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 <Arunpravin.PaneerSelvam@amd.com>
Cc: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Signed-off-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c
index b5ad56690a9d..cfdf558b48b6 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_csa.c
@@ -28,9 +28,8 @@
 
 uint64_t amdgpu_csa_vaddr(struct amdgpu_device *adev)
 {
-	uint64_t addr = adev->vm_manager.max_pfn << AMDGPU_GPU_PAGE_SHIFT;
+	uint64_t addr = AMDGPU_VA_RESERVED_CSA_START(adev);
 
-	addr -= AMDGPU_VA_RESERVED_CSA_SIZE;
 	addr = amdgpu_gmc_sign_extend(addr);
 
 	return addr;