Re: [PATCH v5 7/9] drm/xe/exec_queue: Introduce xe_exec_queue_reinit()

[Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>]

On 4/15/2026 9:10 AM, Daniele Ceraolo Spurio wrote:
>
>
> On 4/6/2026 7:07 AM, Raag Jadav wrote:
>> In preparation of usecases which require re-initializing an exec queue
>> after PCIe FLR, introduce xe_exec_queue_reinit() helper. All the exec
>> queue LCRs already exist but the context is lost on PCIe FLR and needs
>> re-initialization.
>
> Isn't this potentially problematic for userspace? If they have state 
> saved in their LRCs, that state would be lost without any way for the 
> user to know. New submission on those contexts might end up giving 
> incorrect output without explanation.
> IMO it'd be better to just kill all the contexts and be done with it. 
> FLR is a full reset and I don't think apps are supposed to survive it 
> without noticing.

Just realized looking at the follow up patches that this is only called 
for the migration queue, which is kernel-owned. If we're only expecting 
to re-init kernel queues that needs to be documented and we need an 
assert in code.

>
> Daniele
>
>>
>> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
>> ---
>> v2: Re-initialize migrate context (Matthew Brost)
>> ---
>>   drivers/gpu/drm/xe/xe_exec_queue.c | 37 ++++++++++++++++++++++++++----
>>   drivers/gpu/drm/xe/xe_exec_queue.h |  1 +
>>   drivers/gpu/drm/xe/xe_lrc.c        | 17 ++++++++++++++
>>   drivers/gpu/drm/xe/xe_lrc.h        |  2 ++
>>   4 files changed, 53 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c 
>> b/drivers/gpu/drm/xe/xe_exec_queue.c
>> index b287d0e0e60a..dd99bf766926 100644
>> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
>> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
>> @@ -331,9 +331,8 @@ static void __xe_exec_queue_fini(struct 
>> xe_exec_queue *q)
>>           xe_lrc_put(q->lrc[i]);
>>   }
>>   -static int __xe_exec_queue_init(struct xe_exec_queue *q, u32 
>> exec_queue_flags)
>> +static u32 xe_lrc_init_flags(struct xe_exec_queue *q, u32 
>> exec_queue_flags)
>>   {
>> -    int i, err;
>>       u32 flags = 0;
>>         /*
>> @@ -356,6 +355,13 @@ static int __xe_exec_queue_init(struct 
>> xe_exec_queue *q, u32 exec_queue_flags)
>>       if (q->flags & EXEC_QUEUE_FLAG_DISABLE_STATE_CACHE_PERF_FIX)
>>           flags |= XE_LRC_DISABLE_STATE_CACHE_PERF_FIX;
>>   +    return flags;
>> +}
>> +
>> +static int __xe_exec_queue_init(struct xe_exec_queue *q, u32 
>> exec_queue_flags)
>> +{
>> +    int i, err;
>> +
>>       err = q->ops->init(q);
>>       if (err)
>>           return err;
>> @@ -379,8 +385,8 @@ static int __xe_exec_queue_init(struct 
>> xe_exec_queue *q, u32 exec_queue_flags)
>>                 marker = xe_gt_sriov_vf_wait_valid_ggtt(q->gt);
>>   -            lrc = xe_lrc_create(q->hwe, q->vm, q->replay_state,
>> -                        xe_lrc_ring_size(), q->msix_vec, flags);
>> +            lrc = xe_lrc_create(q->hwe, q->vm, q->replay_state, 
>> xe_lrc_ring_size(),
>> +                        q->msix_vec, xe_lrc_init_flags(q, 
>> exec_queue_flags));
>>               if (IS_ERR(lrc)) {
>>                   err = PTR_ERR(lrc);
>>                   goto err_lrc;
>> @@ -402,6 +408,29 @@ static int __xe_exec_queue_init(struct 
>> xe_exec_queue *q, u32 exec_queue_flags)
>>       return err;
>>   }
>>   +/**
>> + * xe_exec_queue_reinit() - Re-initialize exec queue
>> + * @q: exec queue to re-initialize
>> + *
>> + * Returns: 0 on success, negative error code otherwise.
>> + */
>> +int xe_exec_queue_reinit(struct xe_exec_queue *q)
>> +{
>> +    int i, err;
>> +
>> +    /* Re-initialize submission backend */
>> +    q->ops->reinit(q);
>> +
>> +    for (i = 0; i < q->width; i++) {
>> +        err = xe_lrc_reinit(q->lrc[i], q->hwe, q->vm, q->replay_state,
>> +                    q->msix_vec, xe_lrc_init_flags(q, q->flags));
>> +        if (err)
>> +            return err;
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>   /**
>>    * xe_exec_queue_create() - Create an exec queue
>>    * @xe: Xe device
>> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.h 
>> b/drivers/gpu/drm/xe/xe_exec_queue.h
>> index a82d99bd77bc..445867d4da26 100644
>> --- a/drivers/gpu/drm/xe/xe_exec_queue.h
>> +++ b/drivers/gpu/drm/xe/xe_exec_queue.h
>> @@ -34,6 +34,7 @@ struct xe_exec_queue 
>> *xe_exec_queue_create_bind(struct xe_device *xe,
>>   void xe_exec_queue_fini(struct xe_exec_queue *q);
>>   void xe_exec_queue_destroy(struct kref *ref);
>>   void xe_exec_queue_assign_name(struct xe_exec_queue *q, u32 instance);
>> +int xe_exec_queue_reinit(struct xe_exec_queue *q);
>>     static inline struct xe_exec_queue *
>>   xe_exec_queue_get_unless_zero(struct xe_exec_queue *q)
>> diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
>> index 9d12a0d2f0b5..a6421ac3765b 100644
>> --- a/drivers/gpu/drm/xe/xe_lrc.c
>> +++ b/drivers/gpu/drm/xe/xe_lrc.c
>> @@ -1593,6 +1593,23 @@ static int xe_lrc_ctx_init(struct xe_lrc *lrc, 
>> struct xe_hw_engine *hwe, struct
>>       return err;
>>   }
>>   +/**
>> + * xe_lrc_reinit() - Re-initialize LRC
>> + * @lrc: Pointer to the LRC
>> + * @hwe: Hardware Engine
>> + * @vm: The VM (address space)
>> + * @replay_state: GPU hang replay state
>> + * @msix_vec: MSI-X interrupt vector (for platforms that support it)
>> + * @init_flags: LRC initialization flags
>> + *
>> + * Returns: 0 on success, negative error code otherwise.
>> + */
>> +int xe_lrc_reinit(struct xe_lrc *lrc, struct xe_hw_engine *hwe, 
>> struct xe_vm *vm,
>> +          void *replay_state, u16 msix_vec, u32 init_flags)
>> +{
>> +    return xe_lrc_ctx_init(lrc, hwe, vm, replay_state, msix_vec, 
>> init_flags);
>> +}
>> +
>>   static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine 
>> *hwe, struct xe_vm *vm,
>>                  void *replay_state, u32 ring_size, u16 msix_vec, u32 
>> init_flags)
>>   {
>> diff --git a/drivers/gpu/drm/xe/xe_lrc.h b/drivers/gpu/drm/xe/xe_lrc.h
>> index e7c975f9e2d9..514355ce3d6a 100644
>> --- a/drivers/gpu/drm/xe/xe_lrc.h
>> +++ b/drivers/gpu/drm/xe/xe_lrc.h
>> @@ -53,6 +53,8 @@ struct xe_lrc_snapshot {
>>     struct xe_lrc *xe_lrc_create(struct xe_hw_engine *hwe, struct 
>> xe_vm *vm,
>>                    void *replay_state, u32 ring_size, u16 msix_vec, 
>> u32 flags);
>> +int xe_lrc_reinit(struct xe_lrc *lrc, struct xe_hw_engine *hwe, 
>> struct xe_vm *vm,
>> +          void *replay_state, u16 msix_vec, u32 init_flags);
>>   void xe_lrc_destroy(struct kref *ref);
>>     /**
>