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[Xen-devel] Re: [RFC] xsave/xrstor: changes to the struct vcpu_guest_con

To: "Cui, Dexuan" <dexuan.cui@xxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxxxx>
Subject: [Xen-devel] Re: [RFC] xsave/xrstor: changes to the struct vcpu_guest_context
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Tue, 11 Aug 2009 11:48:27 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Zhai, Edwin" <edwin.zhai@xxxxxxxxx>
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Thread-topic: [RFC] xsave/xrstor: changes to the struct vcpu_guest_context
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On 11/08/2009 11:07, "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:

> 1)  define a new struct vcpu_guest_context_new: its first feild is the legacy
> struct vcpu_guest_context and the other is the new xsave field;
> 2) add a new flag (a new bit definition) VGCF_xsave_valid to the existing
> 'flags' field;

Looks like a kludge. Quite apart from the fact that messing with
vcpu_guest_contexrt is a pita because its format differs between 32-bit and
64-bit callers/guests.

Instead, I suggest to simply make new domctls to get/set xsave state in its
raw format. That same format can be introduced as a new 'chunk' in HVM save
files too, and can automatically be included when making the 'hvm save'
hypercall. By raw format I mean exactly the format produced by XSAVE, albeit
perhaps excluding the first 512 'legacy' bytes.

 -- Keir

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