Re: [PATCH] KVM: Add missing emulation failure report in kvm_mmu_page_fault()

[Avi Kivity <avi@redhat.com>]

On 01/18/2010 11:32 AM, Sheng Yang wrote:
> On Sunday 17 January 2010 20:34:23 Avi Kivity wrote:
>    
>> On 01/15/2010 10:44 AM, Sheng Yang wrote:
>>      
>>> Currently we only have handle_invalid_guest_state() reported emulation
>>> failure...
>>>        
>> This is intentional - instead of spamming dmesg, we exit with an
>> internal error.  Modern qemu-kvm will halt and allow the user to inspect
>> the guest with the built-in disassembler.
>>
>>      
> I think keep it there still useful for some users. And we have the same report
> in handle_invalid_guest_state(), and we even have "emulation failure, check
> dmesg for details" in QEmu when handling KVM_INTERNAL_ERROR_EMULATION.
>
> I think add one line here is the easiest way to keep consistence, and is
> handy.
>    

Another way to keep consistency is to remove emulation failure reporting 
in handle_invalid_guest_state() :)

There are two problems with the kernel failure report.  First, it 
doesn't report enough data - registers, surrounding instructions, etc. 
that are needed to explain what is going on.  Second, it can flood 
dmesg, which is a pretty bad thing to do.

I have a patch somewhere that adds instruction emulation bytes (both 
successful and failed) to ftrace.  That may be useful, perhaps.

-- 
error compiling committee.c: too many arguments to function