From cf1488f8ff7be7d28e74146f7ea06db8ea42c913 Mon Sep 17 00:00:00 2001
From: Matthew Auld <matthew.auld@intel.com>
Date: Wed, 29 Sep 2021 14:26:29 +0100
Subject: drm/ttm: add TTM_TT_FLAG_EXTERNAL_MAPPABLE
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Git-commit: 49e7f76fc514cecf2cad1303fa74d99be7e5d9a6
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
In commit:
commit 667a50db0477d47fdff01c666f5ee1ce26b5264c
Author: Thomas Hellstrom <thellstrom@vmware.com>
Date: Fri Jan 3 11:17:18 2014 +0100
drm/ttm: Refuse to fault (prime-) imported pages
we introduced the restriction that imported pages should not be directly
mappable through TTM(this also extends to userptr). In the next patch we
want to introduce a shmem_tt backend, which should follow all the
existing rules with TTM_PAGE_FLAG_EXTERNAL, since it will need to handle
swapping itself, but with the above mapping restriction lifted.
v2(Christian):
- Don't OR together EXTERNAL and EXTERNAL_MAPPABLE in the definition
of EXTERNAL_MAPPABLE, just leave it the caller to handle this
correctly, otherwise we might encounter subtle issues.
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210929132629.353541-3-matthew.auld@intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/ttm/ttm_bo_vm.c | 6 ++++--
drivers/gpu/drm/ttm/ttm_tt.c | 3 +++
include/drm/ttm/ttm_tt.h | 19 ++++++++++++++++---
3 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 950f4f132802..33680c94127c 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -163,8 +163,10 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
* (if at all) by redirecting mmap to the exporter.
*/
if (bo->ttm && (bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL)) {
- dma_resv_unlock(bo->base.resv);
- return VM_FAULT_SIGBUS;
+ if (!(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL_MAPPABLE)) {
+ dma_resv_unlock(bo->base.resv);
+ return VM_FAULT_SIGBUS;
+ }
}
return 0;
diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 86f31fde6e35..7e83c00a3f48 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -84,6 +84,9 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc)
if (unlikely(bo->ttm == NULL))
return -ENOMEM;
+ WARN_ON(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL_MAPPABLE &&
+ !(bo->ttm->page_flags & TTM_TT_FLAG_EXTERNAL));
+
return 0;
}
diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
index 86d74069be3e..f20832139815 100644
--- a/include/drm/ttm/ttm_tt.h
+++ b/include/drm/ttm/ttm_tt.h
@@ -67,13 +67,26 @@ struct ttm_tt {
* Note that enum ttm_bo_type.ttm_bo_type_sg objects will always enable
* this flag.
*
+ * TTM_TT_FLAG_EXTERNAL_MAPPABLE: Same behaviour as
+ * TTM_TT_FLAG_EXTERNAL, but with the reduced restriction that it is
+ * still valid to use TTM to map the pages directly. This is useful when
+ * implementing a ttm_tt backend which still allocates driver owned
+ * pages underneath(say with shmem).
+ *
+ * Note that since this also implies TTM_TT_FLAG_EXTERNAL, the usage
+ * here should always be:
+ *
+ * page_flags = TTM_TT_FLAG_EXTERNAL |
+ * TTM_TT_FLAG_EXTERNAL_MAPPABLE;
+ *
* TTM_TT_FLAG_PRIV_POPULATED: TTM internal only. DO NOT USE. This is
* set by TTM after ttm_tt_populate() has successfully returned, and is
* then unset when TTM calls ttm_tt_unpopulate().
*/
-#define TTM_TT_FLAG_SWAPPED (1 << 0)
-#define TTM_TT_FLAG_ZERO_ALLOC (1 << 1)
-#define TTM_TT_FLAG_EXTERNAL (1 << 2)
+#define TTM_TT_FLAG_SWAPPED (1 << 0)
+#define TTM_TT_FLAG_ZERO_ALLOC (1 << 1)
+#define TTM_TT_FLAG_EXTERNAL (1 << 2)
+#define TTM_TT_FLAG_EXTERNAL_MAPPABLE (1 << 3)
#define TTM_TT_FLAG_PRIV_POPULATED (1 << 31)
uint32_t page_flags;
--
2.38.1