Re: FW: Wrt golden MMIO/CFG snaphot in GVT-g

From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: "Wang, Zhi A" <zhi.a.wang@intel.com>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>
Cc: "Vetter, Daniel" <daniel.vetter@intel.com>,
	"Lv, Zhiyuan" <zhiyuan.lv@intel.com>
Subject: Re: FW: Wrt golden MMIO/CFG snaphot in GVT-g
Date: Fri, 27 May 2016 14:32:25 +0300	[thread overview]
Message-ID: <1464348745.6972.9.camel@linux.intel.com> (raw)
In-Reply-To: <F3B0350DF4CB6849A642218320DE483D4B972048@SHSMSX101.ccr.corp.intel.com>

On pe, 2016-05-27 at 10:05 +0000, Wang, Zhi A wrote:
> For me I think maybe i915 could save the snapshot for GVT, then GVT-g 
> patch the snapshot itself, then there won’t be leaking happened I
> think. Even we wrote a dedicated little program, we would do the same
> thing.
>  
> From: Wang, Zhi A 
> Sent: Friday, May 27, 2016 12:59 PM
> To: joonas.lahtinen@linux.intel.com; 'Chris Wilson' ; Vetter, Daniel <daniel.vetter@intel.com>; tvrtko.ursulin@linux.intel.com
> Cc: Tian, Kevin <kevin.tian@intel.com>; Lv, Zhiyuan 
> Subject: Wrt golden MMIO/CFG snaphot in GVT-g
>  
> Hi Guys:
> I received some comments on from Kevin. Mostly his concern is the
> burden of maintain/releasing the MMIO/CFG snapshot for customers. As
> we might not have all the SKUs/platform which customers have, even we
> release the snapshot file generator for customer, it would still
> bring some extra effort when customer deploying the SW. And he
> suggested i915 better i915 could keep the snapshot for GVT-g during
> module loading.

It will be much harder to ask everyone else in addition to those with
odd hardware revisions to provide the boot-captured register state for
each bug they report. I do not feel adding some extra (one-time!)
effort for customers deploying on weird SKUs overcomes that everyone
would have to provide a register dump for each bug.

So I am still very much against making a register freeze at each boot.
Even creating a one-shot golden state automatically when one is found
missing the SKU from firmware package and then using that each time
would make the system operation more stable. It should not be too hard
to instruct customer to do that?

Regards, Joonas

> As we have shared some ideas about the security problem like leaking
> BIOS configuration to VM, better we could elaborate more ideas and
> figure out a better approach. Let’s discuss. J
>  
> Thanks,
> Zhi.
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation

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