Re: [PATCH 5.4.y] s390/virtio_ccw: Don't allocate/assign airqs for non-existing queues

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: 2ccd42b959aaf490333dbd3b9b102eaf295c036a

Status in newer kernel trees:
6.14.y | Present (different SHA1: fc90e2379125)
6.12.y | Present (different SHA1: f268ee2fbb53)
6.6.y | Present (different SHA1: 3867566eb8a4)
6.1.y | Present (different SHA1: 355715264917)
5.15.y | Not found
5.10.y | Not found

Note: The patch differs from the upstream commit:
---
1:  2ccd42b959aaf ! 1:  8e0e5446dde75 s390/virtio_ccw: Don't allocate/assign airqs for non-existing queues
    @@ Commit message
         Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
         Link: https://lore.kernel.org/r/20250402203621.940090-1-david@redhat.com
         Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
    +    (cherry picked from commit 2ccd42b959aaf490333dbd3b9b102eaf295c036a)
    +    Signed-off-by: David Hildenbrand <david@redhat.com>
     
      ## drivers/s390/virtio/virtio_ccw.c ##
     @@ drivers/s390/virtio/virtio_ccw.c: static struct airq_info *new_airq_info(int index)
    - static unsigned long *get_airq_indicator(struct virtqueue *vqs[], int nvqs,
    - 					 u64 *first, void **airq_info)
    + static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,
    + 					u64 *first, void **airq_info)
      {
     -	int i, j;
     +	int i, j, queue_idx, highest_queue_idx = -1;
      	struct airq_info *info;
    - 	unsigned long *indicator_addr = NULL;
    + 	unsigned long indicator_addr = 0;
      	unsigned long bit, flags;
      
     +	/* Array entries without an actual queue pointer must be ignored. */
    @@ drivers/s390/virtio/virtio_ccw.c: static struct airq_info *new_airq_info(int ind
      	for (i = 0; i < MAX_AIRQ_AREAS && !indicator_addr; i++) {
      		mutex_lock(&airq_areas_lock);
      		if (!airq_areas[i])
    -@@ drivers/s390/virtio/virtio_ccw.c: static unsigned long *get_airq_indicator(struct virtqueue *vqs[], int nvqs,
    +@@ drivers/s390/virtio/virtio_ccw.c: static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,
      		if (!info)
    - 			return NULL;
    + 			return 0;
      		write_lock_irqsave(&info->lock, flags);
     -		bit = airq_iv_alloc(info->aiv, nvqs);
     +		bit = airq_iv_alloc(info->aiv, highest_queue_idx + 1);
      		if (bit == -1UL) {
      			/* Not enough vacancies. */
      			write_unlock_irqrestore(&info->lock, flags);
    -@@ drivers/s390/virtio/virtio_ccw.c: static unsigned long *get_airq_indicator(struct virtqueue *vqs[], int nvqs,
    +@@ drivers/s390/virtio/virtio_ccw.c: static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,
      		*first = bit;
      		*airq_info = info;
    - 		indicator_addr = info->aiv->vector;
    + 		indicator_addr = (unsigned long)info->aiv->vector;
     -		for (j = 0; j < nvqs; j++) {
     -			airq_iv_set_ptr(info->aiv, bit + j,
     +		for (j = 0, queue_idx = 0; j < nvqs; j++) {
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.4.y        |  Success    |  Success   |