linux-kernel - Re: [PATCH 0/2] iommu/vt-d: Keep RMRR mappings around on driver unbind

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Message-ID: <20141002003038.GA30672@anatevka.fc.hp.com>
Date:	Wed, 1 Oct 2014 18:30:38 -0600
From:	Jerry Hoemann <jerry.hoemann@...com>
To:	Joerg Roedel <joro@...tes.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	iommu@...ts.linux-foundation.org, jroedel@...e.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] iommu/vt-d: Keep RMRR mappings around on driver
 unbind

On Tue, Sep 30, 2014 at 01:02:01PM +0200, Joerg Roedel wrote:
> Hi,
> 
> here is a patch-set to fix an issue recently discovered when
> the Intel IOMMU is in use with devices that need RMRR
> mappings.
> 
> The problem is that the RMRR mappings are destroyed when the
> device driver is unbound from the device, causing DMAR
> faults.
> 
> To solve this problem a device driver core change is
> necessary to catch the right point in time for the IOMMU
> code to destroy any mappings for a device.
> 
> With this patch-set the RMRR mappings are only destroyed
> when the device is actually removed from the system.
> 
> Please review.
> 
> Thanks,
> 
> 	Joerg
> 
> Joerg Roedel (2):
>   driver core: Add BUS_NOTIFY_REMOVED_DEVICE event
>   iommu/vt-d: Only remove domain when device is removed
> 
>  drivers/base/core.c         |  3 +++
>  drivers/iommu/intel-iommu.c | 11 +----------
>  include/linux/device.h      | 11 ++++++-----
>  3 files changed, 10 insertions(+), 15 deletions(-)
> 
> -- 
> 1.9.1


Joerg,

I tested on HP Gen7 and Gen9 systems for which we experience dmar faults
when we rmmod a driver whose device had RMRR regions associated with it.

We don't see problem when patch set is applied.

Thanks,

Tested-by: Jerry Hoemann <jerry.hoemann@...com>

-- 

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Jerry Hoemann            Software Engineer              Hewlett-Packard

3404 E Harmony Rd. MS 36                        phone:  (970) 898-1022
Ft. Collins, CO 80528                           FAX:    (970) 898-0707
                                                email:  jerry.hoemann@...com
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