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

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Mon, 20 Apr 2009 12:05:26 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Gerd Hoffmann <kraxel@...hat.com>
CC:	Anthony Liguori <anthony@...emonkey.ws>,
	Huang Ying <ying.huang@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH] Add MCE support to KVM

Gerd Hoffmann wrote:
> On 04/20/09 10:26, Avi Kivity wrote:
>> Gerd Hoffmann wrote:
>>> The xen pv-on-hvm drivers use an msr to indicate "please place the
>>> hypercall page here". Handling that in kernel isn't an option IMHO.
>>
>> The contents of the hypercall page are vendor specific. This can be
>> handled from userspace (though ideally we'd abstract the cpu vendor
>> away).
>
> Well, xenner doesn't do vmcalls, so the page isn't vendor specific.  

Well, for true pv (not pv-on-hvm) it wouldn't use the MSR, would it?

> It looks different for 32bit / 64bit guests though.  And it actually 
> can be multiple pages (with one msr write per page).  So the interface 
> for in-kernel handling would be more complex than "here is a hypercall 
> page for you".

To different MSRs, or multiple writes to the same MSR?

>
> > The Hyper-V hypercall page is more problematic, as it's specified to 
> > be an overlay; the page doesn't have to exist in guest RAM.
>
> In userspace it should be easy to handle though as qemu can just 
> create a new memory slot, right?

It depends if the MSR may be considered global, or is required to be 
per-cpu.  Need to refresh my memory on this, but I remember reading this 
and saying 'yuck'.

-- 
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/