From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wanpeng Li <wanpeng.li@linux.intel.com>
Subject: Re: [PATCH] KVM: VMX: Preserve host CR4.MCE value while in guest
 mode.
Date: Mon, 20 Apr 2015 06:59:13 +0800
Message-ID: <20150419225913.GA8627@kernel>
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 <20150417051007.GA3080@kernel>
 <5530DD72.7010801@redhat.com>
Reply-To: Wanpeng Li <wanpeng.li@linux.intel.com>
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Cc: Ben Serebrin <serebrin@google.com>, kvm@vger.kernel.org,
	stable@vger.kernel.org, luto@amacapital.net, jankiszka@siemens.com
To: Paolo Bonzini <pbonzini@redhat.com>
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On Fri, Apr 17, 2015 at 12:16:18PM +0200, Paolo Bonzini wrote:
>
>
>On 17/04/2015 07:10, Wanpeng Li wrote:
>>> >
>>> >Before the change, if guest CR4.MCE==0, then the machine check is
>>> >escalated to Catastrophic Error (CATERR) and the machine dies.
>> Could you point out which section of SDM describes that the machine check 
>> is escalated to a CATERR if CR4.MCE==0?
>
>It's under the description of "Interrupt 18--Machine-Check Exception (#MC)":
>
>   The machine-check mechanism is enabled by setting the MCE flag in
>   control register CR4.  [...] If the machine-check mechanism is not
>   enabled (the MCE flag in control register CR4 is clear), a
>   machine-check exception causes the processor to enter the shutdown
>   state.
>
>This of course also applies whenever the non-root mode CR4 (*not* the
>shadow CR4 in the VMCS!) has the MCE flag cleared.

Got it, thanks, :)

Regards,
Wanpeng Li 

>
>Paolo