[PATCH v4 19/35] OvmfPkg/XenPlatformPei: Setup HyperPages earlier

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

We are going to need to make an hypercall in order to retreive the E820
table from the hypervisor before been able to setup the memory.

Calling XenConnect earlier will allow to setup the XenHypercallLib
earlier to allow to make hypercalls.

While here, add some comments in XenConnect().

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>
---
 OvmfPkg/XenPlatformPei/Platform.h |  5 +++++
 OvmfPkg/XenPlatformPei/Platform.c |  2 ++
 OvmfPkg/XenPlatformPei/Xen.c      | 23 ++++++++++++-----------
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/OvmfPkg/XenPlatformPei/Platform.h b/OvmfPkg/XenPlatformPei/Platform.h
index 925df31f88..4a80057bdc 100644
--- a/OvmfPkg/XenPlatformPei/Platform.h
+++ b/OvmfPkg/XenPlatformPei/Platform.h
@@ -79,6 +79,11 @@ InstallClearCacheCallback (
   VOID
   );
 
+EFI_STATUS
+XenConnect (
+  VOID
+  );
+
 EFI_STATUS
 InitializeXen (
   VOID
diff --git a/OvmfPkg/XenPlatformPei/Platform.c b/OvmfPkg/XenPlatformPei/Platform.c
index 5809eadb0b..6aaafc3ee9 100644
--- a/OvmfPkg/XenPlatformPei/Platform.c
+++ b/OvmfPkg/XenPlatformPei/Platform.c
@@ -416,6 +416,8 @@ InitializeXenPlatform (
     CpuDeadLoop ();
   }
 
+  XenConnect ();
+
   BootModeInitialization ();
   AddressWidthInitialization ();
 
diff --git a/OvmfPkg/XenPlatformPei/Xen.c b/OvmfPkg/XenPlatformPei/Xen.c
index 2105304c41..29b42b746c 100644
--- a/OvmfPkg/XenPlatformPei/Xen.c
+++ b/OvmfPkg/XenPlatformPei/Xen.c
@@ -72,14 +72,11 @@ XenGetE820Map (
 /**
   Connects to the Hypervisor.
 
-  @param  XenLeaf     CPUID index used to connect.
-
   @return EFI_STATUS
 
 **/
 EFI_STATUS
 XenConnect (
-  UINT32 XenLeaf
   )
 {
   UINT32 Index;
@@ -91,7 +88,13 @@ XenConnect (
   UINT32 *PVHResetVectorData;
   RETURN_STATUS Status;
 
-  AsmCpuid (XenLeaf + 2, &TransferPages, &TransferReg, NULL, NULL);
+  ASSERT (mXenLeaf != 0);
+
+  //
+  // Prepare HyperPages to be able to make hypercalls
+  //
+
+  AsmCpuid (mXenLeaf + 2, &TransferPages, &TransferReg, NULL, NULL);
   mXenInfo.HyperPages = AllocatePages (TransferPages);
   if (!mXenInfo.HyperPages) {
     return EFI_OUT_OF_RESOURCES;
@@ -103,7 +106,11 @@ XenConnect (
                    (Index << EFI_PAGE_SHIFT) + Index);
   }
 
-  AsmCpuid (XenLeaf + 1, &XenVersion, NULL, NULL, NULL);
+  //
+  // Find out the Xen version
+  //
+
+  AsmCpuid (mXenLeaf + 1, &XenVersion, NULL, NULL, NULL);
   DEBUG ((DEBUG_ERROR, "Detected Xen version %d.%d\n",
           XenVersion >> 16, XenVersion & 0xFFFF));
   mXenInfo.VersionMajor = (UINT16)(XenVersion >> 16);
@@ -262,12 +269,6 @@ InitializeXen (
 {
   RETURN_STATUS PcdStatus;
 
-  if (mXenLeaf == 0) {
-    return EFI_NOT_FOUND;
-  }
-
-  XenConnect (mXenLeaf);
-
   //
   // Reserve away HVMLOADER reserved memory [0xFC000000,0xFD000000).
   // This needs to match HVMLOADER RESERVED_MEMBASE/RESERVED_MEMSIZE.
-- 
Anthony PERARD