Re: [PATCH 1/2] drm/amdkfd: Cleanup IO links during KFD device removal

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Am 2022-04-08 um 04:45 schrieb Shuotao Xu:
Currently, the IO-links to the device being removed from topology,
are not cleared. As a result, there would be dangling links left in
the KFD topology. This patch aims to fix the following:
1. Cleanup all IO links to the device being removed.
2. Ensure that node numbering in sysfs and nodes proximity domain
    values are consistent after the device is removed:
    a. Adding a device and removing a GPU device are made mutually
       exclusive.
    b. The global proximity domain counter is no longer required to be
       an atomic counter. A normal 32-bit counter can be used instead.
3. Update generation_count to let user-mode know that topology has
    changed due to device removal.

Reviewed-by: Shuotao Xu <shuotaoxu@xxxxxxxxxxxxx>
CC: Shuotao Xu <shuotaoxu@xxxxxxxxxxxxx>
Signed-off-by: Mukul Joshi <mukul.joshi@xxxxxxx>

This looks like Mukul's patch, but with you as the author (otherwise I would have expected a "From: Mukul ..." line at the start of the email). Did you make any changes to it?

Regards,
  Felix


---
  drivers/gpu/drm/amd/amdkfd/kfd_crat.c     |  4 +-
  drivers/gpu/drm/amd/amdkfd/kfd_priv.h     |  2 +
  drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 79 ++++++++++++++++++++---
  3 files changed, 74 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
index 1eaabd2cb41b..afc8a7fcdad8 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_crat.c
@@ -1056,7 +1056,7 @@ static int kfd_parse_subtype_iolink(struct crat_subtype_iolink *iolink,
  	 * table, add corresponded reversed direction link now.
  	 */
  	if (props && (iolink->flags & CRAT_IOLINK_FLAGS_BI_DIRECTIONAL)) {
-		to_dev = kfd_topology_device_by_proximity_domain(id_to);
+		to_dev = kfd_topology_device_by_proximity_domain_no_lock(id_to);
  		if (!to_dev)
  			return -ENODEV;
  		/* same everything but the other direction */
@@ -2225,7 +2225,7 @@ static int kfd_create_vcrat_image_gpu(void *pcrat_image,
  	 */
  	if (kdev->hive_id) {
  		for (nid = 0; nid < proximity_domain; ++nid) {
-			peer_dev = kfd_topology_device_by_proximity_domain(nid);
+			peer_dev = kfd_topology_device_by_proximity_domain_no_lock(nid);
  			if (!peer_dev->gpu)
  				continue;
  			if (peer_dev->gpu->hive_id != kdev->hive_id)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index e1b7e6afa920..8a43def1f638 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -1016,6 +1016,8 @@ int kfd_topology_add_device(struct kfd_dev *gpu);
  int kfd_topology_remove_device(struct kfd_dev *gpu);
  struct kfd_topology_device *kfd_topology_device_by_proximity_domain(
  						uint32_t proximity_domain);
+struct kfd_topology_device *kfd_topology_device_by_proximity_domain_no_lock(
+						uint32_t proximity_domain);
  struct kfd_topology_device *kfd_topology_device_by_id(uint32_t gpu_id);
  struct kfd_dev *kfd_device_by_id(uint32_t gpu_id);
  struct kfd_dev *kfd_device_by_pci_dev(const struct pci_dev *pdev);
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
index 3bdcae239bc0..874a273b81f7 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
@@ -46,27 +46,38 @@ static struct list_head topology_device_list;
  static struct kfd_system_properties sys_props;
static DECLARE_RWSEM(topology_lock);
-static atomic_t topology_crat_proximity_domain;
+static uint32_t topology_crat_proximity_domain;
-struct kfd_topology_device *kfd_topology_device_by_proximity_domain(
+struct kfd_topology_device *kfd_topology_device_by_proximity_domain_no_lock(
  						uint32_t proximity_domain)
  {
  	struct kfd_topology_device *top_dev;
  	struct kfd_topology_device *device = NULL;
- down_read(&topology_lock);
-
  	list_for_each_entry(top_dev, &topology_device_list, list)
  		if (top_dev->proximity_domain == proximity_domain) {
  			device = top_dev;
  			break;
  		}
+ return device;
+}
+
+struct kfd_topology_device *kfd_topology_device_by_proximity_domain(
+						uint32_t proximity_domain)
+{
+	struct kfd_topology_device *device = NULL;
+
+	down_read(&topology_lock);
+
+	device = kfd_topology_device_by_proximity_domain_no_lock(
+							proximity_domain);
  	up_read(&topology_lock);
return device;
  }
+
  struct kfd_topology_device *kfd_topology_device_by_id(uint32_t gpu_id)
  {
  	struct kfd_topology_device *top_dev = NULL;
@@ -1060,7 +1071,7 @@ int kfd_topology_init(void)
  	down_write(&topology_lock);
  	kfd_topology_update_device_list(&temp_topology_device_list,
  					&topology_device_list);
-	atomic_set(&topology_crat_proximity_domain, sys_props.num_devices-1);
+	topology_crat_proximity_domain = sys_props.num_devices-1;
  	ret = kfd_topology_update_sysfs();
  	up_write(&topology_lock);
@@ -1295,8 +1306,6 @@ int kfd_topology_add_device(struct kfd_dev *gpu) pr_debug("Adding new GPU (ID: 0x%x) to topology\n", gpu_id); - proximity_domain = atomic_inc_return(&topology_crat_proximity_domain);
-
  	/* Include the CPU in xGMI hive if xGMI connected by assigning it the hive ID. */
  	if (gpu->hive_id && gpu->adev->gmc.xgmi.connected_to_cpu) {
  		struct kfd_topology_device *top_dev;
@@ -1321,12 +1330,16 @@ int kfd_topology_add_device(struct kfd_dev *gpu)
  	 */
  	dev = kfd_assign_gpu(gpu);
  	if (!dev) {
+		down_write(&topology_lock);
+		proximity_domain = ++topology_crat_proximity_domain;
+
  		res = kfd_create_crat_image_virtual(&crat_image, &image_size,
  						    COMPUTE_UNIT_GPU, gpu,
  						    proximity_domain);
  		if (res) {
  			pr_err("Error creating VCRAT for GPU (ID: 0x%x)\n",
  			       gpu_id);
+			topology_crat_proximity_domain--;
  			return res;
  		}
  		res = kfd_parse_crat_table(crat_image,
@@ -1335,10 +1348,10 @@ int kfd_topology_add_device(struct kfd_dev *gpu)
  		if (res) {
  			pr_err("Error parsing VCRAT for GPU (ID: 0x%x)\n",
  			       gpu_id);
+			topology_crat_proximity_domain--;
  			goto err;
  		}
- down_write(&topology_lock);
  		kfd_topology_update_device_list(&temp_topology_device_list,
  			&topology_device_list);
@@ -1485,25 +1498,73 @@ int kfd_topology_add_device(struct kfd_dev *gpu)
  	return res;
  }
+static void kfd_topology_update_io_links(int proximity_domain)
+{
+	struct kfd_topology_device *dev;
+	struct kfd_iolink_properties *iolink, *p2plink, *tmp;
+	/*
+	 * The topology list currently is arranged in increasing
+	 * order of proximity domain.
+	 *
+	 * Two things need to be done when a device is removed:
+	 * 1. All the IO links to this device need to be
+	 *    removed.
+	 * 2. All nodes after the current device node need to move
+	 *    up once this device node is removed from the topology
+	 *    list. As a result, the proximity domain values for
+	 *    all nodes after the node being deleted reduce by 1.
+	 *    This would also cause the proximity domain values for
+	 *    io links to be updated based on new proximity
+	 *    domain values.
+	 */
+	list_for_each_entry(dev, &topology_device_list, list) {
+		if (dev->proximity_domain > proximity_domain)
+			dev->proximity_domain--;
+
+		list_for_each_entry_safe(iolink, tmp, &dev->io_link_props, list) {
+			/*
+			 * If there is an io link to the dev being deleted
+			 * then remove that IO link also.
+			 */
+			if (iolink->node_to == proximity_domain) {
+				list_del(&iolink->list);
+				dev->io_link_count--;
+				dev->node_props.io_links_count--;
+			} else if (iolink->node_from > proximity_domain) {
+				iolink->node_from--;
+			} else if (iolink->node_to > proximity_domain) {
+				iolink->node_to--;
+			}
+		}
+
+	}
+}
+
  int kfd_topology_remove_device(struct kfd_dev *gpu)
  {
  	struct kfd_topology_device *dev, *tmp;
  	uint32_t gpu_id;
  	int res = -ENODEV;
+	int i = 0;
down_write(&topology_lock); - list_for_each_entry_safe(dev, tmp, &topology_device_list, list)
+	list_for_each_entry_safe(dev, tmp, &topology_device_list, list) {
  		if (dev->gpu == gpu) {
  			gpu_id = dev->gpu_id;
  			kfd_remove_sysfs_node_entry(dev);
  			kfd_release_topology_device(dev);
  			sys_props.num_devices--;
+			kfd_topology_update_io_links(i);
+			topology_crat_proximity_domain = sys_props.num_devices-1;
+			sys_props.generation_count++;
  			res = 0;
  			if (kfd_topology_update_sysfs() < 0)
  				kfd_topology_release_sysfs();
  			break;
  		}
+		i++;
+	}
up_write(&topology_lock);



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