[edk2-devel] [PATCH 13/16] UefiCpuPkg/MpInitLib: Always use AP Create if PcdSevSnpApicIds is set

["Lendacky, Thomas via groups.io" <thomas.lendacky=amd.com@groups.io>]

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654

Currently, the first time an AP is started for an SEV-SNP guest, it relies
on the VMSA as set by the hypervisor. If the list of APIC IDs has been
retrieved, this is not necessary. Instead, use the SEV-SNP AP Create
protocol to start the AP for the first time and thereafter using the VMPL
at which the BSP is running.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf |  1 +
 UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf |  3 +-
 UefiCpuPkg/Library/MpInitLib/MpLib.h          | 13 ++++
 UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c    | 19 +++++
 UefiCpuPkg/Library/MpInitLib/MpLib.c          |  7 +-
 UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c     | 79 +++++++++++++++++++-
 6 files changed, 116 insertions(+), 6 deletions(-)

diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
index 55e46d4a1fad..1ec50481f0d4 100644
--- a/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
@@ -82,6 +82,7 @@ [Pcd]
   gUefiCpuPkgTokenSpaceGuid.PcdGhcbHypervisorFeatures                  ## CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase                       ## SOMETIMES_CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdFirstTimeWakeUpAPsBySipi                ## CONSUMES
+  gUefiCpuPkgTokenSpaceGuid.PcdSevSnpApicIds                           ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard                      ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase                           ## CONSUMES
   gEfiMdePkgTokenSpaceGuid.PcdConfidentialComputingGuestAttr           ## CONSUMES
diff --git a/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf b/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf
index bc3d716aa951..f0af07d3bdfb 100644
--- a/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf
+++ b/UefiCpuPkg/Library/MpInitLib/PeiMpInitLib.inf
@@ -66,7 +66,8 @@ [Pcd]
   gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate                   ## SOMETIMES_CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdSevEsWorkAreaBase                   ## SOMETIMES_CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdGhcbHypervisorFeatures              ## CONSUMES
-  gUefiCpuPkgTokenSpaceGuid.PcdFirstTimeWakeUpAPsBySipi             ## CONSUMES
+  gUefiCpuPkgTokenSpaceGuid.PcdFirstTimeWakeUpAPsBySipi            ## CONSUMES
+  gUefiCpuPkgTokenSpaceGuid.PcdSevSnpApicIds                       ## CONSUMES
   gEfiMdeModulePkgTokenSpaceGuid.PcdGhcbBase                       ## CONSUMES
   gEfiMdePkgTokenSpaceGuid.PcdConfidentialComputingGuestAttr       ## CONSUMES
 
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h b/UefiCpuPkg/Library/MpInitLib/MpLib.h
index 6e2137cb17cd..f1a5fa98d425 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
@@ -897,6 +897,19 @@ SevSnpCreateAP (
   IN INTN         ProcessorNumber
   );
 
+/**
+  Determine if the SEV-SNP AP Create protocol should be used.
+
+  @param[in]  CpuMpData  Pointer to CPU MP Data
+
+  @retval     TRUE       Use SEV-SNP AP Create protocol
+  @retval     FALSE      Do not use SEV-SNP AP Create protocol
+**/
+BOOLEAN
+SevSnpUseCreateAP (
+  IN  CPU_MP_DATA  *CpuMpData
+  );
+
 /**
   Get pointer to CPU MP Data structure from GUIDed HOB.
 
diff --git a/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c b/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
index a2b8a5b3f516..f9f24bee09de 100644
--- a/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
+++ b/UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c
@@ -48,3 +48,22 @@ SevSnpCreateAP (
   //
   ASSERT (FALSE);
 }
+
+/**
+  Determine if the SEV-SNP AP Create protocol should be used.
+
+  @param[in]  CpuMpData  Pointer to CPU MP Data
+
+  @retval     TRUE       Use SEV-SNP AP Create protocol
+  @retval     FALSE      Do not use SEV-SNP AP Create protocol
+**/
+BOOLEAN
+SevSnpUseCreateAP (
+  IN  CPU_MP_DATA  *CpuMpData
+  )
+{
+  //
+  // SEV-SNP is not supported on 32-bit build.
+  //
+  return FALSE;
+}
diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
index cdfb570e61a0..5e017bcf9018 100644
--- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
+++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
@@ -1302,9 +1302,10 @@ WakeUpAP (
       //
       // Wakeup all APs
       //   Must use the INIT-SIPI-SIPI method for initial configuration in
-      //   order to obtain the APIC ID.
+      //   order to obtain the APIC ID if not an SEV-SNP guest and the
+      //   list of APIC IDs is not available.
       //
-      if (CpuMpData->SevSnpIsEnabled && (CpuMpData->InitFlag != ApInitConfig)) {
+      if (SevSnpUseCreateAP (CpuMpData)) {
         SevSnpCreateAP (CpuMpData, -1);
       } else {
         if ((CpuMpData->InitFlag == ApInitConfig) && FixedPcdGetBool (PcdFirstTimeWakeUpAPsBySipi)) {
@@ -1414,7 +1415,7 @@ WakeUpAP (
         SetSevEsJumpTable (ExchangeInfo->BufferStart);
       }
 
-      if (CpuMpData->SevSnpIsEnabled && (CpuMpData->InitFlag != ApInitConfig)) {
+      if (SevSnpUseCreateAP (CpuMpData)) {
         SevSnpCreateAP (CpuMpData, (INTN)ProcessorNumber);
       } else {
         SendInitSipiSipi (
diff --git a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
index db9a37fbbd19..6186a8d71521 100644
--- a/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
+++ b/UefiCpuPkg/Library/MpInitLib/X64/AmdSev.c
@@ -263,17 +263,63 @@ SevSnpCreateAP (
   CPU_INFO_IN_HOB  *CpuInfoInHob;
   CPU_AP_DATA      *CpuData;
   UINTN            Index;
+  UINTN            MaxIndex;
   UINT32           ApicId;
+  GHCB_APIC_IDS    *GhcbApicIds;
 
   ASSERT (CpuMpData->MpCpuExchangeInfo->BufferStart < 0x100000);
 
   CpuInfoInHob = (CPU_INFO_IN_HOB *)(UINTN)CpuMpData->CpuInfoInHob;
 
   if (ProcessorNumber < 0) {
-    for (Index = 0; Index < CpuMpData->CpuCount; Index++) {
+    GhcbApicIds = (GHCB_APIC_IDS *)(UINTN)PcdGet64 (PcdSevSnpApicIds);
+
+    if (CpuMpData->InitFlag == ApInitConfig) {
+      //
+      // APs have not been started, so CpuCount is not "known" yet.
+      // Use the retrieved APIC IDs to start the APs and fill out the
+      // MpLib CPU information properly.
+      //
+      ASSERT (GhcbApicIds != NULL);
+      if (GhcbApicIds == NULL) {
+        return;
+      }
+
+      MaxIndex = MIN (GhcbApicIds->NumEntries, PcdGet32 (PcdCpuMaxLogicalProcessorNumber));
+    } else {
+      //
+      // APs have been previously started.
+      //
+      MaxIndex = CpuMpData->CpuCount;
+    }
+
+    for (Index = 0; Index < MaxIndex; Index++) {
       if (Index != CpuMpData->BspNumber) {
         CpuData = &CpuMpData->CpuData[Index];
-        ApicId  = CpuInfoInHob[Index].ApicId,
+
+        if (CpuMpData->InitFlag == ApInitConfig) {
+          //
+          // CodeQL doesn't understand that a check for NULL was already done
+          // above, so check again.
+          //
+          if (GhcbApicIds == NULL) {
+            return;
+          }
+
+          ApicId = GhcbApicIds->ApicIds[Index];
+
+          //
+          // For the first boot, use the BSP register information.
+          //
+          CopyMem (
+            &CpuData->VolatileRegisters,
+            &CpuMpData->CpuData[0].VolatileRegisters,
+            sizeof (CpuData->VolatileRegisters)
+            );
+        } else {
+          ApicId = CpuInfoInHob[Index].ApicId;
+        }
+
         SevSnpCreateSaveArea (CpuMpData, CpuData, ApicId);
       }
     }
@@ -284,3 +330,32 @@ SevSnpCreateAP (
     SevSnpCreateSaveArea (CpuMpData, CpuData, ApicId);
   }
 }
+
+/**
+  Determine if the SEV-SNP AP Create protocol should be used.
+
+  @param[in]  CpuMpData  Pointer to CPU MP Data
+
+  @retval     TRUE       Use SEV-SNP AP Create protocol
+  @retval     FALSE      Do not use SEV-SNP AP Create protocol
+**/
+BOOLEAN
+SevSnpUseCreateAP (
+  IN  CPU_MP_DATA  *CpuMpData
+  )
+{
+  //
+  // The AP Create protocol is used for an SEV-SNP guest if
+  //   - The initial configuration has been performed already or
+  //   - PcdSevSnpApicIds is non-zero.
+  //
+  if (!CpuMpData->SevSnpIsEnabled) {
+    return FALSE;
+  }
+
+  if ((CpuMpData->InitFlag == ApInitConfig) && (PcdGet64 (PcdSevSnpApicIds) == 0)) {
+    return FALSE;
+  }
+
+  return TRUE;
+}
-- 
2.42.0



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#114639): https://edk2.groups.io/g/devel/message/114639
Mute This Topic: https://groups.io/mt/103986469/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-