linux-kernel - Re: [PATCH 2/3] kvmclock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 13 Nov 2007 16:44:43 +0200
From:	Avi Kivity <avi@...ranet.com>
To:	Glauber de Oliveira Costa <gcosta@...hat.com>
CC:	linux-kernel@...r.kernel.org, jeremy@...p.org, aliguori@...ibm.com,
	kvm-devel@...ts.sourceforge.net, hollisb@...ibm.com
Subject: Re: [PATCH 2/3] kvmclock - the host part.

Glauber de Oliveira Costa wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Avi Kivity escreveu:
>   
>> Glauber de Oliveira Costa wrote:
>>     
>>> This is the host part of kvm clocksource implementation. As it does
>>> not include clockevents, it is a fairly simple implementation. We
>>> only have to register a per-vcpu area, and start writting to it
>>> periodically.
>>>
>>>   
>>>       
>> Missing live migration support  (a way for userspace to read and write
>> the guest clock address).  Should probably be in a separate patch.
>>     
>
> I think it's a matter of issuing a hypercall for reading the clock
> address. It's fair simple, and can be done in a later version of this patch.
> As for writting, the register hypercall itself can be used. It has no
> special side-effects we should care about.
>   

kvm live migration is done (at least thus far) without guest 
involvement.  So you need the host to be able to transfer this state.


>   
>>> @@ -1924,6 +1955,7 @@ out:
>>>          goto preempted;
>>>      }
>>>  
>>> +    kvm_write_guest_time(vcpu);
>>>      post_kvm_run_save(vcpu, kvm_run);
>>>   
>>>       
>> Why here?  Seems like we're leaving the guest for a while at this place.
>>
>> Suggest putting it on top of __vcpu_run(), guarded by a flag, and
>> setting the flag every time we put the vcpu.
>>     
>
> No special preference. It just sounded exity enough to me. I can move to
> where you suggest.
>
>   

It's more than a place, it's a set of rules:

- if the vcpu is migrated, we need a new timebase
- ditto if we're descheduled (well that's the same thing)
- if "some time passes"


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

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/