On 2021/1/16 7:30, Alex Williamson wrote:
> On Thu, 7 Jan 2021 12:43:58 +0800
> Keqian Zhu <zhukeqi...@huawei.com> wrote:
>
>> For now there are 3 ways to promote the pinned_page_dirty_scope
>> status of vfio_iommu:
>>
>> 1. Through vfio pin interface.
>> 2. Detach a group without pinned_dirty_scope.
>> 3. Attach a group with pinned_dirty_scope.
>>
>> For point 3, the only chance to promote the pinned_page_dirty_scope
>> status is when vfio_iommu is newly created. As we can safely set
>> empty vfio_iommu to be at pinned status, then the point 3 can be
>> removed to reduce operations.
>>
>> Signed-off-by: Keqian Zhu <zhukeqi...@huawei.com>
>> ---
>> drivers/vfio/vfio_iommu_type1.c | 4 +---
>> 1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/vfio/vfio_iommu_type1.c
>> b/drivers/vfio/vfio_iommu_type1.c
>> index 110ada24ee91..b596c482487b 100644
>> --- a/drivers/vfio/vfio_iommu_type1.c
>> +++ b/drivers/vfio/vfio_iommu_type1.c
>> @@ -2045,11 +2045,8 @@ static int vfio_iommu_type1_attach_group(void
>> *iommu_data,
>> * Non-iommu backed group cannot dirty memory directly,
>> * it can only use interfaces that provide dirty
>> * tracking.
>> - * The iommu scope can only be promoted with the
>> - * addition of a dirty tracking group.
>> */
>> group->pinned_page_dirty_scope = true;
>> - promote_pinned_page_dirty_scope(iommu);
>> mutex_unlock(&iommu->lock);
>>
>> return 0;
>> @@ -2436,6 +2433,7 @@ static void *vfio_iommu_type1_open(unsigned long arg)
>> INIT_LIST_HEAD(&iommu->iova_list);
>> iommu->dma_list = RB_ROOT;
>> iommu->dma_avail = dma_entry_limit;
>> + iommu->pinned_page_dirty_scope = true;
>> mutex_init(&iommu->lock);
>> BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier);
>>
>
> This would be resolved automatically if we used the counter approach I
> mentioned on the previous patch, adding a pinned-page scope group simply
> wouldn't increment the iommu counter, which would initially be zero
> indicating no "all-dma" groups. Thanks,
>
Sure, I will do that, thanks.
Keqian.
> Alex
>
> .
>
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