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From: "Jan Beulich" <JBeulich@suse.com>
To: Xudong Hao <xudong.hao@intel.com>
Cc: Haozhong Zhang <haozhong.zhang@intel.com>,
	Wei Liu <wei.liu2@citrix.com>,
	Xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: live migration from new platform to old platform
Date: Tue, 07 Jun 2016 01:38:49 -0600	[thread overview]
Message-ID: <5756962902000078000F2714@prv-mh.provo.novell.com> (raw)
In-Reply-To: <B8376D2DEA074F45BA033984477C453E034ACC47@shsmsx102.ccr.corp.intel.com>

>>> On 07.06.16 at 09:02, <xudong.hao@intel.com> wrote:
> Guessing HVM context of some new instruction can't be restored to an old 
> platform. Current Xen xl has cupid parameter parsing implement "cupid" in 
> guest config, like 
> cupid='host,xsave=0'
> or
> cpuid=[ '1:ecx=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx0' ]
> 
> So I tried to disable some new cupid in guest config, both of the two below 
> method doesn't work, the HVM guest didn't disable those cupid such as "hle, 
> rtm, rdseed...".
> cpuid='host,3dnowprefetch=0,hle=0,rtm=0,rdseed=0,adx=0,smap=0'
> cpuid=['7:ebx=xxxxxxxxxxx000xxxxxx0xxxxxx0xxxx']

This derivation of yours doesn't look right: Leaf 7 requires a sub-leaf
to be specified (I don't recall off the top of my head what the exact
syntax is). So I first of all wonder - did you verify that your CPUID
adjustments actually too effect (in the sense of making it into
d->arch.cpuids[])? Because once there, I can't see how the guest
could get presented anything other than those values.

Jan


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  reply	other threads:[~2016-06-07  7:38 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-07  7:02 live migration from new platform to old platform Hao, Xudong
2016-06-07  7:38 ` Jan Beulich [this message]
2016-06-07  8:40   ` Hao, Xudong
2016-06-07  9:46 ` Andrew Cooper
2016-06-08  2:08   ` Hao, Xudong

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