[edk2-devel] [PATCH v11 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
MEMORY_ACCEPTANCE_PROTOCOL to disable the accept behavior and 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 disable 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 e4e7b72e67..7d824cc282 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 = BZ3937_EFI_RESOURCE_MEMORY_UNACCEPTED;
+        continue;
+      }
 
       if (ResourceHob->ResourceType == EFI_RESOURCE_SYSTEM_MEMORY) {
         MemEncryptSevSnpPreValidateSystemRam (
-- 
2.39.1.456.gfc5497dd1b-goog



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