diff options
Diffstat (limited to 'drivers/vfio/vfio.c')
| -rw-r--r-- | drivers/vfio/vfio.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 4cc961b894af..6fd6fa5469de 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -1729,6 +1729,60 @@ long vfio_external_check_extension(struct vfio_group *group, unsigned long arg) EXPORT_SYMBOL_GPL(vfio_external_check_extension); /** + * Sub-module support + */ +/* + * Helper for managing a buffer of info chain capabilities, allocate or + * reallocate a buffer with additional @size, filling in @id and @version + * of the capability. A pointer to the new capability is returned. + * + * NB. The chain is based at the head of the buffer, so new entries are + * added to the tail, vfio_info_cap_shift() should be called to fixup the + * next offsets prior to copying to the user buffer. + */ +struct vfio_info_cap_header *vfio_info_cap_add(struct vfio_info_cap *caps, + size_t size, u16 id, u16 version) +{ + void *buf; + struct vfio_info_cap_header *header, *tmp; + + buf = krealloc(caps->buf, caps->size + size, GFP_KERNEL); + if (!buf) { + kfree(caps->buf); + caps->size = 0; + return ERR_PTR(-ENOMEM); + } + + caps->buf = buf; + header = buf + caps->size; + + /* Eventually copied to user buffer, zero */ + memset(header, 0, size); + + header->id = id; + header->version = version; + + /* Add to the end of the capability chain */ + for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next) + ; /* nothing */ + + tmp->next = caps->size; + caps->size += size; + + return header; +} +EXPORT_SYMBOL_GPL(vfio_info_cap_add); + +void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset) +{ + struct vfio_info_cap_header *tmp; + + for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next - offset) + tmp->next += offset; +} +EXPORT_SYMBOL_GPL(vfio_info_cap_shift); + +/** * Module/class support */ static char *vfio_devnode(struct device *dev, umode_t *mode) |