[edk2-devel] [PATCH v3 4/4] OvmfPkg/PlatformPei: SEV-SNP make >=4GB unaccepted

[Dionna Glaze via groups.io]

Instead of eagerly accepting all memory in PEI, only accept memory under
the 4GB address. This allows a loaded image to use the
ENABLE_UNACCEPTED_MEMORY_PROTOCOL to indicate that it can interpret the
memory type accordingly.

This classification is safe since ExitBootServices will accept and
reclassify the memory as conventional if the enable protocol is not
used.

Cc: Ard Biescheuvel <ardb at kernel.org>
Cc: "Min M. Xu" <min.m.xu at intel.com>
Cc: Gerd Hoffmann <kraxel at redhat.com>
Cc: James Bottomley <jejb at linux.ibm.com>
Cc: Tom Lendacky <Thomas.Lendacky at amd.com>
Cc: Jiewen Yao <jiewen.yao at intel.com>
Cc: Erdem Aktas <erdemaktas at google.com>

Signed-off-by: Dionna Glaze <dionnaglaze at google.com>
---
 OvmfPkg/PlatformPei/AmdSev.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index 385562b44c..2a52d6f491 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -16,6 +16,7 @@
 #include <Library/MemEncryptSevLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/PcdLib.h>
+#include <Pi/PrePiHob.h>
 #include <PiPei.h>
 #include <Register/Amd/Msr.h>
 #include <Register/Intel/SmramSaveStateMap.h>
@@ -63,6 +64,10 @@ AmdSevSnpInitialize (
   for (Hob.Raw = GetHobList (); !END_OF_HOB_LIST (Hob); Hob.Raw = GET_NEXT_HOB (Hob)) {
     if ((Hob.Raw != NULL) && (GET_HOB_TYPE (Hob) == EFI_HOB_TYPE_RESOURCE_DESCRIPTOR)) {
       ResourceHob = Hob.ResourceDescriptor;
+      if (ResourceHob->PhysicalStart >= SIZE_4GB) {
+        ResourceHob->ResourceType = EFI_RESOURCE_MEMORY_UNACCEPTED;
+        continue;
+      }
 
       if (ResourceHob->ResourceType == EFI_RESOURCE_SYSTEM_MEMORY) {
         MemEncryptSevSnpPreValidateSystemRam (
-- 
2.37.3.998.g577e59143f-goog



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