linux-kernel - RE: [PATCH v3] Prevent devices with RMRRs from being placed into SI Domain during startup

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Message-ID: <9774516974AF5F4C8A2C3C69CD341233233C1A2E@G1W3651.americas.hpqcorp.net>
Date:	Tue, 16 Oct 2012 17:38:47 +0000
From:	"Mingarelli, Thomas" <Thomas.Mingarelli@...com>
To:	Alex Williamson <alex.williamson@...hat.com>
CC:	David Woodhouse <dwmw2@...radead.org>,
	Don Dutile <ddutile@...hat.com>,
	"Khan, Shuah" <shuah.khan@...com>,
	"Knippers, Linda" <linda.knippers@...com>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3] Prevent devices with RMRRs from being placed into SI
 Domain during startup

I only perform this action on startup because that is the first time the devices are placed into the SI Domain when passthrough mode is used. If they never make it into the SI Domain then there is no RMRR confusion to worry about.


Tom

-----Original Message-----
From: Alex Williamson [mailto:alex.williamson@...hat.com] 
Sent: Tuesday, October 16, 2012 12:00 PM
To: Mingarelli, Thomas
Cc: David Woodhouse; Don Dutile; Khan, Shuah; Knippers, Linda; iommu@...ts.linux-foundation.org; linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] Prevent devices with RMRRs from being placed into SI Domain during startup

On Tue, 2012-10-16 at 16:50 +0000, Tom Mingarelli wrote:
> This patch is to prevent devices that have RMRRs associated with them 
> from getting placed into the SI Domain during init. We don't put USB devices
> into this category, however. This fixes the issue where the RMRR info
> for devices being placed in and out of the SI Domain gets lost.
> 
> Signed-off-by: Thomas Mingarelli <thomas.mingarelli@...com>
> ----
> PATCH v1: https://lkml.org/lkml/2012/6/15/204
> PATCH v2: https://lkml.org/lkml/2012/9/18/354
> 
> drivers/iommu/intel-iommu.c |   33 +++++++++++++++++++++++++++++++++
> 1 files changed, 33 insertions(+), 0 deletions(-)
> 
> diff -up ./drivers/iommu/intel-iommu.c.ORIG ./drivers/iommu/intel-iommu.c
> --- ./drivers/iommu/intel-iommu.c.ORIG	2012-10-16 09:34:23.148089944 -0500
> +++ ./drivers/iommu/intel-iommu.c	2012-10-16 09:56:56.905932861 -0500
> @@ -2320,8 +2320,41 @@ static int domain_add_dev_info(struct dm
>  	return 0;
>  }
>  
> +static bool device_has_rmrr(struct pci_dev *dev)
> +{
> +	struct dmar_rmrr_unit *rmrr;
> +	int i;
> +
> +	for_each_rmrr_units(rmrr) {
> +		for (i = 0; i < rmrr->devices_cnt; i++) {
> +			/*
> +			 * Here we are just concerned with checking each device
> +			 * that has an RMRR associated with it and not allow it
> +			 * to be placed into the SI Domain during startup.
> +			*/
> +			if (rmrr->devices[i] == dev)
> +				return true;
> +		}
> +	}
> +	return false;
> +}
> +
>  static int iommu_should_identity_map(struct pci_dev *pdev, int startup)
>  {
> +
> +	if (startup) {
> +		/*
> +		 * This is where we will refuse any device that has an
> +		 * RMRR associated with it and is not a USB device and
> +		 * NOT allow it to be placed into the SI Domain. We
> +		 * only do this on startup.

Why only on startup?

>  We don't need a separate bit
> +		 * for this because it could be ANY device.
> +		*/

Note the white space here doesn't match existing comment blocks in
intel-iommu.

> +		if (device_has_rmrr(pdev) &&
> +			(pdev->class >> 8) != PCI_CLASS_SERIAL_USB)
> +				return 0;
> +	}
> +
>  	if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
>  		return 1;
>  

Thanks,
Alex