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Date: Tue, 20 Nov 2007 10:58:22 -0800
From: mark gross <mgross@linux.intel.com>
To: Fenghua Yu <fenghua.yu@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       lkml <linux-kernel@vger.kernel.org>, torvalds@linux-foundation.org
Subject: Re: [PATCH] More Sanity checks for DMAR
Message-ID: <20071120185822.GA25785@linux.intel.com>
Reply-To: mgross@linux.intel.com
References: <BAE9DCEF64577A439B3A37F36F9B691C0339372B@orsmsx418.amr.corp.intel.com> <20071119230348.GA18775@linux-os.sc.intel.com>
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On Mon, Nov 19, 2007 at 03:03:48PM -0800, Fenghua Yu wrote:
> 
> This patch adds and changes a few sanity checks in dmar.c.
> 
> 1. The haw field in ACPI DMAR table in VT-d spec doesn't describe the range of
> haw. But since DMA page size is 4KB in DMA remapping, haw should be at least
> 4KB. The current VT-d code in dmar.c returns failure when haw==0. This sanity
> check is not accurate and execution can pass when haw is less than one page
> size 4KB. This patch changes the haw sanity check to validate if haw is less
> than 4KB.
> 2. Add dmar_rmrr_units verification.
> 3. Add parse_dmar_table() verification.
> 
> Thanks.
> 
> -Fenghua
> 
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> 
> ---
> 
>  dmar.c |   20 +++++++++++++++++---
>  1 files changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c
> index 5dfdfda..a5b6ed0 100644
> --- a/drivers/pci/dmar.c
> +++ b/drivers/pci/dmar.c
> @@ -25,6 +25,7 @@
>  
>  #include <linux/pci.h>
>  #include <linux/dmar.h>
> +#include "iova.h"
>  
>  #undef PREFIX
>  #define PREFIX "DMAR:"
> @@ -263,8 +264,8 @@ parse_dmar_table(void)
>  	if (!dmar)
>  		return -ENODEV;
>  
> -	if (!dmar->width) {
> -		printk (KERN_WARNING PREFIX "Zero: Invalid DMAR haw\n");
> +	if (dmar->width < PAGE_SHIFT_4K - 1) {
> +		printk (KERN_WARNING PREFIX "Invalid DMAR haw\n");
>  		return -EINVAL;
>  	}
>  
> @@ -301,11 +302,24 @@ parse_dmar_table(void)
>  int __init dmar_table_init(void)
>  {
>  
> -	parse_dmar_table();
> +	int ret;
> +	
> +	ret = parse_dmar_table();
> +	if (ret) {
> +		printk(KERN_INFO PREFIX "parse DMAR table failure.\n");
> +		return ret;
> +	}
> +
>  	if (list_empty(&dmar_drhd_units)) {
>  		printk(KERN_INFO PREFIX "No DMAR devices found\n");
>  		return -ENODEV;
>  	}
> +
> +	if (list_empty(&dmar_rmrr_units)) {
> +		printk(KERN_INFO PREFIX "No RMRR found\n");
> +		return -ENODEV;
> +	}
> +
>  	return 0;
>  }
>  
> -
Ack : mark gross <mgross@linux.intel.com>

Thanks,

--mgross