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

Yi Sun
2021-02-07T10:04:04Z

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