Am 01.03.24 um 12:07 schrieb Shashank Sharma:
The idea behind this patch is to delay the freeing of PT entry objects
until the TLB flush is done.
This patch:
- Adds a tlb_flush_waitlist which will keep the objects that need to be
freed after tlb_flush
- Adds PT entries in this list in amdgpu_vm_pt_free_dfs, instead of freeing
them immediately.
- Exports function amdgpu_vm_pt_free to be called dircetly.
- Adds a 'force' input bool to amdgpu_vm_pt_free_dfs to differentiate
between immediate freeing of the BOs (like from
amdgpu_vm_pt_free_root) vs delayed freeing.
V2: rebase
V4: (Christian)
- add only locked PTEs entries in TLB flush waitlist.
- do not create a separate function for list flush.
- do not create a new lock for TLB flush.
- there is no need to wait on tlb_flush_fence exclusively.
Cc: Christian König <Christian.Koenig@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Felix Kuehling <felix.kuehling@xxxxxxx>
Cc: Rajneesh Bhardwaj <rajneesh.bhardwaj@xxxxxxx>
Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 10 ++++++++++
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h | 4 ++++
drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c | 21 ++++++++++++++-------
3 files changed, 28 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 310aae6fb49b..94581a1fe34f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -990,11 +990,20 @@ int amdgpu_vm_update_range(struct amdgpu_device *adev, struct amdgpu_vm *vm,
/* Prepare a TLB flush fence to be attached to PTs */
if (!unlocked && params.needs_flush && vm->is_compute_context) {
+ struct amdgpu_vm_bo_base *entry, *next;
+
amdgpu_vm_tlb_fence_create(adev, vm, fence);
/* Makes sure no PD/PT is freed before the flush */
dma_resv_add_fence(vm->root.bo->tbo.base.resv, *fence,
DMA_RESV_USAGE_BOOKKEEP);
+
+ if (list_empty(&vm->tlb_flush_waitlist))
+ goto error_unlock;
+
+ /* Now actually free the waitlist */
+ list_for_each_entry_safe(entry, next, &vm->tlb_flush_waitlist, vm_status)
+ amdgpu_vm_pt_free(entry);
This needs to be outside of the "if". We also need to free the PDs/PTs
in non compute VMs.
}
error_unlock:
@@ -2214,6 +2223,7 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
INIT_LIST_HEAD(&vm->pt_freed);
INIT_WORK(&vm->pt_free_work, amdgpu_vm_pt_free_work);
INIT_KFIFO(vm->faults);
+ INIT_LIST_HEAD(&vm->tlb_flush_waitlist);
r = amdgpu_seq64_alloc(adev, &vm->tlb_seq_va, &vm->tlb_seq_cpu_addr);
if (r)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
index 298f604b8e5f..ba374c2c61bd 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.h
@@ -343,6 +343,9 @@ struct amdgpu_vm {
uint64_t *tlb_seq_cpu_addr;
uint64_t tlb_fence_context;
+ /* temporary storage of PT BOs until the TLB flush */
+ struct list_head tlb_flush_waitlist;
+
atomic64_t kfd_last_flushed_seq;
/* How many times we had to re-generate the page tables */
@@ -545,6 +548,7 @@ int amdgpu_vm_ptes_update(struct amdgpu_vm_update_params *params,
uint64_t start, uint64_t end,
uint64_t dst, uint64_t flags);
void amdgpu_vm_pt_free_work(struct work_struct *work);
+void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry);
#if defined(CONFIG_DEBUG_FS)
void amdgpu_debugfs_vm_bo_info(struct amdgpu_vm *vm, struct seq_file *m);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
index 95dc0afdaffb..cb14e5686c0f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm_pt.c
@@ -636,7 +636,7 @@ static int amdgpu_vm_pt_alloc(struct amdgpu_device *adev,
*
* @entry: PDE to free
*/
-static void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry)
+void amdgpu_vm_pt_free(struct amdgpu_vm_bo_base *entry)
{
struct amdgpu_bo *shadow;
@@ -685,13 +685,15 @@ void amdgpu_vm_pt_free_work(struct work_struct *work)
* @vm: amdgpu vm structure
* @start: optional cursor where to start freeing PDs/PTs
* @unlocked: vm resv unlock status
+ * @force: force free all PDs/PTs without waiting for TLB flush
*
* Free the page directory or page table level and all sub levels.
*/
static void amdgpu_vm_pt_free_dfs(struct amdgpu_device *adev,
struct amdgpu_vm *vm,
struct amdgpu_vm_pt_cursor *start,
- bool unlocked)
+ bool unlocked,
+ bool force)
{
struct amdgpu_vm_pt_cursor cursor;
struct amdgpu_vm_bo_base *entry;
@@ -708,11 +710,15 @@ static void amdgpu_vm_pt_free_dfs(struct amdgpu_device *adev,
return;
}
- for_each_amdgpu_vm_pt_dfs_safe(adev, vm, start, cursor, entry)
- amdgpu_vm_pt_free(entry);
+ for_each_amdgpu_vm_pt_dfs_safe(adev, vm, start, cursor, entry) {
+ if (!force)
+ list_move(&entry->vm_status, &vm->tlb_flush_waitlist);
+ else
+ amdgpu_vm_pt_free(entry);
+ }
if (start)
- amdgpu_vm_pt_free(start->entry);
+ list_move(&start->entry->vm_status, &vm->tlb_flush_waitlist);
}
The complexity inside amdgpu_vm_pt_free_dfs() really starts to make no
sense any more.
First of all ditch the usage in amdgpu_vm_pt_free_root(). Instead just
inline the call to for_each_amdgpu_vm_pt_dfs_safe() to free up all of
the page tables immediately.
Then the other use case in amdgpu_vm_ptes_update():
/* Make sure previous mapping is freed */
if (cursor.entry->bo) {
params->table_freed = true;
amdgpu_vm_pt_free_dfs(adev, params->vm, &cursor, params->unlocked);
}
We should basically change params->table_freed into a list_head and put
all to be freed entries on there. Something like that:
spin_lock(&vm->status_lock);
for_each_amdgpu_vm_pt_dfs_safe(adev, vm, start, cursor, entry)
list_move(&entry->vm_status, ¶ms->table_freed);
spin_unlock(&vm->status_lock);
And then finally in amdgpu_vm_update_range() we should call
amdgpu_vm_pt_free_dfs() to really free up all PDs/PTs (probably rename
the function while at it).
Regards,
Christian.
/**
@@ -724,7 +730,7 @@ static void amdgpu_vm_pt_free_dfs(struct amdgpu_device *adev,
*/
void amdgpu_vm_pt_free_root(struct amdgpu_device *adev, struct amdgpu_vm *vm)
{
- amdgpu_vm_pt_free_dfs(adev, vm, NULL, false);
+ amdgpu_vm_pt_free_dfs(adev, vm, NULL, false, true);
}
/**
@@ -1059,7 +1065,8 @@ int amdgpu_vm_ptes_update(struct amdgpu_vm_update_params *params,
params->needs_flush = true;
amdgpu_vm_pt_free_dfs(adev, params->vm,
&cursor,
- params->unlocked);
+ params->unlocked,
+ false);
}
amdgpu_vm_pt_next(adev, &cursor);
}
