From cfb6304d5e53816cefdcca458bad28e7e51b5320 Mon Sep 17 00:00:00 2001
From: Alex Sierra <alex.sierra@amd.com>
Date: Wed, 3 Nov 2021 21:06:31 -0500
Subject: drm/amdkfd: lower the VAs base offset to 8KB
Git-commit: 3aac6aa6304f263641880e5769457ec998fb0d97
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

The low 16MB of virtual address space are currently reserved for kernel
mode allocations mapped into user virtual address space. This causes
conflicts with HMM/SVM mappings at low virtual addresses. We tried to
move those kernel mode allocations to the upper half of the 64-bit
virtual address space for GFX9, which is naturally reserved for kernel
use. However, TBA (trap handler code) has problems to access addresses
in the high virtual space. We have decided to set this to 8KB of the
lower address space as a temporary fix, while investigate TBA address
problem. It is very unlikely for user space to map memory at this low
region.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c b/drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c
index 2e86692def19..d1388896f9c1 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_flat_memory.c
@@ -308,7 +308,7 @@
  * 16MB are reserved for kernel use (CWSR trap handler and kernel IB
  * for now).
  */
-#define SVM_USER_BASE 0x1000000ull
+#define SVM_USER_BASE (u64)(KFD_CWSR_TBA_TMA_SIZE + 2*PAGE_SIZE)
 #define SVM_CWSR_BASE (SVM_USER_BASE - KFD_CWSR_TBA_TMA_SIZE)
 #define SVM_IB_BASE   (SVM_CWSR_BASE - PAGE_SIZE)
 
-- 
2.38.1