[PATCH v4 10/35] OvmfPkg/XenPlatformPei: Detect OVMF_INFO from hvmloader

["Anthony PERARD" <anthony.perard@citrix.com>]

EFI_XEN_OVMF_INFO is only useful to retrieve the E820 table. The
mXenHvmloaderInfo isn't used yet, but will be use in a further patch to
retrieve the E820 table.

Also remove the unused pointer from the XenInfo HOB as that information
is only useful in the XenPlatformPei.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
---

Notes:
    v3:
    - fix coding style
    - fix commit message

 OvmfPkg/Include/Guid/XenInfo.h |  4 ----
 OvmfPkg/PlatformPei/Xen.c      |  3 ---
 OvmfPkg/XenPlatformPei/Xen.c   | 25 +++++++++++++++++++++++--
 3 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/OvmfPkg/Include/Guid/XenInfo.h b/OvmfPkg/Include/Guid/XenInfo.h
index 25d76a7828..b052d618fd 100644
--- a/OvmfPkg/Include/Guid/XenInfo.h
+++ b/OvmfPkg/Include/Guid/XenInfo.h
@@ -18,10 +18,6 @@ typedef struct {
   ///
   VOID *HyperPages;
   ///
-  /// Location of the hvm_info page.
-  ///
-  VOID *HvmInfo;
-  ///
   /// Hypervisor major version.
   ///
   UINT16 VersionMajor;
diff --git a/OvmfPkg/PlatformPei/Xen.c b/OvmfPkg/PlatformPei/Xen.c
index 89dc4143b2..3e15b32a73 100644
--- a/OvmfPkg/PlatformPei/Xen.c
+++ b/OvmfPkg/PlatformPei/Xen.c
@@ -98,9 +98,6 @@ XenConnect (
   mXenInfo.VersionMajor = (UINT16)(XenVersion >> 16);
   mXenInfo.VersionMinor = (UINT16)(XenVersion & 0xFFFF);
 
-  /* TBD: Locate hvm_info and reserve it away. */
-  mXenInfo.HvmInfo = NULL;
-
   BuildGuidDataHob (
     &gEfiXenInfoGuid,
     &mXenInfo,
diff --git a/OvmfPkg/XenPlatformPei/Xen.c b/OvmfPkg/XenPlatformPei/Xen.c
index f4d0d1c73b..9962fe9fc7 100644
--- a/OvmfPkg/XenPlatformPei/Xen.c
+++ b/OvmfPkg/XenPlatformPei/Xen.c
@@ -33,6 +33,12 @@ STATIC UINT32 mXenLeaf = 0;
 
 EFI_XEN_INFO mXenInfo;
 
+//
+// Location of the firmware info struct setup by hvmloader.
+// Only the E820 table is used by OVMF.
+//
+EFI_XEN_OVMF_INFO *mXenHvmloaderInfo;
+
 /**
   Returns E820 map provided by Xen
 
@@ -78,6 +84,8 @@ XenConnect (
   UINT32 TransferReg;
   UINT32 TransferPages;
   UINT32 XenVersion;
+  EFI_XEN_OVMF_INFO *Info;
+  CHAR8 Sig[sizeof (Info->Signature) + 1];
 
   AsmCpuid (XenLeaf + 2, &TransferPages, &TransferReg, NULL, NULL);
   mXenInfo.HyperPages = AllocatePages (TransferPages);
@@ -97,8 +105,21 @@ XenConnect (
   mXenInfo.VersionMajor = (UINT16)(XenVersion >> 16);
   mXenInfo.VersionMinor = (UINT16)(XenVersion & 0xFFFF);
 
-  /* TBD: Locate hvm_info and reserve it away. */
-  mXenInfo.HvmInfo = NULL;
+  //
+  // Check if there are information left by hvmloader
+  //
+
+  Info = (EFI_XEN_OVMF_INFO *)(UINTN) OVMF_INFO_PHYSICAL_ADDRESS;
+  //
+  // Copy the signature, and make it null-terminated.
+  //
+  AsciiStrnCpyS (Sig, sizeof (Sig), (CHAR8 *) &Info->Signature,
+    sizeof (Info->Signature));
+  if (AsciiStrCmp (Sig, "XenHVMOVMF") == 0) {
+    mXenHvmloaderInfo = Info;
+  } else {
+    mXenHvmloaderInfo = NULL;
+  }
 
   BuildGuidDataHob (
     &gEfiXenInfoGuid,
-- 
Anthony PERARD