[Xen-devel] [PATCH] hvm: live migration between intel and amd

[Jean Guyader <jean.guyader@xxxxxxxxxxxxx>]

Hi,


This patch is to enable live migration (save/restore) between intel and 
amd processor. We need to downgrade the cpuid to make it look like a P3.
The downgrading don't induce any huge performance impacts (enclosed 
graphs of ddk build on windows 2k3, build -c -ZPM 3).
Please try it by yourself to give me some feedback.

Regards,

--
Jean Guyader

diff -r ec56331c056a xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Thu Jun 12 16:34:25 2008 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Fri Jun 13 16:40:30 2008 +0100
@@ -614,6 +614,23 @@ static void vmx_load_cpu_state(struct vc
 {
 #ifdef __x86_64__
     struct vmx_msr_state *guest_state = &v->arch.hvm_vmx.msr_state;
+
+    /* Do we come from AMD processor ? */
+    if ( data->msr_flags == -1ULL )
+    {
+        data->msr_flags = 0x7ULL;
+
+        data->ldtr_limit = 0xffffffff;
+        data->ldtr_arbytes = 0xc00;
+
+        data->cs_arbytes = 0xc9b;
+
+        data->gs_limit = 0xffffffff;
+        data->gs_arbytes = 0xc00;
+
+        data->tr_arbytes = 0x8b;
+    }
+
 
     /* restore msrs */
     guest_state->flags = data->msr_flags;

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