Unverified Commit eb5723a7 authored by Thomas Hellström's avatar Thomas Hellström Committed by Rodrigo Vivi
Browse files

drm/xe: Block exec and rebind worker while evicting for suspend / hibernate 

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: c6a4d46e ("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: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://lore.kernel.org/r/20250904160715.2613-4-thomas.hellstrom@linux.intel.com


(cherry picked from commit 59933457)
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent d8482030

drivers/gpu/drm/xe/xe_device_types.h

+6 −0
Original line number Diff line number Diff line
@@ -553,6 +553,12 @@ 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 {

drivers/gpu/drm/xe/xe_exec.c

+9 −0
Original line number Diff line number Diff line
@@ -237,6 +237,15 @@ int xe_exec_ioctl(struct drm_device *dev, void *data, struct drm_file *file) 
		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)) {

drivers/gpu/drm/xe/xe_pm.c

+25 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include "xe_pcode.h"

#include "xe_pxp.h"

#include "xe_trace.h"

#include "xe_vm.h"

#include "xe_wa.h"



/**
@@ -290,6 +291,19 @@ static u32 vram_threshold_value(struct xe_device *xe) 
	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)

{
@@ -299,6 +313,7 @@ static int xe_pm_notifier_callback(struct notifier_block *nb, 
	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)
@@ -315,6 +330,8 @@ static int xe_pm_notifier_callback(struct notifier_block *nb, 
		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;
@@ -341,6 +358,14 @@ 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;

drivers/gpu/drm/xe/xe_vm.c

+41 −1
Original line number Diff line number Diff line
@@ -393,6 +393,9 @@ static int xe_gpuvm_validate(struct drm_gpuvm_bo *vm_bo, struct drm_exec *exec) 
		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 drm_exec *exec, struct xe_vm *vm, 
	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(struct work_struct *w) 
	}



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)
@@ -1714,6 +1749,7 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32 flags, struct xe_file *xef) 
	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) {
@@ -1895,8 +1931,12 @@ void xe_vm_close_and_put(struct xe_vm *vm) 
	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);

drivers/gpu/drm/xe/xe_vm.h

+2 −0
Original line number Diff line number Diff line
@@ -273,6 +273,8 @@ struct dma_fence *xe_vm_bind_kernel_bo(struct xe_vm *vm, struct xe_bo *bo, 
				       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