Messages in this thread | | | From | "Zeng, Jason" <> | Subject | RE: [PATCH] intel-iommu: Turn off translations at shutdown | Date | Fri, 8 Nov 2019 08:47:19 +0000 |
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> -----Original Message----- > From: David Woodhouse <dwmw2@infradead.org> > Sent: Friday, November 8, 2019 3:54 PM > To: Deepa Dinamani <deepa.kernel@gmail.com>; joro@8bytes.org; linux- > kernel@vger.kernel.org > Cc: iommu@lists.linux-foundation.org; Zeng, Jason <jason.zeng@intel.com>; > Tian, Kevin <kevin.tian@intel.com> > Subject: Re: [PATCH] intel-iommu: Turn off translations at shutdown > > On Thu, 2019-11-07 at 12:59 -0800, Deepa Dinamani wrote: > > The intel-iommu driver assumes that the iommu state is > > cleaned up at the start of the new kernel. > > But, when we try to kexec boot something other than the > > Linux kernel, the cleanup cannot be relied upon. > > Hence, cleanup before we go down for reboot. > > > > Keeping the cleanup at initialization also, in case BIOS > > leaves the IOMMU enabled. > > > > I considered turning off iommu only during kexec reboot, > > but a clean shutdown seems always a good idea. But if > > someone wants to make it conditional, we can do that. > > This is going to break things for the VMM live update scheme that Jason > presented at KVM Forum, isn't it? > > In that case we rely on the IOMMU still operating during the > transition.
For VMM live update case, we should be able to detect and bypass the shutdown that Deepa introduced here, so keep IOMMU still operating?
Thanks, Jason
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