drm/amdkfd: Relocate TBA/TMA to opposite side of VM hole

The TBA and TMA, along with an unused IB allocation, reside at low
addresses in the VM address space. A stray VM fault which hits these
pages must be serviced by making their page table entries invalid.
The scheduler depends upon these pages being resident and fails,
preventing a debugger from inspecting the failure state.

By relocating these pages above 47 bits in the VM address space they
can only be reached when bits [63:48] are set to 1. This makes it much
less likely for a misbehaving program to generate accesses to them.
The current placement at VA (PAGE_SIZE*2) is readily hit by a NULL
access with a small offset.

v2:
- Move it to the reserved space to avoid concflicts with Mesa
- Add macros to make reserved space management easier

v3:
- Move VM  max PFN calculation into AMDGPU_VA_RESERVED macros

Cc: Arunpravin Paneer Selvam <[email protected]>
Cc: Christian Koenig <[email protected]>
Reviewed-by: Christian König <[email protected]>
Signed-off-by: Jay Cornwall <[email protected]>
Signed-off-by: Felix Kuehling <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

0 files changed, 0 insertions, 0 deletions