearPageEncMask(): %r\n", | |
__FUNCTION__, Status)); | |
ASSERT (FALSE); | |
CpuDeadLoop (); | |
} | |
} | |
return EFI_SUCCESS; | |
} |