[Xen-changelog] [xen-unstable] x86 hvm: Allow restore of old images with different segment attribute format.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1234517392 0
# Node ID e6f1c66874d55fcf76ebdd4130ba55a3c8952b55
# Parent  726b56720b16e5e0effe24fbddac78d8af4c2125
x86 hvm: Allow restore of old images with different segment attribute format.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c |   16 ++++++++++++++++
 1 files changed, 16 insertions(+)

diff -r 726b56720b16 -r e6f1c66874d5 xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Fri Feb 13 11:23:16 2009 +0900
+++ b/xen/arch/x86/hvm/hvm.c    Fri Feb 13 09:29:52 2009 +0000
@@ -542,6 +542,22 @@ static int hvm_load_cpu_ctxt(struct doma
         return -EINVAL;
     }
 
+    /* Older Xen versions used to save the segment arbytes directly 
+     * from the VMCS on Intel hosts.  Detect this and rearrange them
+     * into the struct segment_register format. */
+#define UNFOLD_ARBYTES(_r)                          \
+    if ( (_r & 0xf000) && !(_r & 0x0f00) )          \
+        _r = ((_r & 0xff) | ((_r >> 4) & 0xf00))
+    UNFOLD_ARBYTES(ctxt.cs_arbytes);
+    UNFOLD_ARBYTES(ctxt.ds_arbytes);
+    UNFOLD_ARBYTES(ctxt.es_arbytes);
+    UNFOLD_ARBYTES(ctxt.fs_arbytes);
+    UNFOLD_ARBYTES(ctxt.gs_arbytes);
+    UNFOLD_ARBYTES(ctxt.ss_arbytes);
+    UNFOLD_ARBYTES(ctxt.tr_arbytes);
+    UNFOLD_ARBYTES(ctxt.ldtr_arbytes);
+#undef UNFOLD_ARBYTES
+
     /* Architecture-specific vmcs/vmcb bits */
     if ( hvm_funcs.load_cpu_ctxt(v, &ctxt) < 0 )
         return -EINVAL;

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