[PATCH 0/2] drm/msm: fix dma-buf sharing on targets without per-process pgtables

[Dmitry Baryshkov]

Targets without per-process pgtables -- everything pre-a6xx, plus a6xx
parts where split pagetables are unavailable -- hand every DRM file the
GPU's global VM.  The rest of the driver still treats a context VM as
private to that context, so closing a handle tears down mappings other
files are still using, and frees the iova for immediate reuse.

A dma-buf shared between two clients therefore keeps sampling an address
that the next allocation has taken over.  On a530 this is every
ext_image_dma_buf_import sampling test, reading back all zeros.

A VM shared between contexts needs the lazy, refcounted teardown the
driver already implements for kms->vm.  Rather than adding a second
mechanism, the first patch makes that machinery reusable and the second
one puts the shared GPU VM behind it.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
---
Dmitry Baryshkov (2):
      drm/msm: factor out a locking put_iova_spaces() wrapper
      drm/msm: don't tear down shared VM mappings on handle close

 drivers/gpu/drm/msm/msm_gem.c | 45 ++++++++++++++++++++++++++++---------------
 drivers/gpu/drm/msm/msm_gpu.c |  4 +++-
 drivers/gpu/drm/msm/msm_gpu.h |  3 +++
 3 files changed, 36 insertions(+), 16 deletions(-)
---
base-commit: 6b8c8af514d739d0335f5579b585e02babe8a727
change-id: 20260822-msm-fix-export-c4a4cd9239fc

Best regards,
--  
With best wishes
Dmitry