linux-kernel - Re: [PATCH v4] intel-iommu: Prevent devices with RMRRs from being placed into SI Domain

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Date:	Tue, 20 Nov 2012 13:19:24 -0700
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Tom Mingarelli <thomas.mingarelli@...com>
Cc:	Don Dutile <ddutile@...hat.com>,
	Linda Knippers <linda.knippers@...com>,
	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Shuah Khan <shuah.khan@...com>,
	David Woodhouse <dwmw2@...radead.org>,
	Joerg Roedel <joro@...tes.org>
Subject: Re: [PATCH v4] intel-iommu: Prevent devices with RMRRs from being
 placed into SI Domain

On Tue, 2012-11-20 at 19:43 +0000, Tom Mingarelli wrote:
> This patch is to prevent non-USB devices that have RMRRs associated with them from
> being placed into the SI Domain during init. 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>
> Tested-by: Shuah Khan <shuah.khan@...com>
> ---
> PATCH v1: https://lkml.org/lkml/2012/6/15/204
> PATCH v2: https://lkml.org/lkml/2012/9/18/354
> PATCH v3: https://lkml.org/lkml/2012/10/16/375
> 
>  drivers/iommu/intel-iommu.c |   31 +++++++++++++++++++++++++++++++
>  1 files changed, 31 insertions(+), 0 deletions(-)

Looks ok to me.

Reviewed-by: Alex Williamson <alex.williamson@...hat.com>

> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index d4a4cd4..8c064df 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -2320,8 +2320,39 @@ static int domain_add_dev_info(struct dmar_domain *domain,
>  	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++) {
> +			/*
> +			 * Return TRUE if this RMRR contains the device that
> +			 * is passed in.
> +			 */
> +			if (rmrr->devices[i] == dev)
> +				return true;
> +		}
> +	}
> +	return false;
> +}
> +
>  static int iommu_should_identity_map(struct pci_dev *pdev, int startup)
>  {
> +
> +	/*
> +	 * We want to prevent any device associated with an RMRR from
> +	 * getting placed into the SI Domain. This is done because
> +	 * problems exist when devices are moved in and out of domains
> +	 * and their respective RMRR info is lost. We exempt USB devices
> +	 * from this process due to their usage of RMRRs that are known
> +	 * to not be needed after BIOS hand-off to OS.
> +	 */
> +	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;
>  



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