From 18fdffe825683df40d7a4a9eba11b8630bcef050 Mon Sep 17 00:00:00 2001
From: Tom Lendacky <thomas.lendacky@amd.com>
Date: Fri, 8 Mar 2024 07:32:32 -0800
Subject: [PATCH] OvmfPkg/BaseMemEncryptSevLib: Maximize Page State Change
 efficiency

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654

Similar to the Page State Change optimization added previously, also take
into account the possiblity of using the SVSM for PVALIDATE instructions.
Conditionally adjust the maximum number of entries based on how many
entries the SVSM calling area can support.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Michael Roth <michael.roth@amd.com>
Cc: Min Xu <min.m.xu@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 .../BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c  | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
index c8c0c4ef0e..e073f3937c 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/SnpPageStateChangeInternal.c
@@ -18,6 +18,7 @@
 
 #include <Register/Amd/Ghcb.h>
 #include <Register/Amd/Msr.h>
+#include <Register/Amd/Svsm.h>
 
 #include "SnpPageStateChange.h"
 
@@ -78,6 +79,7 @@ BuildPageStateBuffer (
   UINTN                 Index;
   UINTN                 IndexMax;
   UINTN                 PscIndexMax;
+  UINTN                 SvsmIndexMax;
 
   // Clear the page state structure
   SetMem (Info, InfoSize, 0);
@@ -96,6 +98,11 @@ BuildPageStateBuffer (
     IndexMax = MIN (IndexMax, PscIndexMax);
   }
 
+  SvsmIndexMax = (IndexMax / SVSM_PVALIDATE_MAX_ENTRY) * SVSM_PVALIDATE_MAX_ENTRY;
+  if (SvsmIndexMax > 0) {
+    IndexMax = MIN (IndexMax, SvsmIndexMax);
+  }
+
   //
   // Populate the page state entry structure
   //