RE: [PATCH] intel-iommu: Turn off translations at shutdown

From: "Zeng, Jason" <jason.zeng@intel.com>
To: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"rminnich@google.com" <rminnich@google.com>,
	"Zeng, Jason" <jason.zeng@intel.com>
Subject: RE: [PATCH] intel-iommu: Turn off translations at shutdown
Date: Mon, 11 Nov 2019 02:35:38 +0000	[thread overview]
Message-ID: <8D8B600C3EC1B64FAD4503F0B66C61F23BC208@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <CABeXuvrYzLoc7YGtmXDJqEovwyERbndN4cC6UaYAw5+qABRr8A@mail.gmail.com>

> -----Original Message-----
> On Sun, Nov 10, 2019 at 10:24 AM Deepa Dinamani
> > I've posted the v2 without the conditional for now:
> > https://lore.kernel.org/patchwork/patch/1151225/
> >
> > As a side topic, I'm trying to support https://www.linuxboot.org/. I
> > have a couple of more such cleanups coming. The VMM live updates and
> > linuxboot seem to have contradicting requirements and they both use
> > kexec. So kexec_in_progress doesn't seem like a sufficient indicator
> > to distinguish between the two. Do you already have an idea on how to
> > distiguish between them? Does a separate sys_reboot() command
> > parameter sound ok? Or, we could use the flags in the sys_kexec_load()
> > depending on how the live update feature is implemented.
> 
> Also, the AMD driver disables iommu at shutdown already. So the live update
> feature is already broken on AMD.
> 

Hi Deepa,

I think you may not need to consider too much VMM live update here (although it
would be good to consider possible future features), after all it is an on-going effort,
we are still not quite sure what exact modifications it needs. The VMM live update
itself will figure out what is the best way to modify the code.

Thanks,
Jason

> -Deepa