OvmfPkg/AcpiPlatformDxe: replay QEMU_LOADER_WRITE_POINTER commands at S3

Ultimately, each QEMU_LOADER_WRITE_POINTER command creates a guest memory
reference in some QEMU device. When the virtual machine is reset, the
device willfully forgets the guest address, since the guest memory is
wholly invalidated during platform reset.

... Unless the reset is part of S3 resume. Then the guest memory is
preserved intact, and the firmware must reprogram those devices with the
original guest memory allocation addresses.

This patch accumulates the fw_cfg select, skip and write operations of
ProcessCmdWritePointer() in a validated / condensed form, and turns them
into an ACPI S3 Boot Script fragment at the very end of
InstallQemuFwCfgTables().

Cc: Jordan Justen <jordan.l.justen@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=359
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

1 files changed, 65 insertions, 5 deletions

diff --git a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
index de827c2df2..eadd690bef 100644
--- a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
+++ b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c
@@ -360,6 +360,11 @@ ProcessCmdAddChecksum (
   @param[in] Tracker        The ORDERED_COLLECTION tracking the BLOB user

                             structures created thus far.

 

+  @param[in,out] S3Context  The S3_CONTEXT object capturing the fw_cfg actions

+                            of successfully processed QEMU_LOADER_WRITE_POINTER

+                            commands, to be replayed at S3 resume. S3Context

+                            may be NULL if S3 is disabled.

+

   @retval EFI_PROTOCOL_ERROR  Malformed fw_cfg file name(s) have been found in

                               WritePointer. Or, the WritePointer command

                               references a file unknown to Tracker or the

@@ -369,13 +374,21 @@ ProcessCmdAddChecksum (
                               does not fit in the given pointer size.

 

   @retval EFI_SUCCESS         The pointer object inside the writeable fw_cfg

-                              file has been written.

+                              file has been written. If S3Context is not NULL,

+                              then WritePointer has been condensed into

+                              S3Context.

+

+  @return                     Error codes propagated from

+                              SaveCondensedWritePointerToS3Context(). The

+                              pointer object inside the writeable fw_cfg file

+                              has not been written.

 **/

 STATIC

 EFI_STATUS

 ProcessCmdWritePointer (

   IN     CONST QEMU_LOADER_WRITE_POINTER *WritePointer,

-  IN     CONST ORDERED_COLLECTION        *Tracker

+  IN     CONST ORDERED_COLLECTION        *Tracker,

+  IN OUT       S3_CONTEXT                *S3Context OPTIONAL

   )

 {

   RETURN_STATUS            Status;

@@ -432,6 +445,25 @@ ProcessCmdWritePointer (
     return EFI_PROTOCOL_ERROR;

   }

 

+  //

+  // If S3 is enabled, we have to capture the below fw_cfg actions in condensed

+  // form, to be replayed during S3 resume.

+  //

+  if (S3Context != NULL) {

+    EFI_STATUS SaveStatus;

+

+    SaveStatus = SaveCondensedWritePointerToS3Context (

+                   S3Context,

+                   (UINT16)PointerItem,

+                   WritePointer->PointerSize,

+                   WritePointer->PointerOffset,

+                   PointerValue

+                   );

+    if (EFI_ERROR (SaveStatus)) {

+      return SaveStatus;

+    }

+  }

+

   QemuFwCfgSelectItem (PointerItem);

   QemuFwCfgSkipBytes (WritePointer->PointerOffset);

   QemuFwCfgWriteBytes (WritePointer->PointerSize, &PointerValue);

@@ -701,6 +733,7 @@ InstallQemuFwCfgTables (
   CONST QEMU_LOADER_ENTRY  *WritePointerSubsetEnd;

   ORIGINAL_ATTRIBUTES      *OriginalPciAttributes;

   UINTN                    OriginalPciAttributesCount;

+  S3_CONTEXT               *S3Context;

   ORDERED_COLLECTION       *Tracker;

   UINTN                    *InstalledKey;

   INT32                    Installed;

@@ -726,10 +759,22 @@ InstallQemuFwCfgTables (
   RestorePciDecoding (OriginalPciAttributes, OriginalPciAttributesCount);

   LoaderEnd = LoaderStart + FwCfgSize / sizeof *LoaderEntry;

 

+  S3Context = NULL;

+  if (QemuFwCfgS3Enabled ()) {

+    //

+    // Size the allocation pessimistically, assuming that all commands in the

+    // script are QEMU_LOADER_WRITE_POINTER commands.

+    //

+    Status = AllocateS3Context (&S3Context, LoaderEnd - LoaderStart);

+    if (EFI_ERROR (Status)) {

+      goto FreeLoader;

+    }

+  }

+

   Tracker = OrderedCollectionInit (BlobCompare, BlobKeyCompare);

   if (Tracker == NULL) {

     Status = EFI_OUT_OF_RESOURCES;

-    goto FreeLoader;

+    goto FreeS3Context;

   }

 

   //

@@ -758,7 +803,7 @@ InstallQemuFwCfgTables (
 

     case QemuLoaderCmdWritePointer:

         Status = ProcessCmdWritePointer (&LoaderEntry->Command.WritePointer,

-                   Tracker);

+                   Tracker, S3Context);

         if (!EFI_ERROR (Status)) {

           WritePointerSubsetEnd = LoaderEntry + 1;

         }

@@ -790,11 +835,21 @@ InstallQemuFwCfgTables (
       Status = Process2ndPassCmdAddPointer (&LoaderEntry->Command.AddPointer,

                  Tracker, AcpiProtocol, InstalledKey, &Installed);

       if (EFI_ERROR (Status)) {

-        break;

+        goto UninstallAcpiTables;

       }

     }

   }

 

+  //

+  // Translating the condensed QEMU_LOADER_WRITE_POINTER commands to ACPI S3

+  // Boot Script opcodes has to be the last operation in this function, because

+  // if it succeeds, it cannot be undone.

+  //

+  if (S3Context != NULL) {

+    Status = TransferS3ContextToBootScript (S3Context);

+  }

+

+UninstallAcpiTables:

   if (EFI_ERROR (Status)) {

     //

     // roll back partial installation

@@ -847,6 +902,11 @@ RollbackWritePointersAndFreeTracker:
   }

   OrderedCollectionUninit (Tracker);

 

+FreeS3Context:

+  if (S3Context != NULL) {

+    ReleaseS3Context (S3Context);

+  }

+

 FreeLoader:

   FreePool (LoaderStart);