[edk2-devel] [PATCH 1/1] OvmfPkg/Sec: Setup MTRR early in the boot process.

["Gerd Hoffmann" <kraxel@redhat.com>]

Specifically before running lzma uncompress of the main firmware volume.
This is needed to make sure caching is enabled, otherwise the uncompress
can be extremely slow.

Adapt the ASSERTs in PlatformInitLib to the changes.

Background:  In some virtual machine configurations with assigned
devices kvm uses EPT memory types to apply guest MTRR settings.
In case MTRRs are disabled kvm will use the uncachable memory type
for all mappings.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 OvmfPkg/Library/PlatformInitLib/MemDetect.c |  8 ++++--
 OvmfPkg/Sec/SecMain.c                       | 32 +++++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
index f042517bb64a..cb2ae0f3d79d 100644
--- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
+++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
@@ -1082,11 +1082,13 @@ PlatformQemuInitializeRam (
     MtrrGetAllMtrrs (&MtrrSettings);
 
     //
-    // MTRRs disabled, fixed MTRRs disabled, default type is uncached
+    // Fixed MTRRs disabled, default type is uncached or write back (see SecMtrrSetup())
     //
-    ASSERT ((MtrrSettings.MtrrDefType & BIT11) == 0);
     ASSERT ((MtrrSettings.MtrrDefType & BIT10) == 0);
-    ASSERT ((MtrrSettings.MtrrDefType & 0xFF) == 0);
+    ASSERT (
+      (MtrrSettings.MtrrDefType & 0xFF) == 0x0 ||
+      (MtrrSettings.MtrrDefType & 0xFF) == 0x6
+      );
 
     //
     // flip default type to writeback
diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index 31da5d0ace51..a672751b046a 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -30,6 +30,8 @@
 #include <Ppi/MpInitLibDep.h>
 #include <Library/TdxHelperLib.h>
 #include <Library/CcProbeLib.h>
+#include <Register/Intel/ArchitecturalMsr.h>
+#include <Register/Intel/Cpuid.h>
 #include "AmdSev.h"
 
 #define SEC_IDT_ENTRY_COUNT  34
@@ -744,6 +746,31 @@ FindAndReportEntryPoints (
   return;
 }
 
+//
+// Enable MTRR early, set default type to write back.
+// Needed to make sure caching is enabled,
+// without this lzma decompress can be very slow.
+//
+STATIC
+VOID
+SecMtrrSetup (
+  VOID
+  )
+{
+  CPUID_VERSION_INFO_EDX           Edx;
+  MSR_IA32_MTRR_DEF_TYPE_REGISTER  DefType;
+
+  AsmCpuid (CPUID_VERSION_INFO, NULL, NULL, NULL, &Edx.Uint32);
+  if (!Edx.Bits.MTRR) {
+    return;
+  }
+
+  DefType.Uint64    = 0;
+  DefType.Bits.Type = 6; /* write back */
+  DefType.Bits.E    = 1; /* enable */
+  AsmWriteMsr64 (MSR_IA32_MTRR_DEF_TYPE, DefType.Uint64);
+}
+
 VOID
 EFIAPI
 SecCoreStartupWithStack (
@@ -942,6 +969,11 @@ SecCoreStartupWithStack (
   InitializeApicTimer (0, MAX_UINT32, TRUE, 5);
   DisableApicTimerInterrupt ();
 
+  //
+  // Initialize MTRR
+  //
+  SecMtrrSetup ();
+
   //
   // Initialize Debug Agent to support source level debug in SEC/PEI phases before memory ready.
   //
-- 
2.43.0



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