6.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Hellström thomas.hellstrom@linux.intel.com
commit eb5723a75104605b7d2207a7d598e314166fbef4 upstream.
When the xe pm_notifier evicts for suspend / hibernate, there might be racing tasks trying to re-validate again. This can lead to suspend taking excessive time or get stuck in a live-lock. This behaviour becomes much worse with the fix that actually makes re-validation bring back bos to VRAM rather than letting them remain in TT.
Prevent that by having exec and the rebind worker waiting for a completion that is set to block by the pm_notifier before suspend and is signaled by the pm_notifier after resume / wakeup.
It's probably still possible to craft malicious applications that block suspending. More work is pending to fix that.
v3: - Avoid wait_for_completion() in the kernel worker since it could potentially cause work item flushes from freezable processes to wait forever. Instead terminate the rebind workers if needed and re-launch at resume. (Matt Auld) v4: - Fix some bad naming and leftover debug printouts. - Fix kerneldoc. - Use drmm_mutex_init() for the xe->rebind_resume_lock (Matt Auld). - Rework the interface of xe_vm_rebind_resume_worker (Matt Auld).
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4288 Fixes: c6a4d46ec1d7 ("drm/xe: evict user memory in PM notifier") Cc: Matthew Auld matthew.auld@intel.com Cc: Rodrigo Vivi rodrigo.vivi@intel.com Cc: stable@vger.kernel.org # v6.16+ Signed-off-by: Thomas Hellström thomas.hellstrom@linux.intel.com Reviewed-by: Matthew Auld matthew.auld@intel.com Link: https://lore.kernel.org/r/20250904160715.2613-4-thomas.hellstrom@linux.intel... (cherry picked from commit 599334572a5a99111015fbbd5152ce4dedc2f8b7) Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/xe/xe_device_types.h | 6 +++++ drivers/gpu/drm/xe/xe_exec.c | 9 +++++++ drivers/gpu/drm/xe/xe_pm.c | 25 ++++++++++++++++++++ drivers/gpu/drm/xe/xe_vm.c | 42 ++++++++++++++++++++++++++++++++++- drivers/gpu/drm/xe/xe_vm.h | 2 + drivers/gpu/drm/xe/xe_vm_types.h | 5 ++++ 6 files changed, 88 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/xe/xe_device_types.h +++ b/drivers/gpu/drm/xe/xe_device_types.h @@ -529,6 +529,12 @@ struct xe_device {
/** @pm_notifier: Our PM notifier to perform actions in response to various PM events. */ struct notifier_block pm_notifier; + /** @pm_block: Completion to block validating tasks on suspend / hibernate prepare */ + struct completion pm_block; + /** @rebind_resume_list: List of wq items to kick on resume. */ + struct list_head rebind_resume_list; + /** @rebind_resume_lock: Lock to protect the rebind_resume_list */ + struct mutex rebind_resume_lock;
/** @pmt: Support the PMT driver callback interface */ struct { --- a/drivers/gpu/drm/xe/xe_exec.c +++ b/drivers/gpu/drm/xe/xe_exec.c @@ -237,6 +237,15 @@ retry: goto err_unlock_list; }
+ /* + * It's OK to block interruptible here with the vm lock held, since + * on task freezing during suspend / hibernate, the call will + * return -ERESTARTSYS and the IOCTL will be rerun. + */ + err = wait_for_completion_interruptible(&xe->pm_block); + if (err) + goto err_unlock_list; + vm_exec.vm = &vm->gpuvm; vm_exec.flags = DRM_EXEC_INTERRUPTIBLE_WAIT; if (xe_vm_in_lr_mode(vm)) { --- a/drivers/gpu/drm/xe/xe_pm.c +++ b/drivers/gpu/drm/xe/xe_pm.c @@ -23,6 +23,7 @@ #include "xe_pcode.h" #include "xe_pxp.h" #include "xe_trace.h" +#include "xe_vm.h" #include "xe_wa.h"
/** @@ -285,6 +286,19 @@ static u32 vram_threshold_value(struct x return DEFAULT_VRAM_THRESHOLD; }
+static void xe_pm_wake_rebind_workers(struct xe_device *xe) +{ + struct xe_vm *vm, *next; + + mutex_lock(&xe->rebind_resume_lock); + list_for_each_entry_safe(vm, next, &xe->rebind_resume_list, + preempt.pm_activate_link) { + list_del_init(&vm->preempt.pm_activate_link); + xe_vm_resume_rebind_worker(vm); + } + mutex_unlock(&xe->rebind_resume_lock); +} + static int xe_pm_notifier_callback(struct notifier_block *nb, unsigned long action, void *data) { @@ -294,6 +308,7 @@ static int xe_pm_notifier_callback(struc switch (action) { case PM_HIBERNATION_PREPARE: case PM_SUSPEND_PREPARE: + reinit_completion(&xe->pm_block); xe_pm_runtime_get(xe); err = xe_bo_evict_all_user(xe); if (err) @@ -310,6 +325,8 @@ static int xe_pm_notifier_callback(struc break; case PM_POST_HIBERNATION: case PM_POST_SUSPEND: + complete_all(&xe->pm_block); + xe_pm_wake_rebind_workers(xe); xe_bo_notifier_unprepare_all_pinned(xe); xe_pm_runtime_put(xe); break; @@ -336,6 +353,14 @@ int xe_pm_init(struct xe_device *xe) if (err) return err;
+ err = drmm_mutex_init(&xe->drm, &xe->rebind_resume_lock); + if (err) + goto err_unregister; + + init_completion(&xe->pm_block); + complete_all(&xe->pm_block); + INIT_LIST_HEAD(&xe->rebind_resume_list); + /* For now suspend/resume is only allowed with GuC */ if (!xe_device_uc_enabled(xe)) return 0; --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -393,6 +393,9 @@ static int xe_gpuvm_validate(struct drm_ list_move_tail(&gpuva_to_vma(gpuva)->combined_links.rebind, &vm->rebind_list);
+ if (!try_wait_for_completion(&vm->xe->pm_block)) + return -EAGAIN; + ret = xe_bo_validate(gem_to_xe_bo(vm_bo->obj), vm, false); if (ret) return ret; @@ -479,6 +482,33 @@ static int xe_preempt_work_begin(struct return xe_vm_validate_rebind(vm, exec, vm->preempt.num_exec_queues); }
+static bool vm_suspend_rebind_worker(struct xe_vm *vm) +{ + struct xe_device *xe = vm->xe; + bool ret = false; + + mutex_lock(&xe->rebind_resume_lock); + if (!try_wait_for_completion(&vm->xe->pm_block)) { + ret = true; + list_move_tail(&vm->preempt.pm_activate_link, &xe->rebind_resume_list); + } + mutex_unlock(&xe->rebind_resume_lock); + + return ret; +} + +/** + * xe_vm_resume_rebind_worker() - Resume the rebind worker. + * @vm: The vm whose preempt worker to resume. + * + * Resume a preempt worker that was previously suspended by + * vm_suspend_rebind_worker(). + */ +void xe_vm_resume_rebind_worker(struct xe_vm *vm) +{ + queue_work(vm->xe->ordered_wq, &vm->preempt.rebind_work); +} + static void preempt_rebind_work_func(struct work_struct *w) { struct xe_vm *vm = container_of(w, struct xe_vm, preempt.rebind_work); @@ -502,6 +532,11 @@ static void preempt_rebind_work_func(str }
retry: + if (!try_wait_for_completion(&vm->xe->pm_block) && vm_suspend_rebind_worker(vm)) { + up_write(&vm->lock); + return; + } + if (xe_vm_userptr_check_repin(vm)) { err = xe_vm_userptr_pin(vm); if (err) @@ -1686,6 +1721,7 @@ struct xe_vm *xe_vm_create(struct xe_dev if (flags & XE_VM_FLAG_LR_MODE) { INIT_WORK(&vm->preempt.rebind_work, preempt_rebind_work_func); xe_pm_runtime_get_noresume(xe); + INIT_LIST_HEAD(&vm->preempt.pm_activate_link); }
if (flags & XE_VM_FLAG_FAULT_MODE) { @@ -1867,8 +1903,12 @@ void xe_vm_close_and_put(struct xe_vm *v xe_assert(xe, !vm->preempt.num_exec_queues);
xe_vm_close(vm); - if (xe_vm_in_preempt_fence_mode(vm)) + if (xe_vm_in_preempt_fence_mode(vm)) { + mutex_lock(&xe->rebind_resume_lock); + list_del_init(&vm->preempt.pm_activate_link); + mutex_unlock(&xe->rebind_resume_lock); flush_work(&vm->preempt.rebind_work); + } if (xe_vm_in_fault_mode(vm)) xe_svm_close(vm);
--- a/drivers/gpu/drm/xe/xe_vm.h +++ b/drivers/gpu/drm/xe/xe_vm.h @@ -268,6 +268,8 @@ struct dma_fence *xe_vm_bind_kernel_bo(s struct xe_exec_queue *q, u64 addr, enum xe_cache_level cache_lvl);
+void xe_vm_resume_rebind_worker(struct xe_vm *vm); + /** * xe_vm_resv() - Return's the vm's reservation object * @vm: The vm --- a/drivers/gpu/drm/xe/xe_vm_types.h +++ b/drivers/gpu/drm/xe/xe_vm_types.h @@ -286,6 +286,11 @@ struct xe_vm { * BOs */ struct work_struct rebind_work; + /** + * @preempt.pm_activate_link: Link to list of rebind workers to be + * kicked on resume. + */ + struct list_head pm_activate_link; } preempt;
/** @um: unified memory state */