Re: [PATCH 15/17] IOMMU: page table dumping adjustments

[Jan Beulich <jbeulich@xxxxxxxx>]

On 24.08.2021 16:26, Jan Beulich wrote:
> For one none of the three IOMMU implementations on Arm specify a dumping
> hook. Generalize VT-d's "don't dump shared page tables" to cover for
> this.
> 
> Further in the past I was told that on Arm in principle there could be
> multiple different IOMMUs, and hence different domains' platform_ops
> pointers could differ. Use each domain's ops for calling the dump hook.
> (In the long run all uses of iommu_get_ops() would likely need to
> disappear for this reason.)
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Should have Cc-ed Kevin on this one as well; now added.

Jan

> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -640,12 +640,9 @@ bool_t iommu_has_feature(struct domain *
>  static void iommu_dump_page_tables(unsigned char key)
>  {
>      struct domain *d;
> -    const struct iommu_ops *ops;
>  
>      ASSERT(iommu_enabled);
>  
> -    ops = iommu_get_ops();
> -
>      rcu_read_lock(&domlist_read_lock);
>  
>      for_each_domain(d)
> @@ -653,7 +650,13 @@ static void iommu_dump_page_tables(unsig
>          if ( is_hardware_domain(d) || !is_iommu_enabled(d) )
>              continue;
>  
> -        ops->dump_page_tables(d);
> +        if ( iommu_use_hap_pt(d) )
> +        {
> +            printk("%pd sharing page tables\n", d);
> +            continue;
> +        }
> +
> +        dom_iommu(d)->platform_ops->dump_page_tables(d);
>      }
>  
>      rcu_read_unlock(&domlist_read_lock);
> --- a/xen/drivers/passthrough/vtd/iommu.c
> +++ b/xen/drivers/passthrough/vtd/iommu.c
> @@ -2835,12 +2835,6 @@ static void vtd_dump_page_tables(struct
>  {
>      const struct domain_iommu *hd = dom_iommu(d);
>  
> -    if ( iommu_use_hap_pt(d) )
> -    {
> -        printk(VTDPREFIX " %pd sharing EPT table\n", d);
> -        return;
> -    }
> -
>      printk(VTDPREFIX" %pd table has %d levels\n", d,
>             agaw_to_level(hd->arch.vtd.agaw));
>      vtd_dump_page_table_level(hd->arch.vtd.pgd_maddr,
> 
>