[Xen-devel] [PATCH v2 21/31] OvmfPkg/XenPlatformPei: Get E820 table via hypercall ...

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

.. when hvmloader haven't runned before OVMF. The only way left to get
an E820 table is to ask Xen via an hypercall, the call can only be made
once so keep the result cached for later.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 OvmfPkg/XenPlatformPei/Xen.c | 46 +++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/OvmfPkg/XenPlatformPei/Xen.c b/OvmfPkg/XenPlatformPei/Xen.c
index 23ff3102b5..f8cee671d8 100644
--- a/OvmfPkg/XenPlatformPei/Xen.c
+++ b/OvmfPkg/XenPlatformPei/Xen.c
@@ -33,6 +33,7 @@
 #include <Library/MtrrLib.h>
 #include <IndustryStandard/Xen/arch-x86/hvm/start_info.h>
 #include <Library/XenHypercallLib.h>
+#include <IndustryStandard/Xen/memory.h>
 
 #include "Platform.h"
 #include "Xen.h"
@@ -46,6 +47,8 @@ EFI_XEN_INFO mXenInfo;
 // Only the E820 table is used by OVMF.
 //
 EFI_XEN_OVMF_INFO *mXenHvmloaderInfo;
+EFI_E820_ENTRY64 E820Entries[128];
+UINT32 E820EntriesCount;
 
 /**
   Returns E820 map provided by Xen
@@ -61,6 +64,12 @@ XenGetE820Map (
   UINT32 *Count
   )
 {
+  INTN ReturnCode;
+  xen_memory_map_t Parameters;
+  UINTN LoopIndex;
+  UINTN Index;
+  EFI_E820_ENTRY64 TmpEntry;
+
   //
   // Get E820 produced by hvmloader
   //
@@ -72,7 +81,42 @@ XenGetE820Map (
     return EFI_SUCCESS;
   }
 
-  return EFI_NOT_FOUND;
+  //
+  // Otherwise, get the E820 table from the Xen hypervisor
+  //
+
+  if (E820EntriesCount > 0) {
+    *Entries = E820Entries;
+    *Count = E820EntriesCount;
+    return EFI_SUCCESS;
+  }
+
+  Parameters.nr_entries = 128;
+  set_xen_guest_handle (Parameters.buffer, E820Entries);
+
+  // Returns a errno
+  ReturnCode = XenHypercallMemoryOp (XENMEM_memory_map, &Parameters);
+  ASSERT (ReturnCode == 0);
+
+  E820EntriesCount = Parameters.nr_entries;
+
+  //
+  // Sort E820 entries
+  //
+  for (LoopIndex = 1; LoopIndex < E820EntriesCount; LoopIndex++) {
+    for (Index = LoopIndex; Index < E820EntriesCount; Index++) {
+      if (E820Entries[Index - 1].BaseAddr > E820Entries[Index].BaseAddr) {
+        TmpEntry = E820Entries[Index];
+        E820Entries[Index] = E820Entries[Index - 1];
+        E820Entries[Index - 1] = TmpEntry;
+      }
+    }
+  }
+
+  *Count = E820EntriesCount;
+  *Entries = E820Entries;
+
+  return EFI_SUCCESS;
 }
 
 /**
-- 
Anthony PERARD


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