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>

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;

drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c

@@ -45,11 +45,7 @@
  */
 static inline u64 amdgpu_seq64_get_va_base(struct amdgpu_device *adev)
 {
-	u64 addr = adev->vm_manager.max_pfn << AMDGPU_GPU_PAGE_SHIFT;
-
-	addr -= AMDGPU_VA_RESERVED_TOP;
-
-	return addr;
+	return AMDGPU_VA_RESERVED_SEQ64_START(adev);
 }
 
 /**

drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h

@@ -137,9 +137,18 @@ struct amdgpu_mem_stats;
 
 /* Reserve space at top/bottom of address space for kernel use */
 #define AMDGPU_VA_RESERVED_CSA_SIZE		(2ULL << 20)
+#define AMDGPU_VA_RESERVED_CSA_START(adev)	(((adev)->vm_manager.max_pfn \
+						  << AMDGPU_GPU_PAGE_SHIFT)  \
+						 - AMDGPU_VA_RESERVED_CSA_SIZE)
 #define AMDGPU_VA_RESERVED_SEQ64_SIZE		(2ULL << 20)
+#define AMDGPU_VA_RESERVED_SEQ64_START(adev)	(AMDGPU_VA_RESERVED_CSA_START(adev) \
+						 - AMDGPU_VA_RESERVED_SEQ64_SIZE)
+#define AMDGPU_VA_RESERVED_TRAP_SIZE		(2ULL << 12)
+#define AMDGPU_VA_RESERVED_TRAP_START(adev)	(AMDGPU_VA_RESERVED_SEQ64_START(adev) \
+						 - AMDGPU_VA_RESERVED_TRAP_SIZE)
 #define AMDGPU_VA_RESERVED_BOTTOM		(1ULL << 16)
-#define AMDGPU_VA_RESERVED_TOP			(AMDGPU_VA_RESERVED_SEQ64_SIZE + \
+#define AMDGPU_VA_RESERVED_TOP			(AMDGPU_VA_RESERVED_TRAP_SIZE + \
+						 AMDGPU_VA_RESERVED_SEQ64_SIZE + \
 						 AMDGPU_VA_RESERVED_CSA_SIZE)
 
 /* See vm_update_mode */

drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c

@@ -36,6 +36,7 @@
 #include <linux/mm.h>
 #include <linux/mman.h>
 #include <linux/processor.h>
+#include "amdgpu_vm.h"
 
 /*
  * The primary memory I/O features being added for revisions of gfxip
@@ -326,10 +327,16 @@ static void kfd_init_apertures_vi(struct kfd_process_device *pdd, uint8_t id)
 	 * with small reserved space for kernel.
 	 * Set them to CANONICAL addresses.
 	 */
-	pdd->gpuvm_base = SVM_USER_BASE;
+	pdd->gpuvm_base = max(SVM_USER_BASE, AMDGPU_VA_RESERVED_BOTTOM);
 	pdd->gpuvm_limit =
 		pdd->dev->kfd->shared_resources.gpuvm_size - 1;
 
+	/* dGPUs: the reserved space for kernel
+	 * before SVM
+	 */
+	pdd->qpd.cwsr_base = SVM_CWSR_BASE;
+	pdd->qpd.ib_base = SVM_IB_BASE;
+
 	pdd->scratch_base = MAKE_SCRATCH_APP_BASE_VI();
 	pdd->scratch_limit = MAKE_SCRATCH_APP_LIMIT(pdd->scratch_base);
 }
@@ -339,18 +346,18 @@ static void kfd_init_apertures_v9(struct kfd_process_device *pdd, uint8_t id)
 	pdd->lds_base = MAKE_LDS_APP_BASE_V9();
 	pdd->lds_limit = MAKE_LDS_APP_LIMIT(pdd->lds_base);
 
-        /* Raven needs SVM to support graphic handle, etc. Leave the small
-         * reserved space before SVM on Raven as well, even though we don't
-         * have to.
-         * Set gpuvm_base and gpuvm_limit to CANONICAL addresses so that they
-         * are used in Thunk to reserve SVM.
-         */
-        pdd->gpuvm_base = SVM_USER_BASE;
+	pdd->gpuvm_base = AMDGPU_VA_RESERVED_BOTTOM;
 	pdd->gpuvm_limit =
 		pdd->dev->kfd->shared_resources.gpuvm_size - 1;
 
 	pdd->scratch_base = MAKE_SCRATCH_APP_BASE_V9();
 	pdd->scratch_limit = MAKE_SCRATCH_APP_LIMIT(pdd->scratch_base);
+
+	/*
+	 * Place TBA/TMA on opposite side of VM hole to prevent
+	 * stray faults from triggering SVM on these pages.
+	 */
+	pdd->qpd.cwsr_base = AMDGPU_VA_RESERVED_TRAP_START(pdd->dev->adev);
 }
 
 int kfd_init_apertures(struct kfd_process *process)
@@ -407,12 +414,6 @@ int kfd_init_apertures(struct kfd_process *process)
 					return -EINVAL;
 				}
 			}
-
-                        /* dGPUs: the reserved space for kernel
-                         * before SVM
-                         */
-                        pdd->qpd.cwsr_base = SVM_CWSR_BASE;
-                        pdd->qpd.ib_base = SVM_IB_BASE;
 		}
 
 		dev_dbg(kfd_device, "node id %u\n", id);