linux-kernel - Re: [PATCH v7 10/10] iommu/arm-smmu: call iommu_free_reserved_iova

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Date:	Thu, 21 Apr 2016 10:39:30 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	Robin Murphy <robin.murphy@....com>, eric.auger@...com,
	alex.williamson@...hat.com, will.deacon@....com, joro@...tes.org,
	tglx@...utronix.de, jason@...edaemon.net, marc.zyngier@....com,
	christoffer.dall@...aro.org, linux-arm-kernel@...ts.infradead.org
Cc:	patches@...aro.org, linux-kernel@...r.kernel.org,
	Bharat.Bhushan@...escale.com, pranav.sawargaonkar@...il.com,
	p.fedin@...sung.com, iommu@...ts.linux-foundation.org,
	Jean-Philippe.Brucker@....com, julien.grall@....com
Subject: Re: [PATCH v7 10/10] iommu/arm-smmu: call
 iommu_free_reserved_iova_domain on domain destruction

Hi Robin,
On 04/20/2016 07:35 PM, Robin Murphy wrote:
> On 19/04/16 17:56, Eric Auger wrote:
>> When the domain gets destroyed, let's make sure all reserved iova
>> resources get released.
>>
>> Choice is made to put that call in arm-smmu(-v3).c to do something
>> similar
>> to what was done for iommu_put_dma_cookie.
>>
>> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>>
>> ---
>>
>> v7: new
>> ---
>>   drivers/iommu/arm-smmu-v3.c | 2 ++
>>   drivers/iommu/arm-smmu.c    | 2 ++
>>   2 files changed, 4 insertions(+)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index a077a35..afd0dac 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -22,6 +22,7 @@
>>
>>   #include <linux/delay.h>
>>   #include <linux/dma-iommu.h>
>> +#include <linux/dma-reserved-iommu.h>
>>   #include <linux/err.h>
>>   #include <linux/interrupt.h>
>>   #include <linux/iommu.h>
>> @@ -1444,6 +1445,7 @@ static void arm_smmu_domain_free(struct
>> iommu_domain *domain)
>>       struct arm_smmu_device *smmu = smmu_domain->smmu;
>>
>>       iommu_put_dma_cookie(domain);
>> +    iommu_free_reserved_iova_domain(domain);
> 
> Yikes! No, drivers shouldn't be randomly freeing things they didn't
> allocate - the owner of the domain, who presumably allocated the thing,
> can call that right _before_ they call iommu_domain_free().
OK I move that back to vfio_iommu_type1.c.

Thanks

Eric
> 
>>       free_io_pgtable_ops(smmu_domain->pgtbl_ops);
>>
>>       /* Free the CD and ASID, if we allocated them */
>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
>> index 8cd7b8a..492339f 100644
>> --- a/drivers/iommu/arm-smmu.c
>> +++ b/drivers/iommu/arm-smmu.c
>> @@ -30,6 +30,7 @@
>>
>>   #include <linux/delay.h>
>>   #include <linux/dma-iommu.h>
>> +#include <linux/dma-reserved-iommu.h>
>>   #include <linux/dma-mapping.h>
>>   #include <linux/err.h>
>>   #include <linux/interrupt.h>
>> @@ -1009,6 +1010,7 @@ static void arm_smmu_domain_free(struct
>> iommu_domain *domain)
>>        * already been detached.
>>        */
>>       iommu_put_dma_cookie(domain);
>> +    iommu_free_reserved_iova_domain(domain);
> 
> ...which has the added bonus of preventing needless duplication everywhere.
> 
> Robin.
> 
>>       arm_smmu_destroy_domain_context(domain);
>>       kfree(smmu_domain);
>>   }
>>
>