Hi,
Hmm, virtio-gpu uses the dma api to allow the host access the gemNot clue about the others (lima, tiny, panfrost, v3d). Maybe they useDecrypted here is clearly incorrect and violates the SEV spec, regardless of
write-combine just because this is what they got by default from
drm_gem_mmap_obj(). Maybe they actually need that. Trying to Cc:
maintainters (and drop stable@).
virtio-gpu needs it, otherwise the host can't show the virtual display.
cirrus bounces everything via blits to vram, so it should be ok without
decrypted. I guess that implies we should make decrypted configurable.
a config option.
The only correct way is currently to use dma_alloc_coherent() and
mmap_coherent() to allocate decrypted memory and then use the
pgprot_decrypted flag.
object. So I think I have to correct the statement above, if I
understands things correctly the dma api will use (properly allocated)
decrypted bounce buffers and the virtio-gpu shmem objects don't need
pgprot_decrypted mappings.
That leaves the question what to do about pgprot_writecombine(). Any
comments from the driver maintainers (see first paragraph)?
cheers,
Gerd