diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.c b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
index f7600c3c81..37d1a3ff55 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.c
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.c
@@ -20,6 +20,7 @@
 #include <Library/UefiBootServicesTableLib.h>
 #include <Guid/ConfidentialComputingSevSnpBlob.h>
 #include <Library/PcdLib.h>
+#include <Pi/PrePiDxeCis.h>
 #include <Protocol/MemoryAccept.h>
 
 STATIC CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION  mSnpBootDxeTable = {
@@ -34,6 +35,10 @@ STATIC CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION  mSnpBootDxeTable = {
 
 STATIC EFI_HANDLE  mAmdSevDxeHandle = NULL;
 
+STATIC BOOLEAN  mAcceptAllMemoryAtEBS = TRUE;
+
+STATIC EFI_EVENT  mAcceptAllMemoryEvent = NULL;
+
 #define IS_ALIGNED(x, y)  ((((x) & ((y) - 1)) == 0))
 
 STATIC
@@ -62,6 +67,82 @@ AmdSevMemoryAccept (
   return EFI_SUCCESS;
 }
 
+STATIC
+EFI_STATUS
+AcceptAllMemory (
+  VOID
+  )
+{
+  EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *AllDescMap;
+  UINTN                            NumEntries;
+  UINTN                            Index;
+  EFI_STATUS                       Status;
+
+  DEBUG ((DEBUG_INFO, "Accepting all memory\n"));
+
+  /*
+   * Get a copy of the memory space map to iterate over while
+   * changing the map.
+   */
+  Status = gDS->GetMemorySpaceMap (&NumEntries, &AllDescMap);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  for (Index = 0; Index < NumEntries; Index++) {
+    CONST EFI_GCD_MEMORY_SPACE_DESCRIPTOR  *Desc;
+
+    Desc = &AllDescMap[Index];
+    if (Desc->GcdMemoryType != EFI_GCD_MEMORY_TYPE_UNACCEPTED) {
+      continue;
+    }
+
+    Status = AmdSevMemoryAccept (
+               NULL,
+               Desc->BaseAddress,
+               Desc->Length
+               );
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+
+    Status = gDS->RemoveMemorySpace (Desc->BaseAddress, Desc->Length);
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+
+    Status = gDS->AddMemorySpace (
+                    EfiGcdMemoryTypeSystemMemory,
+                    Desc->BaseAddress,
+                    Desc->Length,
+                    EFI_MEMORY_CPU_CRYPTO | EFI_MEMORY_XP | EFI_MEMORY_RO | EFI_MEMORY_RP
+                    );
+    if (EFI_ERROR (Status)) {
+      break;
+    }
+  }
+
+  gBS->FreePool (AllDescMap);
+  return Status;
+}
+
+VOID
+EFIAPI
+ResolveUnacceptedMemory (
+  IN EFI_EVENT  Event,
+  IN VOID       *Context
+  )
+{
+  EFI_STATUS  Status;
+
+  if (!mAcceptAllMemoryAtEBS) {
+    return;
+  }
+
+  Status = AcceptAllMemory ();
+  ASSERT_EFI_ERROR (Status);
+}
+
 STATIC EDKII_MEMORY_ACCEPT_PROTOCOL  mMemoryAcceptProtocol = {
   AmdSevMemoryAccept
 };
@@ -195,6 +276,22 @@ AmdSevDxeEntryPoint (
                     );
     ASSERT_EFI_ERROR (Status);
 
+    // SEV-SNP support does not automatically imply unaccepted memory support,
+    // so make ExitBootServices accept all unaccepted memory if support is
+    // not communicated.
+    Status = gBS->CreateEventEx (
+                    EVT_NOTIFY_SIGNAL,
+                    TPL_CALLBACK,
+                    ResolveUnacceptedMemory,
+                    NULL,
+                    &gEfiEventBeforeExitBootServicesGuid,
+                    &mAcceptAllMemoryEvent
+                    );
+
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "AllowUnacceptedMemory event creation for EventBeforeExitBootServices failed.\n"));
+    }
+
     //
     // If its SEV-SNP active guest then install the CONFIDENTIAL_COMPUTING_SEV_SNP_BLOB.
     // It contains the location for both the Secrets and CPUID page.
diff --git a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
index cd1b686c53..5b443d45bc 100644
--- a/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
+++ b/OvmfPkg/AmdSevDxe/AmdSevDxe.inf
@@ -52,6 +52,7 @@
 
 [Guids]
   gConfidentialComputingSevSnpBlobGuid
+  gEfiEventBeforeExitBootServicesGuid
 
 [Pcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfHostBridgePciDevId