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charset="UTF-8" Content-Transfer-Encoding: quoted-printable It is mapped, via iommu interface (vfio-iommu) when map_dma is called. -- Dominik On Mon, Mar 25, 2024 at 7:38=E2=80=AFPM Rob Clark wro= te: > > This is actually a bit concerning.. importing a host page backed > buffer without guest mapping into a passthru device probably doesn't > work and should be rejected earlier. > > I do think we should relax the restriction (either taking my patch or > reverting the commit it fixes) until we work this out properly > (because the original patch is a regression), but importing a buffer > without guest pages into a passthru device can't possibly work > properly. Maybe it works by chance if the host buffer is mapped to > the guest, but that is not guaranteed. > > BR, > -R > > On Mon, Mar 25, 2024 at 3:35=E2=80=AFPM Dominik Behr = wrote: > > > > It also fixes importing virtgpu blobs into real hardware, for instance = amdgpu for DRI_PRIME rendering. > > > > On Fri, Mar 22, 2024 at 2:48=E2=80=AFPM Rob Clark = wrote: > >> > >> From: Rob Clark > >> > >> virtgpu "vram" GEM objects do not implement obj->get_sg_table(). But > >> they also don't use drm_gem_map_dma_buf(). In fact they may not even > >> have guest visible pages. But it is perfectly fine to export and shar= e > >> with other virtual devices. > >> > >> Reported-by: Dominik Behr > >> Fixes: 207395da5a97 ("drm/prime: reject DMA-BUF attach when get_sg_tab= le is missing") > >> Signed-off-by: Rob Clark > >> --- > >> drivers/gpu/drm/drm_prime.c | 7 ++++++- > >> 1 file changed, 6 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c > >> index 7352bde299d5..64dd6276e828 100644 > >> --- a/drivers/gpu/drm/drm_prime.c > >> +++ b/drivers/gpu/drm/drm_prime.c > >> @@ -582,7 +582,12 @@ int drm_gem_map_attach(struct dma_buf *dma_buf, > >> { > >> struct drm_gem_object *obj =3D dma_buf->priv; > >> > >> - if (!obj->funcs->get_sg_table) > >> + /* > >> + * drm_gem_map_dma_buf() requires obj->get_sg_table(), but dri= vers > >> + * that implement their own ->map_dma_buf() do not. > >> + */ > >> + if ((dma_buf->ops->map_dma_buf =3D=3D drm_gem_map_dma_buf) && > >> + !obj->funcs->get_sg_table) > >> return -ENOSYS; > >> > >> return drm_gem_pin(obj); > >> -- > >> 2.44.0 > >>