OvmfPkg/SmmAccess: close and lock SMRAM at default SMBASE

During normal boot, when EFI_DXE_SMM_READY_TO_LOCK_PROTOCOL is installed
by platform BDS, the SMM IPL locks SMRAM (TSEG) through
EFI_SMM_ACCESS2_PROTOCOL.Lock(). See SmmIplReadyToLockEventNotify() in
"MdeModulePkg/Core/PiSmmCore/PiSmmIpl.c".

During S3 resume, S3Resume2Pei locks SMRAM (TSEG) through
PEI_SMM_ACCESS_PPI.Lock(), before executing the boot script. See
S3ResumeExecuteBootScript() in
"UefiCpuPkg/Universal/Acpi/S3Resume2Pei/S3Resume.c".

Those are precisely the places where the SMRAM at the default SMBASE
should be locked too. Add such an action to SmramAccessLock().

Notes:

- The SMRAM at the default SMBASE doesn't support the "closed and
  unlocked" state (and so it can't be closed without locking it, and it
  cannot be opened after closing it).

- The SMRAM at the default SMBASE isn't (and shouldn't) be exposed with
  another EFI_SMRAM_DESCRIPTOR in the GetCapabilities() members of
  EFI_SMM_ACCESS2_PROTOCOL / PEI_SMM_ACCESS_PPI. That's because the SMRAM
  in question is not "general purpose"; it's only QEMU's solution to
  protect the initial SMI handler from the OS, when a VCPU is hot-plugged.

  Consequently, the state of the SMRAM at the default SMBASE is not
  reflected in the "OpenState" / "LockState" fields of the protocol and
  PPI.

- An alternative to extending SmramAccessLock() would be to register an
  EFI_DXE_SMM_READY_TO_LOCK_PROTOCOL notify in SmmAccess2Dxe (for locking
  at normal boot), and an EDKII_S3_SMM_INIT_DONE_GUID PPI notify in
  SmmAccessPei (for locking at S3 resume).

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Message-Id: <20200129214412.2361-10-lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

6 files changed, 48 insertions, 0 deletions

diff --git a/OvmfPkg/SmmAccess/SmmAccess2Dxe.c b/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
index e098f6f..3691a6c 100644
--- a/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
+++ b/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
@@ -145,6 +145,13 @@ SmmAccess2DxeEntryPoint (
 

   InitQ35TsegMbytes ();

   GetStates (&mAccess2.LockState, &mAccess2.OpenState);

+

+  //

+  // SmramAccessLock() depends on "mQ35SmramAtDefaultSmbase"; init the latter

+  // just before exposing the former via EFI_SMM_ACCESS2_PROTOCOL.Lock().

+  //

+  InitQ35SmramAtDefaultSmbase ();

+

   return gBS->InstallMultipleProtocolInterfaces (&ImageHandle,

                 &gEfiSmmAccess2ProtocolGuid, &mAccess2,

                 NULL);

diff --git a/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf b/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
index 7ced6b4..d86381d 100644
--- a/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
+++ b/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
@@ -49,6 +49,7 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire

 

 [Pcd]

+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase

   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes

 

 [Depex]

diff --git a/OvmfPkg/SmmAccess/SmmAccessPei.c b/OvmfPkg/SmmAccess/SmmAccessPei.c
index d678506..c8bbc17 100644
--- a/OvmfPkg/SmmAccess/SmmAccessPei.c
+++ b/OvmfPkg/SmmAccess/SmmAccessPei.c
@@ -373,6 +373,12 @@ SmmAccessPeiEntryPoint (
     sizeof SmramMap[DescIdxSmmS3ResumeState]);

 

   //

+  // SmramAccessLock() depends on "mQ35SmramAtDefaultSmbase"; init the latter

+  // just before exposing the former via PEI_SMM_ACCESS_PPI.Lock().

+  //

+  InitQ35SmramAtDefaultSmbase ();

+

+  //

   // We're done. The next step should succeed, but even if it fails, we can't

   // roll back the above BuildGuidHob() allocation, because PEI doesn't support

   // releasing memory.

diff --git a/OvmfPkg/SmmAccess/SmmAccessPei.inf b/OvmfPkg/SmmAccess/SmmAccessPei.inf
index d73a029..1698c4c 100644
--- a/OvmfPkg/SmmAccess/SmmAccessPei.inf
+++ b/OvmfPkg/SmmAccess/SmmAccessPei.inf
@@ -54,6 +54,7 @@
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire

 

 [Pcd]

+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase

   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes

 

 [Ppis]

diff --git a/OvmfPkg/SmmAccess/SmramInternal.c b/OvmfPkg/SmmAccess/SmramInternal.c
index 09657d0..0b07dc6 100644
--- a/OvmfPkg/SmmAccess/SmramInternal.c
+++ b/OvmfPkg/SmmAccess/SmramInternal.c
@@ -21,6 +21,12 @@
 //

 UINT16 mQ35TsegMbytes;

 

+//

+// The value of PcdQ35SmramAtDefaultSmbase is saved into this variable at

+// module startup.

+//

+STATIC BOOLEAN mQ35SmramAtDefaultSmbase;

+

 /**

   Save PcdQ35TsegMbytes into mQ35TsegMbytes.

 **/

@@ -33,6 +39,17 @@ InitQ35TsegMbytes (
 }

 

 /**

+  Save PcdQ35SmramAtDefaultSmbase into mQ35SmramAtDefaultSmbase.

+**/

+VOID

+InitQ35SmramAtDefaultSmbase (

+  VOID

+  )

+{

+  mQ35SmramAtDefaultSmbase = PcdGetBool (PcdQ35SmramAtDefaultSmbase);

+}

+

+/**

   Read the MCH_SMRAM and ESMRAMC registers, and update the LockState and

   OpenState fields in the PEI_SMM_ACCESS_PPI / EFI_SMM_ACCESS2_PROTOCOL object,

   from the D_LCK and T_EN bits.

@@ -125,6 +142,14 @@ SmramAccessLock (
   PciOr8 (DRAMC_REGISTER_Q35 (MCH_ESMRAMC), MCH_ESMRAMC_T_EN);

   PciOr8 (DRAMC_REGISTER_Q35 (MCH_SMRAM),   MCH_SMRAM_D_LCK);

 

+  //

+  // Close & lock the SMRAM at the default SMBASE, if it exists.

+  //

+  if (mQ35SmramAtDefaultSmbase) {

+    PciWrite8 (DRAMC_REGISTER_Q35 (MCH_DEFAULT_SMBASE_CTL),

+      MCH_DEFAULT_SMBASE_LCK);

+  }

+

   GetStates (LockState, OpenState);

   if (*OpenState || !*LockState) {

     return EFI_DEVICE_ERROR;

diff --git a/OvmfPkg/SmmAccess/SmramInternal.h b/OvmfPkg/SmmAccess/SmramInternal.h
index 74d962b..a4d8827 100644
--- a/OvmfPkg/SmmAccess/SmramInternal.h
+++ b/OvmfPkg/SmmAccess/SmramInternal.h
@@ -39,6 +39,14 @@ InitQ35TsegMbytes (
   );

 

 /**

+  Save PcdQ35SmramAtDefaultSmbase into mQ35SmramAtDefaultSmbase.

+**/

+VOID

+InitQ35SmramAtDefaultSmbase (

+  VOID

+  );

+

+/**

   Read the MCH_SMRAM and ESMRAMC registers, and update the LockState and

   OpenState fields in the PEI_SMM_ACCESS_PPI / EFI_SMM_ACCESS2_PROTOCOL object,

   from the D_LCK and T_EN bits.