RE: [PATCH v4 03/14] x86/iommu: convert VT-d code to use new page table allocator

["Durrant, Paul" <pdurrant@amazon.co.uk>]

> -----Original Message-----
[snip]
> > -static void iommu_free_page_table(struct page_info *pg)
> > -{
> > -    unsigned int i, next_level = PFN_ORDER(pg) - 1;
> > -    u64 pt_maddr = page_to_maddr(pg);
> > -    struct dma_pte *pt_vaddr, *pte;
> > -
> > -    PFN_ORDER(pg) = 0;
> > -    pt_vaddr = (struct dma_pte *)map_vtd_domain_page(pt_maddr);
> > -
> > -    for ( i = 0; i < PTE_NUM; i++ )
> > -    {
> > -        pte = &pt_vaddr[i];
> > -        if ( !dma_pte_present(*pte) )
> > -            continue;
> > -
> > -        if ( next_level >= 1 )
> > -            iommu_free_pagetable(dma_pte_addr(*pte), next_level);
> > -
> > -        dma_clear_pte(*pte);
> > -        iommu_sync_cache(pte, sizeof(struct dma_pte));
> 
> I didn't see sync_cache in the new iommu_free_pgtables. Is it intended
> (i.e. original flush is meaningless) or overlooked?
> 

The original v1 combined patch had the comment:

NOTE: There is no need to clear and sync PTEs during teardown since the per-
      device root entries will have already been cleared (when devices were
      de-assigned) so the page tables can no longer be accessed by the IOMMU.

I should have included that note in this one. I'll fix in v5.

  Paul

> Thanks
> Kevin