linux-kernel - Re: [PATCH v2] iommu/vt-d: Turn off translations at shutdown

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:   Sun, 10 Nov 2019 19:21:45 -0800
From:   Deepa Dinamani <deepa.kernel@...il.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        joro@...tes.org, David Woodhouse <dwmw2@...radead.org>,
        iommu@...ts.linux-foundation.org
Subject: Re: [PATCH v2] iommu/vt-d: Turn off translations at shutdown

On Sun, Nov 10, 2019 at 5:35 PM Lu Baolu <baolu.lu@...ux.intel.com> wrote:
>
> Hi,
>
> On 11/11/19 1:27 AM, 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.
>
> Do you mind shining more light on this statement? I can't get your point
> here. Currently iommu_shutdown() only happens for reboot, right?

In this part, I'm saying that I'm leaving intel_iommu_init() alone.
I'm not taking out disabling the iommu from intel_iommu_init(). This
will help when BIOS has enabled the IOMMU and for whatever reason, the
kernel is booting with IOMMU off.

-Deepa