61a044c6c1
In the next three patches, we're going to modify three modules under OvmfPkg. When OVMF is built with -D SMM_REQUIRE and runs in an SEV guest, each affected module will have to know the page range that covers the initial (pre-SMBASE relocation) SMRAM save state map. Add a helper function to MemEncryptSevLib that calculates the "base address" and "number of pages" constants for this page range. (In a RELEASE build -- i.e., with assertions disabled and optimization enabled --, the helper function can be compiled to store two constants determined at compile time.) Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Tested-by: Brijesh Singh <brijesh.singh@amd.com> Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
141 lines
3.7 KiB
C
141 lines
3.7 KiB
C
/** @file
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Secure Encrypted Virtualization (SEV) library helper function
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Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
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This program and the accompanying materials are licensed and made available
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under the terms and conditions of the BSD License which accompanies this
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distribution. The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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#include <Library/BaseLib.h>
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#include <Library/DebugLib.h>
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#include <Library/MemEncryptSevLib.h>
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#include <Library/PcdLib.h>
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#include <Register/Amd/Cpuid.h>
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#include <Register/Amd/Msr.h>
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#include <Register/Cpuid.h>
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#include <Register/QemuSmramSaveStateMap.h>
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#include <Register/SmramSaveStateMap.h>
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#include <Uefi/UefiBaseType.h>
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STATIC BOOLEAN mSevStatus = FALSE;
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STATIC BOOLEAN mSevStatusChecked = FALSE;
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/**
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Returns a boolean to indicate whether SEV is enabled
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@retval TRUE SEV is enabled
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@retval FALSE SEV is not enabled
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**/
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STATIC
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BOOLEAN
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EFIAPI
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InternalMemEncryptSevIsEnabled (
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VOID
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)
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{
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UINT32 RegEax;
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MSR_SEV_STATUS_REGISTER Msr;
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CPUID_MEMORY_ENCRYPTION_INFO_EAX Eax;
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//
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// Check if memory encryption leaf exist
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//
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AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
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if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
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//
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// CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
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//
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AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
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if (Eax.Bits.SevBit) {
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//
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// Check MSR_0xC0010131 Bit 0 (Sev Enabled)
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//
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Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
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if (Msr.Bits.SevBit) {
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return TRUE;
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}
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}
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}
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return FALSE;
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}
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/**
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Returns a boolean to indicate whether SEV is enabled
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@retval TRUE SEV is enabled
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@retval FALSE SEV is not enabled
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**/
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BOOLEAN
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EFIAPI
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MemEncryptSevIsEnabled (
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VOID
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)
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{
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if (mSevStatusChecked) {
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return mSevStatus;
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}
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mSevStatus = InternalMemEncryptSevIsEnabled();
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mSevStatusChecked = TRUE;
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return mSevStatus;
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}
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/**
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Locate the page range that covers the initial (pre-SMBASE-relocation) SMRAM
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Save State Map.
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@param[out] BaseAddress The base address of the lowest-address page that
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covers the initial SMRAM Save State Map.
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@param[out] NumberOfPages The number of pages in the page range that covers
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the initial SMRAM Save State Map.
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@retval RETURN_SUCCESS BaseAddress and NumberOfPages have been set on
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output.
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@retval RETURN_UNSUPPORTED SMM is unavailable.
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**/
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RETURN_STATUS
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EFIAPI
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MemEncryptSevLocateInitialSmramSaveStateMapPages (
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OUT UINTN *BaseAddress,
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OUT UINTN *NumberOfPages
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)
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{
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UINTN MapStart;
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UINTN MapEnd;
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UINTN MapPagesStart; // MapStart rounded down to page boundary
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UINTN MapPagesEnd; // MapEnd rounded up to page boundary
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UINTN MapPagesSize; // difference between MapPagesStart and MapPagesEnd
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if (!FeaturePcdGet (PcdSmmSmramRequire)) {
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return RETURN_UNSUPPORTED;
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}
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MapStart = SMM_DEFAULT_SMBASE + SMRAM_SAVE_STATE_MAP_OFFSET;
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MapEnd = MapStart + sizeof (QEMU_SMRAM_SAVE_STATE_MAP);
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MapPagesStart = MapStart & ~(UINTN)EFI_PAGE_MASK;
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MapPagesEnd = ALIGN_VALUE (MapEnd, EFI_PAGE_SIZE);
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MapPagesSize = MapPagesEnd - MapPagesStart;
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ASSERT ((MapPagesSize & EFI_PAGE_MASK) == 0);
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*BaseAddress = MapPagesStart;
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*NumberOfPages = MapPagesSize >> EFI_PAGE_SHIFT;
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return RETURN_SUCCESS;
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}
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