OvmfPkg: Retrieve SMBIOS from Cloud Hypervisor

Add a fallback on the SMBIOS code to find the SMBIOS table for Cloud
Hypervisor if it couldn't be found for Qemu through fw_cfg.

Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

OvmfPkg/SmbiosPlatformDxe/CloudHv.c

@@ -0,0 +1,33 @@
+/** @file
+  Find Cloud Hypervisor SMBIOS data.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <IndustryStandard/CloudHv.h> // CLOUDHV_SMBIOS_ADDRESS
+#include <IndustryStandard/SmBios.h>  // SMBIOS_TABLE_3_0_ENTRY_POINT
+
+/**
+  Locates and extracts Cloud Hypervisor SMBIOS data
+
+  @return                 Address of extracted Cloud Hypervisor SMBIOS data
+
+**/
+UINT8 *
+GetCloudHvSmbiosTables (
+  VOID
+  )
+{
+  SMBIOS_TABLE_3_0_ENTRY_POINT  *CloudHvTables = (VOID *)CLOUDHV_SMBIOS_ADDRESS;
+
+  if ((CloudHvTables->AnchorString[0] == '_') &&
+      (CloudHvTables->AnchorString[1] == 'S') &&
+      (CloudHvTables->AnchorString[2] == 'M') &&
+      (CloudHvTables->AnchorString[3] == '3') &&
+      (CloudHvTables->AnchorString[4] == '_'))
+  {
+    return (UINT8 *)(UINTN)CloudHvTables->TableAddress;
+  }
+
+  return NULL;
+}