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

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Message-ID: <9774516974AF5F4C8A2C3C69CD341233233C1A44@G1W3651.americas.hpqcorp.net>
Date:	Tue, 16 Oct 2012 17:41:11 +0000
From:	"Mingarelli, Thomas" <Thomas.Mingarelli@...com>
To:	"Khan, Shuah" <shuah.khan@...com>
CC:	Alex Williamson <alex.williamson@...hat.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Don Dutile <ddutile@...hat.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>,
	"shuahkhan@...il.com" <shuahkhan@...il.com>
Subject: RE: [PATCH v3] Prevent devices with RMRRs from being placed into SI
 Domain during startup

I imagine there could be other devices that get a "free ride". Any help or suggestions in that area are greatly appreciated.


Tom

-----Original Message-----
From: Khan, Shuah 
Sent: Tuesday, October 16, 2012 12:28 PM
To: Mingarelli, Thomas
Cc: Alex Williamson; David Woodhouse; Don Dutile; Knippers, Linda; iommu@...ts.linux-foundation.org; linux-kernel@...r.kernel.org; shuahkhan@...il.com
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. We don't need a separate bit
> +		 * for this because it could be ANY device.
> +		*/
> +		if (device_has_rmrr(pdev) &&
> +			(pdev->class >> 8) != PCI_CLASS_SERIAL_USB)

Forgot to ask in my last response. Is it sufficient to check _USB. Are
we missing any other devices that use RMRR that would qualify?

> +				return 0;
> +	}
> +
>  	if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
>  		return 1;
>