BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275
Version 2 of the GHCB specification added the support to query the
hypervisor feature bitmap. The feature bitmap provide information
such as whether to use the AP create VmgExit or use the AP jump table
approach to create the APs. The MpInitLib will use the
PcdGhcbHypervisorFeatures to determine which method to use for creating
the AP.
Query the hypervisor feature and set the PCD accordingly.
Cc: James Bottomley <j...@linux.ibm.com>
Cc: Min Xu <min.m...@intel.com>
Cc: Jiewen Yao <jiewen....@intel.com>
Cc: Tom Lendacky <thomas.lenda...@amd.com>
Cc: Jordan Justen <jordan.l.jus...@intel.com>
Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Erdem Aktas <erdemak...@google.com>
Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
---
OvmfPkg/PlatformPei/PlatformPei.inf | 3 ++
OvmfPkg/PlatformPei/AmdSev.c | 55 +++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf
b/OvmfPkg/PlatformPei/PlatformPei.inf
index 041b3262ff3b..bd0ade9f33d7 100644
--- a/OvmfPkg/PlatformPei/PlatformPei.inf
+++ b/OvmfPkg/PlatformPei/PlatformPei.inf
@@ -62,6 +62,7 @@ [LibraryClasses]
MtrrLib
MemEncryptSevLib
PcdLib
+ VmgExitLib
[Pcd]
gUefiOvmfPkgTokenSpaceGuid.PcdOvmfPeiMemFvBase
@@ -107,6 +108,8 @@ [Pcd]
gUefiCpuPkgTokenSpaceGuid.PcdCpuApStackSize
gUefiCpuPkgTokenSpaceGuid.PcdSevEsIsEnabled
gUefiCpuPkgTokenSpaceGuid.PcdSevSnpIsEnabled
+ gUefiCpuPkgTokenSpaceGuid.PcdGhcbHypervisorFeatures
+
[FixedPcd]
gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index ec577ef3efcc..b488cd5aed9b 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -23,6 +23,12 @@
#include "Platform.h"
+STATIC
+UINT64
+GetHypervisorFeature (
+ VOID
+ );
+
/**
Initialize SEV-SNP support if running as an SEV-SNP guest.
@@ -36,6 +42,7 @@ AmdSevSnpInitialize (
RETURN_STATUS PcdStatus;
EFI_PEI_HOB_POINTERS Hob;
EFI_HOB_RESOURCE_DESCRIPTOR *ResourceHob;
+ UINT64 HvFeatures;
if (!MemEncryptSevSnpIsEnabled ()) {
return;
@@ -44,6 +51,15 @@ AmdSevSnpInitialize (
PcdStatus = PcdSetBoolS (PcdSevSnpIsEnabled, TRUE);
ASSERT_RETURN_ERROR (PcdStatus);
+ //
+ // Query the hypervisor feature using the VmgExit and set the value in the
+ // hypervisor features PCD.
+ //
+ HvFeatures = GetHypervisorFeature ();
+ PcdStatus = PcdSet64S (PcdGhcbHypervisorFeatures, HvFeatures);
+ ASSERT_RETURN_ERROR (PcdStatus);
+
+
//
// Iterate through the system RAM and validate it.
//
@@ -94,6 +110,45 @@ SevEsProtocolFailure (
CpuDeadLoop ();
}
+/**
+ Get the hypervisor features bitmap
+
+**/
+STATIC
+UINT64
+GetHypervisorFeature (
+ VOID
+ )
+{
+ RETURN_STATUS Status;
+ GHCB *Ghcb;
+ MSR_SEV_ES_GHCB_REGISTER Msr;
+ BOOLEAN InterruptState;
+ UINT64 Features;
+
+ Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
+ Ghcb = Msr.Ghcb;
+
+ //
+ // Initialize the GHCB
+ //
+ VmgInit (Ghcb, &InterruptState);
+
+ //
+ // Query the Hypervisor Features.
+ //
+ Status = VmgExit (Ghcb, SVM_EXIT_HYPERVISOR_FEATURES, 0, 0);
+ if ((Status != 0)) {
+ SevEsProtocolFailure (GHCB_TERMINATE_GHCB_GENERAL);
+ }
+
+ Features = Ghcb->SaveArea.SwExitInfo2;
+
+ VmgDone (Ghcb, InterruptState);
+
+ return Features;
+}
+
/**
This function can be used to register the GHCB GPA.
--
2.17.1
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