Re: [Xen-devel] [PATCH v3 04/14] AMD/IOMMU: use bit field for IRTE

[Jan Beulich <JBeulich@xxxxxxxx>]

On 19.07.2019 17:56, Andrew Cooper wrote:
> On 16/07/2019 17:36, Jan Beulich wrote:
>> At the same time restrict its scope to just the single source file
>> actually using it, and abstract accesses by introducing a union of
>> pointers. (A union of the actual table entries is not used to make it
>> impossible to [wrongly, once the 128-bit form gets added] perform
>> pointer arithmetic / array accesses on derived types.)
>>
>> Also move away from updating the entries piecemeal: Construct a full new
>> entry, and write it out.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> I'm still not entirely convinced by extra union and containerof(), but
> the result looks correct.

And I'm still open to going the other way, if you're convinced that
in update_intremap_entry() this

     struct irte_basic basic = {
         .flds = {
             .remap_en = true,
             .int_type = int_type,
             .dm = dest_mode,
             .dest = dest,
             .vector = vector,
         }
     };

(and similarly then for the 128-bit form, and of course .flds
inserted at other use sites) is overall better than the current
variant.

> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks, Jan

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