linux-kernel - Re: [RFC/RFT] Add noats flag to boot parameters

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Message-ID: <20180503133459.waawna3ebtu3udn6@8bytes.org>
Date:   Thu, 3 May 2018 15:35:00 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Gil Kupfer <gilkup@...il.com>
Cc:     dwmw2@...radead.org, bhelgaas@...gle.com,
        iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, nadav.amit@...il.com,
        Gil Kupfer <gilkup@...technion.ac.il>
Subject: Re: [RFC/RFT] Add noats flag to boot parameters

On Sun, Apr 29, 2018 at 09:16:48PM +0300, Gil Kupfer wrote:
> This patch adds noats option to the pci boot parameter.
> When noats is selected, all ATS related functions fail immediately and
> the IOMMU is configured to not use device-iotlb.
> 
> Any function that checks for ATS capabilities directly against the
> devices should also check this flag. (Currently, such functions exist
> only in IOMMU drivers, and they are covered by this patch.)
> 
> The motivation behind this patch is the existence of malicious devices.
> Lots of research has been done about how to utilitize the IOMMU as a
> protection from such devices. When ATS is supported, any I/O device can
> access any physical access by faking device-IOTLB entries.
> Adding the ability to ignore these entries lets sysadmins enhance system
> security.
> 
> Signed-off-by: Gil Kupfer <gilkup@...technion.ac.il>

This has also been on my list, thanks for doing that.

Acked-by: Joerg Roedel <jroedel@...e.de>