Messages in this thread | | | Subject | Re: [PATCH v2 3/4] drm/ttm, drm/vmwgfx: Correctly support support AMD memory encryption | From | Thomas Hellström (VMware) <> | Date | Wed, 4 Sep 2019 12:37:45 +0200 |
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On 9/4/19 9:53 AM, Daniel Vetter wrote: > On Wed, Sep 4, 2019 at 8:49 AM Thomas Hellström (VMware) > <thomas_os@shipmail.org> wrote: >> On 9/4/19 1:15 AM, Andy Lutomirski wrote: >>> But, reading this, I have more questions: >>> >>> Can’t you get rid of cvma by using vmf_insert_pfn_prot()? >> It looks like that, although there are comments in the code about >> serious performance problems using VM_PFNMAP / vmf_insert_pfn() with >> write-combining and PAT, so that would require some serious testing with >> hardware I don't have. But I guess there is definitely room for >> improvement here. Ideally we'd like to be able to change the >> vma->vm_page_prot within fault(). But we can > Just a quick comment on this: It's the repeated (per-pfn/pte) lookup > of the PAT tables, which are dead slow. If you have a struct > io_mapping then that can be done once, and then just blindly inserted. > See remap_io_mapping in i915. > -Daniel
Thanks, Daniel.
Indeed looks a lot like remap_pfn_range(), but usable at fault time?
/Thomas
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