From: Min M Xu <min.m.xu@intel.com>

ReserveEmuVariableNvStore is updated with below 2 functions defined in
PlatformInitLib:
 - PlatformReserveEmuVariableNvStore
 - PlatformInitEmuVariableNvStore

PlatformInitEmuVariableNvStore works when secure boot feature is enabled.
This is because secure boot needs the EFI variables (PK/KEK/DB/DBX, etc)
and EmuVariableNvStore is cleared when OVMF is launched with -bios
parameter.

Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com> [jejb]
Cc: Jiewen Yao <jiewen.yao@intel.com> [jyao1]
Cc: Tom Lendacky <thomas.lendacky@amd.com> [tlendacky]
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
---
 OvmfPkg/PlatformPei/Platform.c | 25 +++++++------------------
 1 file changed, 7 insertions(+), 18 deletions(-)

diff --git a/OvmfPkg/PlatformPei/Platform.c b/OvmfPkg/PlatformPei/Platform.c
index 009db67ee60a..b1f8140d6041 100644
--- a/OvmfPkg/PlatformPei/Platform.c
+++ b/OvmfPkg/PlatformPei/Platform.c
@@ -220,24 +220,13 @@ ReserveEmuVariableNvStore (
   EFI_PHYSICAL_ADDRESS  VariableStore;
   RETURN_STATUS         PcdStatus;
 
-  //
-  // Allocate storage for NV variables early on so it will be
-  // at a consistent address.  Since VM memory is preserved
-  // across reboots, this allows the NV variable storage to survive
-  // a VM reboot.
-  //
-  VariableStore =
-    (EFI_PHYSICAL_ADDRESS)(UINTN)
-    AllocateRuntimePages (
-      EFI_SIZE_TO_PAGES (2 * PcdGet32 (PcdFlashNvStorageFtwSpareSize))
-      );
-  DEBUG ((
-    DEBUG_INFO,
-    "Reserved variable store memory: 0x%lX; size: %dkb\n",
-    VariableStore,
-    (2 * PcdGet32 (PcdFlashNvStorageFtwSpareSize)) / 1024
-    ));
-  PcdStatus = PcdSet64S (PcdEmuVariableNvStoreReserved, VariableStore);
+  VariableStore = (EFI_PHYSICAL_ADDRESS)(UINTN)PlatformReserveEmuVariableNvStore ();
+  PcdStatus     = PcdSet64S (PcdEmuVariableNvStoreReserved, VariableStore);
+
+ #ifdef SECURE_BOOT_FEATURE_ENABLED
+  PlatformInitEmuVariableNvStore ((VOID *)(UINTN)VariableStore);
+ #endif
+
   ASSERT_RETURN_ERROR (PcdStatus);
 }
 
-- 
2.29.2.windows.2



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  Hi,

> + #ifdef SECURE_BOOT_FEATURE_ENABLED
> +  PlatformInitEmuVariableNvStore ((VOID *)(UINTN)VariableStore);
> + #endif

OvmfPkg/Library/NvVarsFileLib/ allows loading variables into emulated
varstore from a on-disk NvVars file.  We can't allow that when secure
boot is active.  I think we need a simliar check there.  Shortcutting
the ConnectNvVarsToFileSystem() function with a

#ifdef SECURE_BOOT_FEATURE_ENABLED
	return EFI_NOT_SUPPORTED;
#endif

should do the trick I think.

thanks,
  Gerd



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On June 27, 2022 5:14 PM, Gerd Hoffmann wrote:
> > + #ifdef SECURE_BOOT_FEATURE_ENABLED
> > +  PlatformInitEmuVariableNvStore ((VOID *)(UINTN)VariableStore);
> > + #endif
> 
> OvmfPkg/Library/NvVarsFileLib/ allows loading variables into emulated
> varstore from a on-disk NvVars file.  We can't allow that when secure boot is
> active.  I think we need a simliar check there.  Shortcutting the
> ConnectNvVarsToFileSystem() function with a
> 
> #ifdef SECURE_BOOT_FEATURE_ENABLED
> 	return EFI_NOT_SUPPORTED;
> #endif
> 
> should do the trick I think.
> 
A good suggestion. It will be updated in the next version.

Thanks
Min


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