linux-kernel - Re: amd_iommu_init.c: possible problem with IVHD_FLAG_HT_TUN

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Message-ID: <20090504081345.GD6780@amd.com>
Date:	Mon, 4 May 2009 10:13:46 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Julia Lawall <julia@...u.dk>
CC:	iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: amd_iommu_init.c: possible problem with IVHD_FLAG_HT_TUN_EN

On Sat, May 02, 2009 at 03:20:23PM +0200, Julia Lawall wrote:
> The file arch/x86/kernel/amd_iommu_init.c contains the following code:
> 
> (starting at line 586 in a recent linux-next)
> 
> 	h->flags & IVHD_FLAG_HT_TUN_EN ?
> 		iommu_feature_enable(iommu, CONTROL_HT_TUN_EN) :
> 		iommu_feature_disable(iommu, CONTROL_HT_TUN_EN);
> 
> 	h->flags & IVHD_FLAG_PASSPW_EN ?
> 		iommu_feature_enable(iommu, CONTROL_PASSPW_EN) :
> 		iommu_feature_disable(iommu, CONTROL_PASSPW_EN);
> 
> 	h->flags & IVHD_FLAG_RESPASSPW_EN ?
> 		iommu_feature_enable(iommu, CONTROL_RESPASSPW_EN) :
> 		iommu_feature_disable(iommu, CONTROL_RESPASSPW_EN);
> 
> 	h->flags & IVHD_FLAG_ISOC_EN ?
> 		iommu_feature_enable(iommu, CONTROL_ISOC_EN) :
> 		iommu_feature_disable(iommu, CONTROL_ISOC_EN);
> 
> The only possible value of IVHD_FLAG_HT_TUN_EN, however, seems to be 0, as
> defined in the same file, and thus the first test is never true.  Is this
> what is intended, or should the test be expressed in another way?

Very true. Another bug because I mixed up bit shifts with bit masks :-(
Thanks for reporting this. I will send a patch to fix it.

Joerg

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