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For the most part, OVMF will clear the encryption bit for MMIO regions, but there is currently one known exception during SEC when the APIC base address is accessed via MMIO with the encryption bit set for SEV-ES/SEV-SNP guests. In the case of SEV-SNP, this requires special handling on the hypervisor side which may not be available in the future[1], so make the necessary changes in the SEC-configured page table to clear the encryption bit for 4K region containing the APIC base address. [1] https://lore.kernel.org/lkml/20240208002420.34mvemnzrwwsaesw@amd.com/#t Suggested-by: Tom Lendacky <thomas.lendacky@amd.com> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Gerd Hoffmann <kraxel@redhat.com> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jianyong Wu <jianyong.wu@arm.com> Cc: Anatol Belski <anbelski@linux.microsoft.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
109 lines
2.3 KiB
C
109 lines
2.3 KiB
C
/** @file
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File defines the Sec routines for the AMD SEV
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Copyright (c) 2021, Advanced Micro Devices, Inc. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#ifndef _AMD_SEV_SEC_INTERNAL_H__
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#define _AMD_SEV_SEC_INTERNAL_H__
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/**
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Handle an SEV-ES/GHCB protocol check failure.
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Notify the hypervisor using the VMGEXIT instruction that the SEV-ES guest
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wishes to be terminated.
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@param[in] ReasonCode Reason code to provide to the hypervisor for the
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termination request.
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**/
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VOID
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SevEsProtocolFailure (
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IN UINT8 ReasonCode
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);
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/**
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Validate the SEV-ES/GHCB protocol level.
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Verify that the level of SEV-ES/GHCB protocol supported by the hypervisor
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and the guest intersect. If they don't intersect, request termination.
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**/
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VOID
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SevEsProtocolCheck (
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VOID
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);
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/**
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Determine if the SEV is active.
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During the early booting, GuestType is set in the work area. Verify that it
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is an SEV guest.
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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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IsSevGuest (
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VOID
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);
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/**
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Determine if SEV-ES is active.
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During early booting, SEV-ES support code will set a flag to indicate that
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SEV-ES is enabled. Return the value of this flag as an indicator that SEV-ES
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is enabled.
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@retval TRUE SEV-ES is enabled
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@retval FALSE SEV-ES is not enabled
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**/
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BOOLEAN
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SevEsIsEnabled (
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VOID
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);
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/**
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Validate System RAM used for decompressing the PEI and DXE firmware volumes
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when SEV-SNP is active. The PCDs SecValidatedStart and SecValidatedEnd are
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set in OvmfPkg/Include/Fdf/FvmainCompactScratchEnd.fdf.inc.
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**/
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VOID
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SecValidateSystemRam (
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VOID
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);
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/**
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Determine if SEV-SNP is active.
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@retval TRUE SEV-SNP is enabled
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@retval FALSE SEV-SNP is not enabled
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**/
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BOOLEAN
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SevSnpIsEnabled (
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VOID
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);
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/**
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Map MMIO regions unencrypted if SEV-ES is active.
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During early booting, page table entries default to having the encryption bit
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set for SEV-ES/SEV-SNP guests. In cases where there is MMIO to an address, the
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encryption bit should be cleared. Clear it here for any known MMIO accesses
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during SEC, which is currently just the APIC base address.
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**/
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VOID
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SecMapApicBaseUnencrypted (
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VOID
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);
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#endif
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