OvmfPkg/SecMain: validate the memory used for decompressing Fv

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The VMM launch sequence should have pre-validated all the data pages used
in the Reset vector. The range does not cover the data pages used during
the SEC phase (mainly PEI and DXE firmware volume decompression memory).

When SEV-SNP is active, the memory must be pre-validated before the access.
Add support to pre-validate the memory range from SnpSecPreValidatedStart
to SnpSecPreValidatedEnd. This should be sufficent to enter into the PEI
phase.

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: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

8 files changed, 68 insertions, 1 deletions

diff --git a/OvmfPkg/FvmainCompactScratchEnd.fdf.inc b/OvmfPkg/FvmainCompactScratchEnd.fdf.inc
index 46f5258329..d8d45fc9aa 100644
--- a/OvmfPkg/FvmainCompactScratchEnd.fdf.inc
+++ b/OvmfPkg/FvmainCompactScratchEnd.fdf.inc
@@ -63,3 +63,8 @@ DEFINE DECOMP_SCRATCH_BASE_MASK      = 0xFFF00000
 DEFINE DECOMP_SCRATCH_BASE           = (($(DECOMP_SCRATCH_BASE_UNALIGNED) + $(DECOMP_SCRATCH_BASE_ALIGNMENT)) & $(DECOMP_SCRATCH_BASE_MASK))

 

 SET gUefiOvmfPkgTokenSpaceGuid.PcdOvmfDecompressionScratchEnd = $(DECOMP_SCRATCH_BASE) + $(DECOMP_SCRATCH_SIZE)

+

+#

+# The range of pages that should be pre-validated during the SEC phase when SEV-SNP is active in the guest VM.

+SET gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart = $(MEMFD_BASE_ADDRESS) + gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase

+SET gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd = $(DECOMP_SCRATCH_BASE) + $(DECOMP_SCRATCH_SIZE)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
index 49d5bd1bef..50c83859d7 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
@@ -60,3 +60,5 @@
   gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecPageTablesBase

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
index 0e3eba3c51..4970165444 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiSnpSystemRamValidate.c
@@ -29,6 +29,11 @@ STATIC SNP_PRE_VALIDATED_RANGE  mPreValidatedRange[] = {
     FixedPcdGet32 (PcdOvmfSecPageTablesBase),

     FixedPcdGet32 (PcdOvmfPeiMemFvBase),

   },

+  // The below range is pre-validated by the Sec/SecMain.c

+  {

+    FixedPcdGet32 (PcdOvmfSecValidatedStart),

+    FixedPcdGet32 (PcdOvmfSecValidatedEnd)

+  },

 };

 

 STATIC

diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
index bc14cf2ed4..c22b846cd6 100644
--- a/OvmfPkg/OvmfPkg.dec
+++ b/OvmfPkg/OvmfPkg.dec
@@ -364,6 +364,10 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidBase|0|UINT32|0x60

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfCpuidSize|0|UINT32|0x61

 

+  ## The range of memory that is validated by the SEC phase.

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart|0|UINT32|0x62

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd|0|UINT32|0x63

+

 [PcdsDynamic, PcdsDynamicEx]

   gUefiOvmfPkgTokenSpaceGuid.PcdEmuVariableEvent|0|UINT64|2

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfFlashVariablesEnable|FALSE|BOOLEAN|0x10

diff --git a/OvmfPkg/Sec/AmdSev.c b/OvmfPkg/Sec/AmdSev.c
index aa655fd9cb..499d0c27d8 100644
--- a/OvmfPkg/Sec/AmdSev.c
+++ b/OvmfPkg/Sec/AmdSev.c
@@ -55,7 +55,6 @@ SevEsProtocolFailure (
   @retval FALSE  SEV-SNP is not enabled

 

 **/

-STATIC

 BOOLEAN

 SevSnpIsEnabled (

   VOID

@@ -281,3 +280,24 @@ SevEsIsEnabled (
 

   return (SevEsWorkArea->SevEsEnabled != 0);

 }

+

+/**

+ Validate System RAM used for decompressing the PEI and DXE firmware volumes

+ when SEV-SNP is active. The PCDs SecValidatedStart and SecValidatedEnd are

+ set in OvmfPkg/FvmainCompactScratchEnd.fdf.inc.

+

+**/

+VOID

+SecValidateSystemRam (

+  VOID

+  )

+{

+  PHYSICAL_ADDRESS  Start, End;

+

+  if (IsSevGuest () && SevSnpIsEnabled ()) {

+    Start = (EFI_PHYSICAL_ADDRESS)(UINTN)PcdGet32 (PcdOvmfSecValidatedStart);

+    End   = (EFI_PHYSICAL_ADDRESS)(UINTN)PcdGet32 (PcdOvmfSecValidatedEnd);

+

+    MemEncryptSevSnpPreValidateSystemRam (Start, EFI_SIZE_TO_PAGES ((UINTN)(End - Start)));

+  }

+}

diff --git a/OvmfPkg/Sec/AmdSev.h b/OvmfPkg/Sec/AmdSev.h
index c0b1ca9618..dffd2ceb96 100644
--- a/OvmfPkg/Sec/AmdSev.h
+++ b/OvmfPkg/Sec/AmdSev.h
@@ -68,4 +68,27 @@ SevEsIsEnabled (
   VOID

   );

 

+/**

+ Validate System RAM used for decompressing the PEI and DXE firmware volumes

+ when SEV-SNP is active. The PCDs SecValidatedStart and SecValidatedEnd are

+ set in OvmfPkg/FvmainCompactScratchEnd.fdf.inc.

+

+**/

+VOID

+SecValidateSystemRam (

+  VOID

+  );

+

+/**

+  Determine if SEV-SNP is active.

+

+  @retval TRUE   SEV-SNP is enabled

+  @retval FALSE  SEV-SNP is not enabled

+

+**/

+BOOLEAN

+SevSnpIsEnabled (

+  VOID

+  );

+

 #endif

diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index 58e3b923b4..2c5561661e 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -861,6 +861,11 @@ SecCoreStartupWithStack (
   SecCoreData.BootFirmwareVolumeSize = (UINTN)BootFv->FvLength;

 

   //

+  // Validate the System RAM used in the SEC Phase

+  //

+  SecValidateSystemRam ();

+

+  //

   // Make sure the 8259 is masked before initializing the Debug Agent and the debug timer is enabled

   //

   IoWrite8 (0x21, 0xff);

diff --git a/OvmfPkg/Sec/SecMain.inf b/OvmfPkg/Sec/SecMain.inf
index 41dcdba120..95cf0025e1 100644
--- a/OvmfPkg/Sec/SecMain.inf
+++ b/OvmfPkg/Sec/SecMain.inf
@@ -52,6 +52,7 @@
   PeCoffExtraActionLib

   ExtractGuidedSectionLib

   LocalApicLib

+  MemEncryptSevLib

   CpuExceptionHandlerLib

 

 [Ppis]

@@ -74,6 +75,8 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdInitValueInTempStack

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfConfidentialComputingWorkAreaHeader

   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedStart

+  gUefiOvmfPkgTokenSpaceGuid.PcdOvmfSecValidatedEnd

 

 [FeaturePcd]

   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire