UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

Use the SEV-SNP AP Creation NAE event to create and launch APs under
SEV-SNP. This capability will be advertised in the SEV Hypervisor
Feature Support PCD (PcdSevEsHypervisorFeatures).

Cc: Michael Roth <michael.roth@amd.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.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: Ray Ni <ray.ni@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

1 files changed, 40 insertions, 19 deletions

diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index b73a6e9a0f..4a73787ee4 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -295,10 +295,12 @@ GetApLoopMode (
       ApLoopMode = ApInHltLoop;

     }

 

-    if (ConfidentialComputingGuestHas (CCAttrAmdSevEs)) {

+    if (ConfidentialComputingGuestHas (CCAttrAmdSevEs) &&

+        !ConfidentialComputingGuestHas (CCAttrAmdSevSnp))

+    {

       //

-      // For SEV-ES, force AP in Hlt-loop mode in order to use the GHCB

-      // protocol for starting APs

+      // For SEV-ES (SEV-SNP is also considered SEV-ES), force AP in Hlt-loop

+      // mode in order to use the GHCB protocol for starting APs

       //

       ApLoopMode = ApInHltLoop;

     }

@@ -763,7 +765,7 @@ ApWakeupFunction (
       // to allow the APs to issue an AP_RESET_HOLD before the BSP possibly

       // performs another INIT-SIPI-SIPI sequence.

       //

-      if (!CpuMpData->SevEsIsEnabled) {

+      if (!CpuMpData->UseSevEsAPMethod) {

         InterlockedDecrement ((UINT32 *)&CpuMpData->MpCpuExchangeInfo->NumApsExecuting);

       }

     }

@@ -777,7 +779,7 @@ ApWakeupFunction (
       //

       while (TRUE) {

         DisableInterrupts ();

-        if (CpuMpData->SevEsIsEnabled) {

+        if (CpuMpData->UseSevEsAPMethod) {

           SevEsPlaceApHlt (CpuMpData);

         } else {

           CpuSleep ();

@@ -1061,9 +1063,13 @@ AllocateResetVector (
                                     );

     //

     // The AP reset stack is only used by SEV-ES guests. Do not allocate it

-    // if SEV-ES is not enabled.

+    // if SEV-ES is not enabled. An SEV-SNP guest is also considered

+    // an SEV-ES guest, but uses a different method of AP startup, eliminating

+    // the need for the allocation.

     //

-    if (ConfidentialComputingGuestHas (CCAttrAmdSevEs)) {

+    if (ConfidentialComputingGuestHas (CCAttrAmdSevEs) &&

+        !ConfidentialComputingGuestHas (CCAttrAmdSevSnp))

+    {

       //

       // Stack location is based on ProcessorNumber, so use the total number

       // of processors for calculating the total stack area.

@@ -1114,7 +1120,7 @@ FreeResetVector (
   // perform the restore as this will overwrite memory which has data

   // needed by SEV-ES.

   //

-  if (!CpuMpData->SevEsIsEnabled) {

+  if (!CpuMpData->UseSevEsAPMethod) {

     RestoreWakeupBuffer (CpuMpData);

   }

 }

@@ -1193,7 +1199,7 @@ WakeUpAP (
 

     if (ResetVectorRequired) {

       //

-      // For SEV-ES, the initial AP boot address will be defined by

+      // For SEV-ES and SEV-SNP, the initial AP boot address will be defined by

       // PcdSevEsWorkAreaBase. The Segment/Rip must be the jump address

       // from the original INIT-SIPI-SIPI.

       //

@@ -1203,8 +1209,14 @@ WakeUpAP (
 

       //

       // Wakeup all APs

+      //   Must use the INIT-SIPI-SIPI method for initial configuration in

+      //   order to obtain the APIC ID.

       //

-      SendInitSipiSipiAllExcludingSelf ((UINT32)ExchangeInfo->BufferStart);

+      if (CpuMpData->SevSnpIsEnabled && (CpuMpData->InitFlag != ApInitConfig)) {

+        SevSnpCreateAP (CpuMpData, -1);

+      } else {

+        SendInitSipiSipiAllExcludingSelf ((UINT32)ExchangeInfo->BufferStart);

+      }

     }

 

     if (CpuMpData->InitFlag == ApInitConfig) {

@@ -1295,7 +1307,7 @@ WakeUpAP (
       CpuInfoInHob = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;

 

       //

-      // For SEV-ES, the initial AP boot address will be defined by

+      // For SEV-ES and SEV-SNP, the initial AP boot address will be defined by

       // PcdSevEsWorkAreaBase. The Segment/Rip must be the jump address

       // from the original INIT-SIPI-SIPI.

       //

@@ -1303,10 +1315,14 @@ WakeUpAP (
         SetSevEsJumpTable (ExchangeInfo->BufferStart);

       }

 

-      SendInitSipiSipi (

-        CpuInfoInHob[ProcessorNumber].ApicId,

-        (UINT32)ExchangeInfo->BufferStart

-        );

+      if (CpuMpData->SevSnpIsEnabled && (CpuMpData->InitFlag != ApInitConfig)) {

+        SevSnpCreateAP (CpuMpData, (INTN)ProcessorNumber);

+      } else {

+        SendInitSipiSipi (

+          CpuInfoInHob[ProcessorNumber].ApicId,

+          (UINT32)ExchangeInfo->BufferStart

+          );

+      }

     }

 

     //

@@ -1855,10 +1871,15 @@ MpInitLibInitialize (
   CpuMpData->CpuData          = (CPU_AP_DATA *)(CpuMpData + 1);

   CpuMpData->CpuInfoInHob     = (UINT64)(UINTN)(CpuMpData->CpuData + MaxLogicalProcessorNumber);

   InitializeSpinLock (&CpuMpData->MpLock);

-  CpuMpData->SevEsIsEnabled  = ConfidentialComputingGuestHas (CCAttrAmdSevEs);

-  CpuMpData->SevSnpIsEnabled = ConfidentialComputingGuestHas (CCAttrAmdSevSnp);

-  CpuMpData->SevEsAPBuffer   = (UINTN)-1;

-  CpuMpData->GhcbBase        = PcdGet64 (PcdGhcbBase);

+  CpuMpData->SevEsIsEnabled   = ConfidentialComputingGuestHas (CCAttrAmdSevEs);

+  CpuMpData->SevSnpIsEnabled  = ConfidentialComputingGuestHas (CCAttrAmdSevSnp);

+  CpuMpData->SevEsAPBuffer    = (UINTN)-1;

+  CpuMpData->GhcbBase         = PcdGet64 (PcdGhcbBase);

+  CpuMpData->UseSevEsAPMethod = CpuMpData->SevEsIsEnabled && !CpuMpData->SevSnpIsEnabled;

+

+  if (CpuMpData->SevSnpIsEnabled) {

+    ASSERT ((PcdGet64 (PcdGhcbHypervisorFeatures) & GHCB_HV_FEATURES_SNP_AP_CREATE) == GHCB_HV_FEATURES_SNP_AP_CREATE);

+  }

 

   //

   // Make sure no memory usage outside of the allocated buffer.