[PATCH v8 24/32] OvmfPkg/PlatformPei: set the Hypervisor Features PCD


Brijesh Singh
 

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: Michael Roth <michael.roth@amd.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
OvmfPkg/PlatformPei/PlatformPei.inf | 3 ++
OvmfPkg/PlatformPei/AmdSev.c | 56 +++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)

diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf b/OvmfPkg/PlatformPei/PlatformPei.inf
index 233b9494f64b..d048b692f155 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.PcdConfidentialComputingGuestAttr
+ gUefiCpuPkgTokenSpaceGuid.PcdGhcbHypervisorFeatures
+

[FixedPcd]
gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index 5e2c891309d4..b71a4a7304f7 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -24,6 +24,12 @@

#include "Platform.h"

+STATIC
+UINT64
+GetHypervisorFeature (
+ VOID
+ );
+
/**
Initialize SEV-SNP support if running as an SEV-SNP guest.

@@ -36,11 +42,22 @@ AmdSevSnpInitialize (
{
EFI_PEI_HOB_POINTERS Hob;
EFI_HOB_RESOURCE_DESCRIPTOR *ResourceHob;
+ UINT64 HvFeatures;
+ EFI_STATUS PcdStatus;

if (!MemEncryptSevSnpIsEnabled ()) {
return;
}

+ //
+ // 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.
//
@@ -91,6 +108,45 @@ SevEsProtocolFailure (
CpuDeadLoop ();
}

+/**
+ Get the hypervisor features bitmap
+
+**/
+STATIC
+UINT64
+GetHypervisorFeature (
+ VOID
+ )
+{
+ UINT64 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.
--
2.25.1