linux-kernel - Re: [PATCH -v3] KVM: MCE: Add MCE support to KVM

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Message-ID: <4A1AE04F.9070808@siemens.com>
Date:	Mon, 25 May 2009 20:15:43 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Huang Ying <ying.huang@...el.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH -v3] KVM: MCE: Add MCE support to KVM

Avi Kivity wrote:
> Jan Kiszka wrote:
>> Avi Kivity wrote:
>>  
>>> Huang Ying wrote:
>>>    
>>>> The related MSRs are emulated. MCE capability is exported via
>>>> extension KVM_CAP_MCE and ioctl KVM_X86_GET_MCE_CAP_SUPPORTED.  A new
>>>> vcpu ioctl command KVM_X86_SETUP_MCE is used to setup MCE emulation
>>>> such as the mcg_cap. MCE is injected via vcpu ioctl command
>>>> KVM_X86_SET_MCE. Extended machine-check state (MCG_EXT_P) and CMCI are
>>>> not implemented.
>>>>
>>>>         
>>> Applied, thanks.
>>>
>>>     
>>
>> This patch breaks kvm build for 32-bit hosts.
>>   
> 
> Strange, I build-test on i386.  What's your failure?

This is against some 2.6.28 kernel:

  CC [M]  /data/kvm-kmod/x86/x86.o
/data/kvm-kmod/x86/x86.c: In function ‘set_msr_mce’:
/data/kvm-kmod/x86/x86.c:794: error: ‘MCG_CTL_P’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c:794: error: (Each undeclared identifier is reported only once
/data/kvm-kmod/x86/x86.c:794: error: for each function it appears in.)
/data/kvm-kmod/x86/x86.c: In function ‘get_msr_mce’:
/data/kvm-kmod/x86/x86.c:950: error: ‘MCG_CTL_P’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c: In function ‘kvm_arch_dev_ioctl’:
/data/kvm-kmod/x86/x86.c:1216: error: ‘MCG_CTL_P’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c: In function ‘kvm_vcpu_ioctl_x86_setup_mce’:
/data/kvm-kmod/x86/x86.c:1592: error: ‘MCG_CTL_P’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c: In function ‘kvm_vcpu_ioctl_x86_set_mce’:
/data/kvm-kmod/x86/x86.c:1613: error: ‘MCI_STATUS_VAL’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c:1619: error: ‘MCI_STATUS_UC’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c:1619: error: ‘MCG_CTL_P’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c:1630: error: ‘MCG_STATUS_MCIP’ undeclared (first use in this function)
/data/kvm-kmod/x86/x86.c:1639: error: ‘MCI_STATUS_OVER’ undeclared (first use in this function)

> 
>> Is the KVM MCE interface completely or only partially limited to x86-64,
>> ie. can I completely #ifdef it away on 32-bit hosts (including
>> KVM_CAP_MCE) or is this more complicated?
>>   
> 
> I don't see any reason to limit it to x86_64?
> 

Well, if I look at the definition of MCI_STATUS_VAL as (1UL<<63),
something tells me: "Hey, only use me on 64-bit hosts!" But I have no
clue about details of this stuff, and from a second glance at it is
seems to include at least some parts that are valid on 32-bit as well.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
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