From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH] KVM: x86: remove vcpu's CPL check in host invoked vcpu's
 xcr set process
Date: Mon, 17 Jun 2013 17:38:50 +0200
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References: <D3E216785288A145B7BC975F83A2ED103FEAC791@szxeml556-mbx.china.huawei.com>
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Cc: KVM <kvm@vger.kernel.org>, "mst@redhat.com" <mst@redhat.com>,
	Luonengjun <luonengjun@huawei.com>,
	Zanghongyong <zanghongyong@huawei.com>,
	"Huangweidong (C)" <weidong.huang@huawei.com>,
	"Wangrui (K)" <moon.wangrui@huawei.com>
To: "Zhanghaoyu (A)" <haoyu.zhang@huawei.com>
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Il 14/06/2013 09:36, Zhanghaoyu (A) ha scritto:
> __kvm_set_xcr function does the CPL check when set xcr. __kvm_set_xcr is called in two flows,
> one is invoked by guest, call stack shown as below,
> handle_xsetbv(or xsetbv_interception)
>   kvm_set_xcr
>     __kvm_set_xcr
> the other one is invoked by host(QEMU), call stack shown as below,
> kvm_arch_vcpu_ioctl
>   kvm_vcpu_ioctl_x86_set_xcrs
>     __kvm_set_xcr
> 
> The former does need the CPL check, but the latter does not.
> 
> Signed-off-by: Zhang Haoyu <haoyu.zhang@huawei.com>

What does this patch fix?  I suppose it is some kind of migration
problem since you mentioned QEMU, but I'd rather be sure.  I can fix the
commit message myself when applying.

Thanks,

Paolo