[AMD Official Use Only]
> -----Original Message-----
> From: Kuehling, Felix <Felix.Kuehling@xxxxxxx>
> Sent: Monday, April 11, 2022 8:16 PM
> To: Joshi, Mukul <Mukul.Joshi@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx
> Cc: Shuotao Xu <shuotaoxu@xxxxxxxxxxxxx>
> Subject: Re: [PATCH] drm/amdkfd: Cleanup IO links during KFD device
> removal
>
> Am 2022-04-07 um 12:15 schrieb Mukul Joshi:
> > 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.
> >
> > CC: Shuotao Xu <shuotaoxu@xxxxxxxxxxxxx>
> > Signed-off-by: Mukul Joshi <mukul.joshi@xxxxxxx>
>
> Looks good to me. I have two nit-picks inline.
>
>
> > ---
> > 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)
>
> I remember we discussed this and I suggested splitting a no_lock version out
> of this function. But now I don't see it being used anywhere. Was that lost
> somewhere in refactoring or porting to the upstream branch?
> Maybe the no_lock version isn't needed any more.
>
Its used in the changes in kfd_crat.c (in kfd_create_vcrat_image_gpu() and
kfd_parse_subtype_iolink ()) and below in kfd_topology_device_by_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.
> > + */
>
> I'd put this comment in front of the function, not in the middle of it.
> You can make it a proper kernel-doc comment, especially since the function
> name is a bit generic (and I can't think of a better one that isn't excessively
> long).
>
Sure will do that and send a v2.
Regards,
Mukul
> Regards,
> Felix
>
>
> > + 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);
> >
