BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198
Currently, the OVMF code relies on the hypervisor to enable the cache
support on the processor in order to improve the boot speed. However,
with SEV-ES, the hypervisor is not allowed to change the CR0 register
to enable caching.
Update the OVMF Sec support to enable caching in order to improve the
boot speed when running as an SEV-ES guest.
Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
Signed-off-by: Tom Lendacky <thomas.lenda...@amd.com>
---
OvmfPkg/Sec/SecMain.c | 45 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)
diff --git a/OvmfPkg/Sec/SecMain.c b/OvmfPkg/Sec/SecMain.c
index db319030ee58..53c850134897 100644
--- a/OvmfPkg/Sec/SecMain.c
+++ b/OvmfPkg/Sec/SecMain.c
@@ -25,6 +25,9 @@
#include <Library/ExtractGuidedSectionLib.h>
#include <Library/LocalApicLib.h>
#include <Library/CpuExceptionHandlerLib.h>
+#include <Register/Cpuid.h>
+#include <Register/Amd/Cpuid.h>
+#include <Register/Amd/Fam17Msr.h>
#include <Ppi/TemporaryRamSupport.h>
@@ -713,6 +716,39 @@ FindAndReportEntryPoints (
return;
}
+STATIC
+BOOLEAN
+SevEsIsEnabled (
+ VOID
+ )
+{
+ UINT32 RegEax;
+ CPUID_MEMORY_ENCRYPTION_INFO_EAX Eax;
+ MSR_SEV_STATUS_REGISTER Msr;
+
+ //
+ // Check if the memory encryption leaf exist
+ //
+ AsmCpuid (CPUID_EXTENDED_FUNCTION, &RegEax, NULL, NULL, NULL);
+ if (RegEax >= CPUID_MEMORY_ENCRYPTION_INFO) {
+ //
+ // CPUID Fn8000_001F[EAX] Bit 1 (Sev supported)
+ //
+ AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, &Eax.Uint32, NULL, NULL, NULL);
+ if (Eax.Bits.SevBit && Eax.Bits.SevEsBit) {
+ //
+ // Check MSR_0xC0010131 Bit 1 (Sev-Es Enabled)
+ //
+ Msr.Uint32 = AsmReadMsr32 (MSR_SEV_STATUS);
+ if (Msr.Bits.SevEsBit) {
+ return TRUE;
+ }
+ }
+ }
+
+ return FALSE;
+}
+
VOID
EFIAPI
SecCoreStartupWithStack (
@@ -755,6 +791,15 @@ SecCoreStartupWithStack (
ProcessLibraryConstructorList (NULL, NULL);
+ //
+ // Under SEV-ES, the hypervisor can't modify CR0 and so can't enable
+ // caching in order to speed up the boot. Enable caching early for
+ // an SEV-ES guest.
+ //
+ if (SevEsIsEnabled()) {
+ AsmEnableCache ();
+ }
+
DEBUG ((EFI_D_INFO,
"SecCoreStartupWithStack(0x%x, 0x%x)\n",
(UINT32)(UINTN)BootFv,
--
2.17.1
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