linux-kernel - Re: [PATCH 2/6] iommu/vt-d: move up no_iommu and dmar

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Message-ID: <53B673CF.2040101@huawei.com>
Date:	Fri, 4 Jul 2014 17:28:47 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Joerg Roedel <joro@...tes.org>
CC:	David Woodhouse <dwmw2@...radead.org>,
	<iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] iommu/vt-d: move up no_iommu and dmar_disabled check

>> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
>> index e020dcf..6b71608 100644
>> --- a/drivers/iommu/intel-iommu.c
>> +++ b/drivers/iommu/intel-iommu.c
>> @@ -3948,6 +3948,9 @@ int __init intel_iommu_init(void)
>>  	/* VT-d is required for a TXT/tboot launch, so enforce that */
>>  	force_on = tboot_force_iommu();
>>  
>> +	if (no_iommu || dmar_disabled)
>> +		return ret;
>> +
>>  	if (iommu_init_mempool()) {
>>  		if (force_on)
>>  			panic("tboot: Failed to initialize iommu memory\n");
>> @@ -3974,9 +3977,6 @@ int __init intel_iommu_init(void)
>>  		goto out_free_dmar;
>>  	}
>>  
>> -	if (no_iommu || dmar_disabled)
>> -		goto out_free_dmar;
>> -
>>  	if (list_empty(&dmar_rmrr_units))
>>  		printk(KERN_INFO "DMAR: No RMRR found\n");
> 
> This breaks the kexec case were the old kernel had VT-d enabled and the
> new one disabled. In this case the new kernel might need to disable the
> IOMMUs.

Hi Joerg,
   Thanks for your review and comments! You are right, I didn't consider the kexec case,
I will drop this patch.

Thanks!
Yijing.


> 
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-- 
Thanks!
Yijing

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