[PATCH 4/4] Dom0: extend fpu_ctxt to consist with Xen hypervisor

[PATCH 4/4] Dom0: extend fpu_ctxt to consist with Xen hypervisor

[Han, Weidong]

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fpu_ctxt must be consistent between Dom0 and Xen hypervisor. Otherwise, dom0 cannot boot up.

Signed-off-by: Weidong Han <weidong.han@intel.com>

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From a8db3ba7be721306d435e313049c29b7ba48fa3f Mon Sep 17 00:00:00 2001
From: Weidong Han <weidong.han@intel.com>
Date: Fri, 27 Aug 2010 10:14:16 -0400
Subject: [PATCH] Extend fpu_ctxt to consist with Xen hypervisor

fpu_ctxt must be consistent between Dom0 and Xen hypervisor.
Otherwise, dom0 cannot boot up.

Signed-off-by: Weidong Han <weidong.han@intel.com>
---
 arch/x86/include/asm/xen/interface.h |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/xen/interface.h b/arch/x86/include/asm/xen/interface.h
index 9539998..5e18534 100644
--- a/arch/x86/include/asm/xen/interface.h
+++ b/arch/x86/include/asm/xen/interface.h
@@ -124,11 +124,16 @@ struct arch_shared_info {
 #ifndef __ASSEMBLY__
 /*
  * The following is all CPU context. Note that the fpu_ctxt block is filled
- * in by FXSAVE if the CPU has feature FXSR; otherwise FSAVE is used.
+ * in by XSAVE if the CPU has feature XSAVE, otherwise use FXSAVE if the CPU
+ * has feature FXSR; otherwise FSAVE is used.
  */
 struct vcpu_guest_context {
-    /* FPU registers come first so they can be aligned for FXSAVE/FXRSTOR. */
-    struct { char x[512]; } fpu_ctxt;       /* User-level FPU registers     */
+    /*
+     * FPU registers come first so they can be aligned for
+     * FXSAVE/FXRSTOR and XSAVE/XRSTOR. Using 4096 Bytes for
+     * future state extensions
+     */
+    struct { char x[4096]; } fpu_ctxt;       /* User-level FPU registers     */
 #define VGCF_I387_VALID (1<<0)
 #define VGCF_HVM_GUEST  (1<<1)
 #define VGCF_IN_KERNEL  (1<<2)
-- 
1.6.0.4


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Re: [PATCH 4/4] Dom0: extend fpu_ctxt to consist with Xen hypervisor

[Christoph Egger]

On Tuesday 31 August 2010 05:00:02 Han, Weidong wrote:
> fpu_ctxt must be consistent between Dom0 and Xen hypervisor. Otherwise,
> dom0 cannot boot up.
>
> Signed-off-by: Weidong Han <weidong.han@intel.com>

How does this guarantee backward compatibility ?

Christoph


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Re: [PATCH 4/4] Dom0: extend fpu_ctxt to consist with Xen hypervisor

[Weidong Han]

Christoph Egger wrote:
> On Tuesday 31 August 2010 05:00:02 Han, Weidong wrote:
>   
>> fpu_ctxt must be consistent between Dom0 and Xen hypervisor. Otherwise,
>> dom0 cannot boot up.
>>
>> Signed-off-by: Weidong Han <weidong.han@intel.com>
>>     
>
> How does this guarantee backward compatibility ?
>
> Christoph
>
>   
yes. it is not backward compatible. I will re-implement it.

Regards,
Weidong