On 30.01.2025 21:17, Jason Andryuk wrote:
> On 2025-01-21 11:13, Teddy Astie wrote:
>> +/**
>> + * IOMMU_alloc_nested
>> + * Create a nested IOMMU context (needs IOMMUCAP_nested).
>> + *
>> + * This context uses a platform-specific page table from domain address
>> space
>> + * specified in pgtable_gfn and use it for nested translations.
>> + *
>> + * Explicit flushes needs to be submited with IOMMU_flush_nested on
>> + * modification of the nested pagetable to ensure coherency between IOTLB
>> and
>> + * nested page table.
>> + *
>> + * This context can be destroyed using IOMMU_free_context.
>> + * This context cannot be modified using map_pages, unmap_pages.
>> + */
>> +struct pv_iommu_alloc_nested {
>> + /* OUT: allocated IOMMU context number */
>> + uint16_t ctx_no;
>> +
>> + /* IN: guest frame number of the nested page table */
>> + uint64_aligned_t pgtable_gfn;
>> +
>> + /* IN: nested mode flags */
>> + uint64_aligned_t nested_flags;
>> +};
>> +typedef struct pv_iommu_alloc_nested pv_iommu_alloc_nested_t;
>> +DEFINE_XEN_GUEST_HANDLE(pv_iommu_alloc_nested_t);
>
> Is this command intended to be used for GVA -> GPA translation? Would you
> need some way to associate with another iommu context for GPA -> HPA
> translation?
>
> Maybe more broadly, what are your goals for enabling PV-IOMMU? The examples
> on your blog post cover a domain restrict device access to specific portions
> of the the GPA space. Are you also interested in GVA -> GPA? Does VFIO
> required GVA -> GPA?
>
> And, sorry to bike shed, but ctx_no reads like "Context No" to me. I think
> ctxid/ctx_id might be clearer. Others probably have their own opinions :)
Or, if it absolutely is to derive from "number", ctx_nr. That said, I
agree "id" is a better term to use here.
Jan
