Re: [PATCH] iommu/amd: flush IOTLB for specific domains only (v2)

[Michel Dänzer]

On 22/05/17 10:08 AM, Michel Dänzer wrote:
> On 19/05/17 07:02 PM, arindam.n...@amd.com wrote:
>> From: Arindam Nath 
>>
>> Change History
>> --
>>
>> v2: changes suggested by Joerg
>> - add flush flag to improve efficiency of flush operation
>>
>> v1:
>> - The idea behind flush queues is to defer the IOTLB flushing
>>   for domains for which the mappings are no longer valid. We
>>   add such domains in queue_add(), and when the queue size
>>   reaches FLUSH_QUEUE_SIZE, we perform __queue_flush().
>>
>>   Since we have already taken lock before __queue_flush()
>>   is called, we need to make sure the IOTLB flushing is
>>   performed as quickly as possible.
>>
>>   In the current implementation, we perform IOTLB flushing
>>   for all domains irrespective of which ones were actually
>>   added in the flush queue initially. This can be quite
>>   expensive especially for domains for which unmapping is
>>   not required at this point of time.
>>
>>   This patch makes use of domain information in
>>   'struct flush_queue_entry' to make sure we only flush
>>   IOTLBs for domains who need it, skipping others.
>>
>> Suggested-by: Joerg Roedel 
>> Signed-off-by: Arindam Nath 
> 
> Please add these tags:
> 
> Fixes: b1516a14657a ("iommu/amd: Implement flush queue")
> Cc: sta...@vger.kernel.org

Also

Bugzilla: https://bugs.freedesktop.org/101029


-- 
Earthling Michel Dänzer   |   http://www.amd.com
Libre software enthusiast | Mesa and X developer
___
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

Re: [PATCH] iommu/amd: flush IOTLB for specific domains only (v2)

[Michel Dänzer]

On 19/05/17 07:02 PM, arindam.n...@amd.com wrote:
> From: Arindam Nath 
> 
> Change History
> --
> 
> v2: changes suggested by Joerg
> - add flush flag to improve efficiency of flush operation
> 
> v1:
> - The idea behind flush queues is to defer the IOTLB flushing
>   for domains for which the mappings are no longer valid. We
>   add such domains in queue_add(), and when the queue size
>   reaches FLUSH_QUEUE_SIZE, we perform __queue_flush().
> 
>   Since we have already taken lock before __queue_flush()
>   is called, we need to make sure the IOTLB flushing is
>   performed as quickly as possible.
> 
>   In the current implementation, we perform IOTLB flushing
>   for all domains irrespective of which ones were actually
>   added in the flush queue initially. This can be quite
>   expensive especially for domains for which unmapping is
>   not required at this point of time.
> 
>   This patch makes use of domain information in
>   'struct flush_queue_entry' to make sure we only flush
>   IOTLBs for domains who need it, skipping others.
> 
> Suggested-by: Joerg Roedel 
> Signed-off-by: Arindam Nath 

Please add these tags:

Fixes: b1516a14657a ("iommu/amd: Implement flush queue")
Cc: sta...@vger.kernel.org


-- 
Earthling Michel Dänzer   |   http://www.amd.com
Libre software enthusiast | Mesa and X developer
___
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

RE: [PATCH] iommu/amd: flush IOTLB for specific domains only (v2)

[Nath, Arindam]

>-Original Message-
>From: Jan Vesely [mailto:jv...@scarletmail.rutgers.edu] On Behalf Of Jan
>Vesely
>Sent: Friday, May 19, 2017 7:06 PM
>To: Nath, Arindam; io...@lists.linux-foundation.org
>Cc: Bridgman, John; Joerg Roedel; amd-gfx@lists.freedesktop.org;
>dr...@endlessm.com; Craig Stein; Suthikulpanit, Suravee; Deucher,
>Alexander; Kuehling, Felix; li...@endlessm.com; mic...@daenzer.net
>Subject: Re: [PATCH] iommu/amd: flush IOTLB for specific domains only (v2)
>
>On Fri, 2017-05-19 at 15:32 +0530, arindam.n...@amd.com wrote:
>> From: Arindam Nath <arindam.n...@amd.com>
>>
>> Change History
>> --
>>
>> v2: changes suggested by Joerg
>> - add flush flag to improve efficiency of flush operation

Joerg, do you have any comments on the patch?

Thanks,
Arindam

>>
>> v1:
>> - The idea behind flush queues is to defer the IOTLB flushing
>>   for domains for which the mappings are no longer valid. We
>>   add such domains in queue_add(), and when the queue size
>>   reaches FLUSH_QUEUE_SIZE, we perform __queue_flush().
>>
>>   Since we have already taken lock before __queue_flush()
>>   is called, we need to make sure the IOTLB flushing is
>>   performed as quickly as possible.
>>
>>   In the current implementation, we perform IOTLB flushing
>>   for all domains irrespective of which ones were actually
>>   added in the flush queue initially. This can be quite
>>   expensive especially for domains for which unmapping is
>>   not required at this point of time.
>>
>>   This patch makes use of domain information in
>>   'struct flush_queue_entry' to make sure we only flush
>>   IOTLBs for domains who need it, skipping others.
>
>Hi,
>
>just a note, the patch also fixes "AMD-Vi: Completion-Wait loop timed
>out" boot hang on my system (carrizo + iceland) [0,1,2]. Presumably the
>old loop also tried to flush domains that included powered-off devices.
>
>regards,
>Jan
>
>[0] https://github.com/RadeonOpenCompute/ROCK-Kernel-Driver/issues/20
>[1] https://bugs.freedesktop.org/show_bug.cgi?id=101029
>[2] https://bugzilla.redhat.com/show_bug.cgi?id=1448121
>
>>
>> Suggested-by: Joerg Roedel <j...@8bytes.org>
>> Signed-off-by: Arindam Nath <arindam.n...@amd.com>
>> ---
>>  drivers/iommu/amd_iommu.c   | 27 ---
>>  drivers/iommu/amd_iommu_types.h |  2 ++
>>  2 files changed, 22 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
>> index 63cacf5..1edeebec 100644
>> --- a/drivers/iommu/amd_iommu.c
>> +++ b/drivers/iommu/amd_iommu.c
>> @@ -2227,15 +2227,26 @@ static struct iommu_group
>*amd_iommu_device_group(struct device *dev)
>>
>>  static void __queue_flush(struct flush_queue *queue)
>>  {
>> -struct protection_domain *domain;
>> -unsigned long flags;
>>  int idx;
>>
>> -/* First flush TLB of all known domains */
>> -spin_lock_irqsave(_iommu_pd_lock, flags);
>> -list_for_each_entry(domain, _iommu_pd_list, list)
>> -domain_flush_tlb(domain);
>> -spin_unlock_irqrestore(_iommu_pd_lock, flags);
>> +/* First flush TLB of all domains which were added to flush queue */
>> +for (idx = 0; idx < queue->next; ++idx) {
>> +struct flush_queue_entry *entry;
>> +
>> +entry = queue->entries + idx;
>> +
>> +/*
>> + * There might be cases where multiple IOVA entries for the
>> + * same domain are queued in the flush queue. To avoid
>> + * flushing the same domain again, we check whether the
>> + * flag is set or not. This improves the efficiency of
>> + * flush operation.
>> + */
>> +if (!entry->dma_dom->domain.already_flushed) {
>> +entry->dma_dom->domain.already_flushed = true;
>> +domain_flush_tlb(>dma_dom->domain);
>> +}
>> +}
>>
>>  /* Wait until flushes have completed */
>>  domain_flush_complete(NULL);
>> @@ -2289,6 +2300,8 @@ static void queue_add(struct dma_ops_domain
>*dma_dom,
>>  pages = __roundup_pow_of_two(pages);
>>  address >>= PAGE_SHIFT;
>>
>> +dma_dom->domain.already_flushed = false;
>> +
>>  queue = get_cpu_ptr(_queue);
>>  spin_lock_irqsave(>lock, flags);
>>
>> diff --git a/drivers/iommu/amd

Re: [PATCH] iommu/amd: flush IOTLB for specific domains only (v2)

[Jan Vesely]

On Fri, 2017-05-19 at 15:32 +0530, arindam.n...@amd.com wrote:
> From: Arindam Nath 
> 
> Change History
> --
> 
> v2: changes suggested by Joerg
> - add flush flag to improve efficiency of flush operation
> 
> v1:
> - The idea behind flush queues is to defer the IOTLB flushing
>   for domains for which the mappings are no longer valid. We
>   add such domains in queue_add(), and when the queue size
>   reaches FLUSH_QUEUE_SIZE, we perform __queue_flush().
> 
>   Since we have already taken lock before __queue_flush()
>   is called, we need to make sure the IOTLB flushing is
>   performed as quickly as possible.
> 
>   In the current implementation, we perform IOTLB flushing
>   for all domains irrespective of which ones were actually
>   added in the flush queue initially. This can be quite
>   expensive especially for domains for which unmapping is
>   not required at this point of time.
> 
>   This patch makes use of domain information in
>   'struct flush_queue_entry' to make sure we only flush
>   IOTLBs for domains who need it, skipping others.

Hi,

just a note, the patch also fixes "AMD-Vi: Completion-Wait loop timed
out" boot hang on my system (carrizo + iceland) [0,1,2]. Presumably the
old loop also tried to flush domains that included powered-off devices.

regards,
Jan

[0] https://github.com/RadeonOpenCompute/ROCK-Kernel-Driver/issues/20
[1] https://bugs.freedesktop.org/show_bug.cgi?id=101029
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1448121

> 
> Suggested-by: Joerg Roedel 
> Signed-off-by: Arindam Nath 
> ---
>  drivers/iommu/amd_iommu.c   | 27 ---
>  drivers/iommu/amd_iommu_types.h |  2 ++
>  2 files changed, 22 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index 63cacf5..1edeebec 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -2227,15 +2227,26 @@ static struct iommu_group 
> *amd_iommu_device_group(struct device *dev)
>  
>  static void __queue_flush(struct flush_queue *queue)
>  {
> - struct protection_domain *domain;
> - unsigned long flags;
>   int idx;
>  
> - /* First flush TLB of all known domains */
> - spin_lock_irqsave(_iommu_pd_lock, flags);
> - list_for_each_entry(domain, _iommu_pd_list, list)
> - domain_flush_tlb(domain);
> - spin_unlock_irqrestore(_iommu_pd_lock, flags);
> + /* First flush TLB of all domains which were added to flush queue */
> + for (idx = 0; idx < queue->next; ++idx) {
> + struct flush_queue_entry *entry;
> +
> + entry = queue->entries + idx;
> +
> + /*
> +  * There might be cases where multiple IOVA entries for the
> +  * same domain are queued in the flush queue. To avoid
> +  * flushing the same domain again, we check whether the
> +  * flag is set or not. This improves the efficiency of
> +  * flush operation.
> +  */
> + if (!entry->dma_dom->domain.already_flushed) {
> + entry->dma_dom->domain.already_flushed = true;
> + domain_flush_tlb(>dma_dom->domain);
> + }
> + }
>  
>   /* Wait until flushes have completed */
>   domain_flush_complete(NULL);
> @@ -2289,6 +2300,8 @@ static void queue_add(struct dma_ops_domain *dma_dom,
>   pages = __roundup_pow_of_two(pages);
>   address >>= PAGE_SHIFT;
>  
> + dma_dom->domain.already_flushed = false;
> +
>   queue = get_cpu_ptr(_queue);
>   spin_lock_irqsave(>lock, flags);
>  
> diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
> index 4de8f41..4f5519d 100644
> --- a/drivers/iommu/amd_iommu_types.h
> +++ b/drivers/iommu/amd_iommu_types.h
> @@ -454,6 +454,8 @@ struct protection_domain {
>   bool updated;   /* complete domain flush required */
>   unsigned dev_cnt;   /* devices assigned to this domain */
>   unsigned dev_iommu[MAX_IOMMUS]; /* per-IOMMU reference count */
> + bool already_flushed;   /* flag to avoid flushing the same domain again
> +in a single invocation of __queue_flush() */
>  };
>  
>  /*

-- 
Jan Vesely 

signature.asc
Description: This is a digitally signed message part
___
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx