[PATCH v2] drm/amdgpu: Put drm_dev_enter/exit outside hot codepath

[xinhui pan <xinhui.pan@amd.com>]

We hit soft hang while doing memory pressure test on one numa system.
After a qucik look, this is because kfd invalid/valid userptr memory
frequently with process_info lock hold.
Looks like update page table mapping use too much cpu time.

perf top says below,
75.81%  [kernel]       [k] __srcu_read_unlock
 6.19%  [amdgpu]       [k] amdgpu_gmc_set_pte_pde
 3.56%  [kernel]       [k] __srcu_read_lock
 2.20%  [amdgpu]       [k] amdgpu_vm_cpu_update
 2.20%  [kernel]       [k] __sg_page_iter_dma_next
 2.15%  [drm]          [k] drm_dev_enter
 1.70%  [drm]          [k] drm_prime_sg_to_dma_addr_array
 1.18%  [kernel]       [k] __sg_alloc_table_from_pages
 1.09%  [drm]          [k] drm_dev_exit

So move drm_dev_enter/exit outside gmc code, instead let caller do it.
They are gart_unbind, gart_map, vm_clear_bo, vm_update_pdes and
gmc_init_pdb0. vm_bo_update_mapping already calls it.

Signed-off-by: xinhui pan <xinhui.pan@amd.com>
---
change from v1:
add enter/exit in more gmc_set_pte_pde callers
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c | 11 ++++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c  | 11 +++++-----
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c   | 28 +++++++++++++++++-------
 3 files changed, 36 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c
index 76efd5f8950f..d7e4f4660acf 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c
@@ -34,6 +34,7 @@
 #include <asm/set_memory.h>
 #endif
 #include "amdgpu.h"
+#include <drm/drm_drv.h>
 
 /*
  * GART
@@ -230,12 +231,16 @@ int amdgpu_gart_unbind(struct amdgpu_device *adev, uint64_t offset,
 	u64 page_base;
 	/* Starting from VEGA10, system bit must be 0 to mean invalid. */
 	uint64_t flags = 0;
+	int idx;
 
 	if (!adev->gart.ready) {
 		WARN(1, "trying to unbind memory from uninitialized GART !\n");
 		return -EINVAL;
 	}
 
+	if (!drm_dev_enter(&adev->ddev, &idx))
+		return 0;
+
 	t = offset / AMDGPU_GPU_PAGE_SIZE;
 	p = t / AMDGPU_GPU_PAGES_IN_CPU_PAGE;
 	for (i = 0; i < pages; i++, p++) {
@@ -254,6 +259,7 @@ int amdgpu_gart_unbind(struct amdgpu_device *adev, uint64_t offset,
 	for (i = 0; i < adev->num_vmhubs; i++)
 		amdgpu_gmc_flush_gpu_tlb(adev, 0, i, 0);
 
+	drm_dev_exit(idx);
 	return 0;
 }
 
@@ -276,12 +282,16 @@ int amdgpu_gart_map(struct amdgpu_device *adev, uint64_t offset,
 {
 	uint64_t page_base;
 	unsigned i, j, t;
+	int idx;
 
 	if (!adev->gart.ready) {
 		WARN(1, "trying to bind memory to uninitialized GART !\n");
 		return -EINVAL;
 	}
 
+	if (!drm_dev_enter(&adev->ddev, &idx))
+		return 0;
+
 	t = offset / AMDGPU_GPU_PAGE_SIZE;
 
 	for (i = 0; i < pages; i++) {
@@ -291,6 +301,7 @@ int amdgpu_gart_map(struct amdgpu_device *adev, uint64_t offset,
 			page_base += AMDGPU_GPU_PAGE_SIZE;
 		}
 	}
+	drm_dev_exit(idx);
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
index 54f059501a33..1427fd70310c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
@@ -153,10 +153,6 @@ int amdgpu_gmc_set_pte_pde(struct amdgpu_device *adev, void *cpu_pt_addr,
 {
 	void __iomem *ptr = (void *)cpu_pt_addr;
 	uint64_t value;
-	int idx;
-
-	if (!drm_dev_enter(&adev->ddev, &idx))
-		return 0;
 
 	/*
 	 * The following is for PTE only. GART does not have PDEs.
@@ -165,8 +161,6 @@ int amdgpu_gmc_set_pte_pde(struct amdgpu_device *adev, void *cpu_pt_addr,
 	value |= flags;
 	writeq(value, ptr + (gpu_page_idx * 8));
 
-	drm_dev_exit(idx);
-
 	return 0;
 }
 
@@ -752,6 +746,10 @@ void amdgpu_gmc_init_pdb0(struct amdgpu_device *adev)
 		adev->gmc.xgmi.physical_node_id * adev->gmc.xgmi.node_segment_size;
 	u64 vram_end = vram_addr + vram_size;
 	u64 gart_ptb_gpu_pa = amdgpu_gmc_vram_pa(adev, adev->gart.bo);
+	int idx;
+
+	if (!drm_dev_enter(&adev->ddev, &idx))
+		return;
 
 	flags |= AMDGPU_PTE_VALID | AMDGPU_PTE_READABLE;
 	flags |= AMDGPU_PTE_WRITEABLE;
@@ -773,6 +771,7 @@ void amdgpu_gmc_init_pdb0(struct amdgpu_device *adev)
 	flags |= AMDGPU_PDE_BFS(0) | AMDGPU_PTE_SNOOPED;
 	/* Requires gart_ptb_gpu_pa to be 4K aligned */
 	amdgpu_gmc_set_pte_pde(adev, adev->gmc.ptr_pdb0, i, gart_ptb_gpu_pa, flags);
+	drm_dev_exit(idx);
 }
 
 /**
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 0126ece898da..daa16d2f89da 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -800,7 +800,7 @@ static int amdgpu_vm_clear_bo(struct amdgpu_device *adev,
 	struct amdgpu_bo *bo = &vmbo->bo;
 	unsigned entries, ats_entries;
 	uint64_t addr;
-	int r;
+	int r, idx;
 
 	/* Figure out our place in the hierarchy */
 	if (ancestor->parent) {
@@ -845,9 +845,12 @@ static int amdgpu_vm_clear_bo(struct amdgpu_device *adev,
 			return r;
 	}
 
+	if (!drm_dev_enter(&adev->ddev, &idx))
+		return -ENODEV;
+
 	r = vm->update_funcs->map_table(vmbo);
 	if (r)
-		return r;
+		goto exit;
 
 	memset(&params, 0, sizeof(params));
 	params.adev = adev;
@@ -856,7 +859,7 @@ static int amdgpu_vm_clear_bo(struct amdgpu_device *adev,
 
 	r = vm->update_funcs->prepare(&params, NULL, AMDGPU_SYNC_EXPLICIT);
 	if (r)
-		return r;
+		goto exit;
 
 	addr = 0;
 	if (ats_entries) {
@@ -872,7 +875,7 @@ static int amdgpu_vm_clear_bo(struct amdgpu_device *adev,
 		r = vm->update_funcs->update(&params, vmbo, addr, 0, ats_entries,
 					     value, flags);
 		if (r)
-			return r;
+			goto exit;
 
 		addr += ats_entries * 8;
 	}
@@ -895,10 +898,13 @@ static int amdgpu_vm_clear_bo(struct amdgpu_device *adev,
 		r = vm->update_funcs->update(&params, vmbo, addr, 0, entries,
 					     value, flags);
 		if (r)
-			return r;
+			goto exit;
 	}
 
-	return vm->update_funcs->commit(&params, NULL);
+	r = vm->update_funcs->commit(&params, NULL);
+exit:
+	drm_dev_exit(idx);
+	return r;
 }
 
 /**
@@ -1384,11 +1390,14 @@ int amdgpu_vm_update_pdes(struct amdgpu_device *adev,
 			  struct amdgpu_vm *vm, bool immediate)
 {
 	struct amdgpu_vm_update_params params;
-	int r;
+	int r, idx;
 
 	if (list_empty(&vm->relocated))
 		return 0;
 
+	if (!drm_dev_enter(&adev->ddev, &idx))
+		return -ENODEV;
+
 	memset(&params, 0, sizeof(params));
 	params.adev = adev;
 	params.vm = vm;
@@ -1396,7 +1405,7 @@ int amdgpu_vm_update_pdes(struct amdgpu_device *adev,
 
 	r = vm->update_funcs->prepare(&params, NULL, AMDGPU_SYNC_EXPLICIT);
 	if (r)
-		return r;
+		goto exit;
 
 	while (!list_empty(&vm->relocated)) {
 		struct amdgpu_vm_bo_base *entry;
@@ -1414,10 +1423,13 @@ int amdgpu_vm_update_pdes(struct amdgpu_device *adev,
 	r = vm->update_funcs->commit(&params, &vm->last_update);
 	if (r)
 		goto error;
+	drm_dev_exit(idx);
 	return 0;
 
 error:
 	amdgpu_vm_invalidate_pds(adev, vm);
+exit:
+	drm_dev_exit(idx);
 	return r;
 }
 
-- 
2.25.1