d706f8fec2
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275 Virtual Machine Privilege Level (VMPL) feature in the SEV-SNP architecture allows a guest VM to divide its address space into four levels. The level can be used to provide the hardware isolated abstraction layers with a VM. The VMPL0 is the highest privilege, and VMPL3 is the least privilege. Certain operations must be done by the VMPL0 software, such as: * Validate or invalidate memory range (PVALIDATE instruction) * Allocate VMSA page (RMPADJUST instruction when VMSA=1) The initial SEV-SNP support assumes that the guest is running on VMPL0. Let's add function in the MemEncryptSevLib that can be used for checking whether guest is booted under the VMPL0. Cc: Michael Roth <michael.roth@amd.com> Cc: James Bottomley <jejb@linux.ibm.com> Cc: Min Xu <min.m.xu@intel.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Erdem Aktas <erdemaktas@google.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
83 lines
1.8 KiB
C
83 lines
1.8 KiB
C
/** @file
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SEV-SNP Page Validation functions.
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Copyright (c) 2021 AMD Incorporated. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <Uefi/UefiBaseType.h>
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#include <Library/BaseLib.h>
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#include <Library/MemEncryptSevLib.h>
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#include "SnpPageStateChange.h"
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//
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// The variable used for the VMPL check.
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//
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STATIC UINT8 gVmpl0Data[4096];
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/**
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The function checks whether SEV-SNP guest is booted under VMPL0.
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@retval TRUE The guest is booted under VMPL0
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@retval FALSE The guest is not booted under VMPL0
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**/
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STATIC
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BOOLEAN
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SevSnpIsVmpl0 (
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VOID
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)
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{
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UINT64 Rdx;
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EFI_STATUS Status;
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//
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// There is no straightforward way to query the current VMPL level.
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// The simplest method is to use the RMPADJUST instruction to change
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// a page permission to a VMPL level-1, and if the guest kernel is
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// launched at a level <= 1, then RMPADJUST instruction will return
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// an error.
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//
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Rdx = 1;
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Status = AsmRmpAdjust ((UINT64)gVmpl0Data, 0, Rdx);
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if (EFI_ERROR (Status)) {
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return FALSE;
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}
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return TRUE;
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}
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/**
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Pre-validate the system RAM when SEV-SNP is enabled in the guest VM.
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@param[in] BaseAddress Base address
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@param[in] NumPages Number of pages starting from the base address
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**/
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VOID
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EFIAPI
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MemEncryptSevSnpPreValidateSystemRam (
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IN PHYSICAL_ADDRESS BaseAddress,
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IN UINTN NumPages
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)
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{
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if (!MemEncryptSevSnpIsEnabled ()) {
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return;
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}
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//
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// The page state change uses the PVALIDATE instruction. The instruction
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// can be run on VMPL-0 only. If its not VMPL-0 guest then terminate
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// the boot.
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//
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if (!SevSnpIsVmpl0 ()) {
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SnpPageStateFailureTerminate ();
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}
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InternalSetPageState (BaseAddress, NumPages, SevSnpPagePrivate, TRUE);
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}
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