On Mon, Dec 01, 2025 at 05:44:47PM +0000, Jonathan Cavitt wrote:
> Add additional information to each VM so they can report up to the first
> 50 seen faults. Only pagefaults are saved this way currently, though in
> the future, all faults should be tracked by the VM for future reporting.
>
> Additionally, of the pagefaults reported, only failed pagefaults are
> saved this way, as successful pagefaults should recover silently and not
> need to be reported to userspace.
>
> v2:
> - Free vm after use (Shuicheng)
> - Compress pf copy logic (Shuicheng)
> - Update fault_unsuccessful before storing (Shuicheng)
> - Fix old struct name in comments (Shuicheng)
> - Keep first 50 pagefaults instead of last 50 (Jianxun)
>
> v3:
> - Avoid unnecessary execution by checking MAX_PFS earlier (jcavitt)
> - Fix double-locking error (jcavitt)
> - Assert kmemdump is successful (Shuicheng)
>
> v4:
> - Rename xe_vm.pfs to xe_vm.faults (jcavitt)
> - Store fault data and not pagefault in xe_vm faults list (jcavitt)
> - Store address, address type, and address precision per fault (jcavitt)
> - Store engine class and instance data per fault (Jianxun)
> - Add and fix kernel docs (Michal W)
> - Properly handle kzalloc error (Michal W)
> - s/MAX_PFS/MAX_FAULTS_SAVED_PER_VM (Michal W)
> - Store fault level per fault (Micahl M)
>
> v5:
> - Store fault and access type instead of address type (Jianxun)
>
> v6:
> - Store pagefaults in non-fault-mode VMs as well (Jianxun)
>
> v7:
> - Fix kernel docs and comments (Michal W)
>
> v8:
> - Fix double-locking issue (Jianxun)
>
> v9:
> - Do not report faults from reserved engines (Jianxun)
>
> v10:
> - Remove engine class and instance (Ivan)
>
> v11:
> - Perform kzalloc outside of lock (Auld)
>
> v12:
> - Fix xe_vm_fault_entry kernel docs (Shuicheng)
>
> v13:
> - Rebase and refactor (jcavitt)
>
> v14:
> - Correctly ignore fault mode in save_pagefault_to_vm (jcavitt)
>
> Signed-off-by: Jonathan Cavitt <[email protected]>
> Suggested-by: Matthew Brost <[email protected]>
> Cc: Shuicheng Lin <[email protected]>
> Cc: Jianxun Zhang <[email protected]>
> Cc: Michal Wajdeczko <[email protected]>
> Cc: Michal Mzorek <[email protected]>
> Cc: Ivan Briano <[email protected]>
> Cc: Matthew Auld <[email protected]>
> ---
> drivers/gpu/drm/xe/xe_pagefault.c | 26 +++++++++
> drivers/gpu/drm/xe/xe_vm.c | 88 +++++++++++++++++++++++++++++++
> drivers/gpu/drm/xe/xe_vm.h | 9 ++++
> drivers/gpu/drm/xe/xe_vm_types.h | 29 ++++++++++
> 4 files changed, 152 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/xe_pagefault.c
> b/drivers/gpu/drm/xe/xe_pagefault.c
> index 0b625a52a598..5997023a5889 100644
> --- a/drivers/gpu/drm/xe/xe_pagefault.c
> +++ b/drivers/gpu/drm/xe/xe_pagefault.c
> @@ -247,6 +247,31 @@ static void xe_pagefault_print(struct xe_pagefault *pf)
> pf->consumer.engine_instance);
> }
>
> +static void save_pagefault_to_vm(struct xe_device *xe, struct xe_pagefault
> *pf)
Every function in xe_pagefault.c starts with 'xe_pagefault_'
So maybe: s/save_pagefault_to_vm/xe_pagefault_save_to_vm
> +{
> + struct xe_vm *vm;
> +
> + /*
> + * Pagefault may be asociated to VM that is not in fault mode.
> + * Perform asid_to_vm behavior, except if VM is not in fault
> + * mode, return VM anyways.
> + */
> + down_read(&xe->usm.lock);
> + vm = xa_load(&xe->usm.asid_to_vm, pf->consumer.asid);
> + if (vm)
> + xe_vm_get(vm);
> + else
> + vm = ERR_PTR(-EINVAL);
> + up_read(&xe->usm.lock);
> +
> + if (IS_ERR(vm))
> + return;
> +
> + xe_vm_add_fault_entry_pf(vm, pf);
> +
> + xe_vm_put(vm);
> +}
> +
> static void xe_pagefault_queue_work(struct work_struct *w)
> {
> struct xe_pagefault_queue *pf_queue =
> @@ -266,6 +291,7 @@ static void xe_pagefault_queue_work(struct work_struct *w)
> err = xe_pagefault_service(&pf);
> if (err) {
> xe_pagefault_print(&pf);
> + save_pagefault_to_vm(gt_to_xe(pf.gt), &pf);
> xe_gt_dbg(pf.gt, "Fault response: Unsuccessful %pe\n",
> ERR_PTR(err));
> }
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 8ab726289583..e69e10233b00 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -27,6 +27,7 @@
> #include "xe_device.h"
> #include "xe_drm_client.h"
> #include "xe_exec_queue.h"
> +#include "xe_gt.h"
> #include "xe_migrate.h"
> #include "xe_pat.h"
> #include "xe_pm.h"
> @@ -578,6 +579,88 @@ static void preempt_rebind_work_func(struct work_struct
> *w)
> trace_xe_vm_rebind_worker_exit(vm);
> }
>
> +static struct xe_hw_engine *
> +hw_engine_lookup_class_instance(struct xe_vm *vm,
> + enum xe_engine_class class,
> + u16 instance)
Can we use xe_hw_engine_lookup or xe_gt_hw_engine rather than adding a
new helper?
> +{
> + struct xe_device *xe = vm->xe;
> + struct xe_hw_engine *hwe;
> + enum xe_hw_engine_id id;
> + struct xe_gt *gt;
> + u8 gt_id;
> +
> + for_each_gt(gt, xe, gt_id)
> + for_each_hw_engine(hwe, gt, id)
> + if (hwe->class == class && hwe->instance == instance)
> + return hwe;
> + return NULL;
> +}
> +
> +/**
> + * xe_vm_add_fault_entry_pf() - Add pagefault to vm fault list
> + * @vm: The VM.
> + * @pf: The pagefault.
> + *
> + * This function takes the data from the pagefault @pf and saves it to
> @vm->faults.list.
> + *
> + * The function exits silently if the list is full, and reports a warning if
> the pagefault
> + * could not be saved to the list.
> + */
> +void xe_vm_add_fault_entry_pf(struct xe_vm *vm, struct xe_pagefault *pf)
> +{
> + struct xe_vm_fault_entry *e = NULL;
> + struct xe_hw_engine *hwe;
> +
> + /* Do not report faults on reserved engines */
> + hwe = hw_engine_lookup_class_instance(vm, pf->consumer.engine_class,
> + pf->consumer.engine_instance);
> + if (!hwe || xe_hw_engine_is_reserved(hwe))
> + return;
> +
> + e = kzalloc(sizeof(*e), GFP_KERNEL);
> + if (!e) {
> + drm_warn(&vm->xe->drm,
> + "Could not allocate memory for fault!\n");
> + return;
> + }
> +
> + spin_lock(&vm->faults.lock);
> +
Michal would say use guard(spinlock)(&vm->faults.lock) here. Probably
a little cleaner as the goto can be avoided.
> + /*
> + * Limit the number of faults in the fault list to prevent
> + * memory overuse.
> + */
> + if (vm->faults.len >= MAX_FAULTS_SAVED_PER_VM) {
> + kfree(e);
> + goto out;
> + }
> +
> + e->address = pf->consumer.page_addr;
> + e->address_precision = 1;
> + e->access_type = pf->consumer.access_type;
> + e->fault_type = pf->consumer.fault_type;
> + e->fault_level = pf->consumer.fault_level;
> +
> + list_add_tail(&e->list, &vm->faults.list);
> + vm->faults.len++;
> +out:
> + spin_unlock(&vm->faults.lock);
> +}
> +
> +static void xe_vm_clear_fault_entries(struct xe_vm *vm)
> +{
> + struct xe_vm_fault_entry *e, *tmp;
> +
> + spin_lock(&vm->faults.lock);
Probably a guard here too.
Nits aside, overall LGTM.
Matt
> + list_for_each_entry_safe(e, tmp, &vm->faults.list, list) {
> + list_del(&e->list);
> + kfree(e);
> + }
> + vm->faults.len = 0;
> + spin_unlock(&vm->faults.lock);
> +}
> +
> static int xe_vma_ops_alloc(struct xe_vma_ops *vops, bool array_of_binds)
> {
> int i;
> @@ -1503,6 +1586,9 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32
> flags, struct xe_file *xef)
> INIT_LIST_HEAD(&vm->userptr.invalidated);
> spin_lock_init(&vm->userptr.invalidated_lock);
>
> + INIT_LIST_HEAD(&vm->faults.list);
> + spin_lock_init(&vm->faults.lock);
> +
> ttm_lru_bulk_move_init(&vm->lru_bulk_move);
>
> INIT_WORK(&vm->destroy_work, vm_destroy_work_func);
> @@ -1808,6 +1894,8 @@ void xe_vm_close_and_put(struct xe_vm *vm)
> }
> up_write(&xe->usm.lock);
>
> + xe_vm_clear_fault_entries(vm);
> +
> for_each_tile(tile, xe, id)
> xe_range_fence_tree_fini(&vm->rftree[id]);
>
> diff --git a/drivers/gpu/drm/xe/xe_vm.h b/drivers/gpu/drm/xe/xe_vm.h
> index 361f10b3c453..e9f2de4189e0 100644
> --- a/drivers/gpu/drm/xe/xe_vm.h
> +++ b/drivers/gpu/drm/xe/xe_vm.h
> @@ -12,6 +12,12 @@
> #include "xe_map.h"
> #include "xe_vm_types.h"
>
> +/**
> + * MAX_FAULTS_SAVED_PER_VM - Maximum number of faults each vm can store
> before future
> + * faults are discarded to prevent memory overuse
> + */
> +#define MAX_FAULTS_SAVED_PER_VM 50
> +
> struct drm_device;
> struct drm_printer;
> struct drm_file;
> @@ -22,6 +28,7 @@ struct dma_fence;
>
> struct xe_exec_queue;
> struct xe_file;
> +struct xe_pagefault;
> struct xe_sync_entry;
> struct xe_svm_range;
> struct drm_exec;
> @@ -309,6 +316,8 @@ void xe_vm_snapshot_capture_delayed(struct xe_vm_snapshot
> *snap);
> void xe_vm_snapshot_print(struct xe_vm_snapshot *snap, struct drm_printer
> *p);
> void xe_vm_snapshot_free(struct xe_vm_snapshot *snap);
>
> +void xe_vm_add_fault_entry_pf(struct xe_vm *vm, struct xe_pagefault *pf);
> +
> /**
> * xe_vm_set_validating() - Register this task as currently making bos
> resident
> * @allow_res_evict: Allow eviction of buffer objects bound to @vm when
> diff --git a/drivers/gpu/drm/xe/xe_vm_types.h
> b/drivers/gpu/drm/xe/xe_vm_types.h
> index 3bf912bfbdcc..fff914fb0aa6 100644
> --- a/drivers/gpu/drm/xe/xe_vm_types.h
> +++ b/drivers/gpu/drm/xe/xe_vm_types.h
> @@ -20,6 +20,7 @@
> #include "xe_userptr.h"
>
> struct xe_bo;
> +struct xe_pagefault;
> struct xe_svm_range;
> struct xe_sync_entry;
> struct xe_user_fence;
> @@ -165,6 +166,24 @@ struct xe_userptr_vma {
>
> struct xe_device;
>
> +/**
> + * struct xe_vm_fault_entry - Elements of vm->faults.list
> + * @list: link into @xe_vm.faults.list
> + * @address: address of the fault
> + * @address_precision: precision of faulted address
> + * @access_type: type of address access that resulted in fault
> + * @fault_type: type of fault reported
> + * @fault_level: fault level of the fault
> + */
> +struct xe_vm_fault_entry {
> + struct list_head list;
> + u64 address;
> + u32 address_precision;
> + u8 access_type;
> + u8 fault_type;
> + u8 fault_level;
> +};
> +
> struct xe_vm {
> /** @gpuvm: base GPUVM used to track VMAs */
> struct drm_gpuvm gpuvm;
> @@ -302,6 +321,16 @@ struct xe_vm {
> bool capture_once;
> } error_capture;
>
> + /** @faults: List of all faults associated with this VM */
> + struct {
> + /** @faults.lock: lock protecting @faults.list */
> + spinlock_t lock;
> + /** @faults.list: list of xe_vm_fault_entry entries */
> + struct list_head list;
> + /** @faults.len: length of @faults.list */
> + unsigned int len;
> + } faults;
> +
> /**
> * @validation: Validation data only valid with the vm resv held.
> * Note: This is really task state of the task holding the vm resv,
> --
> 2.43.0
>
