Re: [Xen-devel] [PATCH v6 08/10] remove late (on-demand) construction of IOMMU page tables

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 8/16/19 8:19 PM, Paul Durrant wrote:
> Now that there is a per-domain IOMMU enable flag, which should be enabled if
> any device is going to be passed through, stop deferring page table
> construction until the assignment is done. Also don't tear down the tables
> again when the last device is de-assigned; defer that task until domain
> destruction.
> 
> This allows the has_iommu_pt() helper and iommu_status enumeration to be
> removed. Calls to has_iommu_pt() are simply replaced by calls to
> is_iommu_enabled(). Remaining open-code tests of iommu_hap_pt_share can also
> be replaced by calls to iommu_use_hap_pt().
> The arch_iommu_populate_page_table() and iommu_construct() functions become
> redundant, as does the 'strict mode' dom0 page_list mapping code in
> iommu_hwdom_init(), and iommu_teardown() can be made static is its only
> remaining caller, iommu_domain_destroy(), is within the same source
> module.
> 
> All in all, about 220 lines of code are removed.
> 
> NOTE: This patch will cause a small amount of extra resource to be used
>       to accommodate IOMMU page tables that may never be used, since the
>       per-domain IOMMU flag enable flag is currently set to the value
>       of the global iommu_enable flag. A subsequent patch will add an
>       option to the toolstack to allow it to be turned off if there is
>       no intention to assign passthrough hardware to the domain.

This has slipped under my radar, sorry.

Acked-by: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>


Thanks,
Razvan

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