lkml.org 
[lkml]   [2023]   [Sep]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 1/2] iommu/virtio: Make use of ops->iotlb_sync_map
From
On 22/09/2023 1:41 pm, Jason Gunthorpe wrote:
> On Fri, Sep 22, 2023 at 08:57:19AM +0100, Jean-Philippe Brucker wrote:
>>>> They're not strictly equivalent: this check works around a temporary issue
>>>> with the IOMMU core, which calls map/unmap before the domain is
>>>> finalized.
>>>
>>> Where? The above points to iommu_create_device_direct_mappings() but
>>> it doesn't because the pgsize_bitmap == 0:
>>
>> __iommu_domain_alloc() sets pgsize_bitmap in this case:
>>
>> /*
>> * If not already set, assume all sizes by default; the driver
>> * may override this later
>> */
>> if (!domain->pgsize_bitmap)
>> domain->pgsize_bitmap = bus->iommu_ops->pgsize_bitmap;
>
> Dirver's shouldn't do that.
>
> The core code was fixed to try again with mapping reserved regions to
> support these kinds of drivers.

This is still the "normal" code path, really; I think it's only AMD that
started initialising the domain bitmap "early" and warranted making it
conditional. However we *do* ultimately want all the drivers to do the
same, so we can get rid of ops->pgsize_bitmap, because it's already
pretty redundant and meaningless in the face of per-domain pagetable
formats.

Thanks,
Robin.

\
 
 \ /
  Last update: 2023-09-22 16:27    [W:0.076 / U:2.768 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site