Re: [RFC PATCH 10/11] vfio/iommu_type1: Optimize dirty bitmap population based on iommu HWDBM

[Yi Sun]

Hi,

On 21-01-28 23:17:41, Keqian Zhu wrote:

[...]

> +static void vfio_dma_dirty_log_start(struct vfio_iommu *iommu,
> +				     struct vfio_dma *dma)
> +{
> +	struct vfio_domain *d;
> +
> +	list_for_each_entry(d, &iommu->domain_list, next) {
> +		/* Go through all domain anyway even if we fail */
> +		iommu_split_block(d->domain, dma->iova, dma->size);
> +	}
> +}

This should be a switch to prepare for dirty log start. Per Intel
Vtd spec, there is SLADE defined in Scalable-Mode PASID Table Entry.
It enables Accessed/Dirty Flags in second-level paging entries.
So, a generic iommu interface here is better. For Intel iommu, it
enables SLADE. For ARM, it splits block.

> +
> +static void vfio_dma_dirty_log_stop(struct vfio_iommu *iommu,
> +				    struct vfio_dma *dma)
> +{
> +	struct vfio_domain *d;
> +
> +	list_for_each_entry(d, &iommu->domain_list, next) {
> +		/* Go through all domain anyway even if we fail */
> +		iommu_merge_page(d->domain, dma->iova, dma->size,
> +				 d->prot | dma->prot);
> +	}
> +}

Same as above comment, a generic interface is required here.

> +
> +static void vfio_iommu_dirty_log_switch(struct vfio_iommu *iommu, bool start)
> +{
> +	struct rb_node *n;
> +
> +	/* Split and merge even if all iommu don't support HWDBM now */
> +	for (n = rb_first(&iommu->dma_list); n; n = rb_next(n)) {
> +		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
> +
> +		if (!dma->iommu_mapped)
> +			continue;
> +
> +		/* Go through all dma range anyway even if we fail */
> +		if (start)
> +			vfio_dma_dirty_log_start(iommu, dma);
> +		else
> +			vfio_dma_dirty_log_stop(iommu, dma);
> +	}
> +}
> +
>  static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
>  					unsigned long arg)
>  {
> @@ -2812,8 +2900,10 @@ static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
>  		pgsize = 1 << __ffs(iommu->pgsize_bitmap);
>  		if (!iommu->dirty_page_tracking) {
>  			ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
> -			if (!ret)
> +			if (!ret) {
>  				iommu->dirty_page_tracking = true;
> +				vfio_iommu_dirty_log_switch(iommu, true);
> +			}
>  		}
>  		mutex_unlock(&iommu->lock);
>  		return ret;
> @@ -2822,6 +2912,7 @@ static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
>  		if (iommu->dirty_page_tracking) {
>  			iommu->dirty_page_tracking = false;
>  			vfio_dma_bitmap_free_all(iommu);
> +			vfio_iommu_dirty_log_switch(iommu, false);
>  		}
>  		mutex_unlock(&iommu->lock);
>  		return 0;
> -- 
> 2.19.1