This introduce a dummy HMM device class so device driver can use it to create hmm_device for the sole purpose of registering device memory. It is usefull to device driver that want to manage multiple physical device memory under same device umbrella.
Signed-off-by: Jérôme Glisse <jgli...@redhat.com> Signed-off-by: Jatin Kumar <jaku...@nvidia.com> Signed-off-by: John Hubbard <jhubb...@nvidia.com> Signed-off-by: Mark Hairgrove <mhairgr...@nvidia.com> Signed-off-by: Sherry Cheung <sche...@nvidia.com> Signed-off-by: Subhash Gutti <sgu...@nvidia.com> --- include/linux/hmm.h | 22 ++++++++++++- mm/hmm.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 116 insertions(+), 1 deletion(-) diff --git a/include/linux/hmm.h b/include/linux/hmm.h index ac0b69a..106de1f 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -88,10 +88,10 @@ #if IS_ENABLED(CONFIG_HMM) +#include <linux/device.h> #include <linux/memremap.h> #include <linux/completion.h> - struct hmm; /* @@ -484,6 +484,26 @@ static inline unsigned long hmm_devmem_page_get_drvdata(struct page *page) } +/* + * struct hmm_device - fake device to hang device memory onto + * + * @device: device struct + * @minor: device minor number + */ +struct hmm_device { + struct device device; + unsigned minor; +}; + +/* + * Device driver that want to handle multiple devices memory through a single + * fake device can use hmm_device to do so. This is purely an helper and it + * is not needed to make use of any HMM functionality. + */ +struct hmm_device *hmm_device_new(void); +void hmm_device_put(struct hmm_device *hmm_device); + + /* Below are for HMM internal use only ! Not to be use by device driver ! */ void hmm_mm_destroy(struct mm_struct *mm); diff --git a/mm/hmm.c b/mm/hmm.c index f2ca895..61c3640187 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -24,6 +24,7 @@ #include <linux/slab.h> #include <linux/sched.h> #include <linux/mmzone.h> +#include <linux/module.h> #include <linux/pagemap.h> #include <linux/swapops.h> #include <linux/hugetlb.h> @@ -1078,3 +1079,97 @@ int hmm_devmem_fault_range(struct hmm_devmem *devmem, return 0; } EXPORT_SYMBOL(hmm_devmem_fault_range); + +/* + * Device driver that want to handle multiple devices memory through a single + * fake device can use hmm_device to do so. This is purely an helper and it + * is not needed to make use of any HMM functionality. + */ +#define HMM_DEVICE_MAX 256 + +static DECLARE_BITMAP(hmm_device_mask, HMM_DEVICE_MAX); +static DEFINE_SPINLOCK(hmm_device_lock); +static struct class *hmm_device_class; +static dev_t hmm_device_devt; + +static void hmm_device_release(struct device *device) +{ + struct hmm_device *hmm_device; + + hmm_device = container_of(device, struct hmm_device, device); + spin_lock(&hmm_device_lock); + clear_bit(hmm_device->minor, hmm_device_mask); + spin_unlock(&hmm_device_lock); + + kfree(hmm_device); +} + +struct hmm_device *hmm_device_new(void) +{ + struct hmm_device *hmm_device; + int ret; + + hmm_device = kzalloc(sizeof(*hmm_device), GFP_KERNEL); + if (!hmm_device) + return ERR_PTR(-ENOMEM); + + ret = alloc_chrdev_region(&hmm_device->device.devt,0,1,"hmm_device"); + if (ret < 0) { + kfree(hmm_device); + return NULL; + } + + spin_lock(&hmm_device_lock); + hmm_device->minor=find_first_zero_bit(hmm_device_mask,HMM_DEVICE_MAX); + if (hmm_device->minor >= HMM_DEVICE_MAX) { + spin_unlock(&hmm_device_lock); + kfree(hmm_device); + return NULL; + } + set_bit(hmm_device->minor, hmm_device_mask); + spin_unlock(&hmm_device_lock); + + dev_set_name(&hmm_device->device, "hmm_device%d", hmm_device->minor); + hmm_device->device.devt = MKDEV(MAJOR(hmm_device_devt), + hmm_device->minor); + hmm_device->device.release = hmm_device_release; + hmm_device->device.class = hmm_device_class; + device_initialize(&hmm_device->device); + + return hmm_device; +} +EXPORT_SYMBOL(hmm_device_new); + +void hmm_device_put(struct hmm_device *hmm_device) +{ + put_device(&hmm_device->device); +} +EXPORT_SYMBOL(hmm_device_put); + +static int __init hmm_init(void) +{ + int ret; + + ret = alloc_chrdev_region(&hmm_device_devt, 0, + HMM_DEVICE_MAX, + "hmm_device"); + if (ret) + return ret; + + hmm_device_class = class_create(THIS_MODULE, "hmm_device"); + if (IS_ERR(hmm_device_class)) { + unregister_chrdev_region(hmm_device_devt, HMM_DEVICE_MAX); + return PTR_ERR(hmm_device_class); + } + return 0; +} + +static void __exit hmm_exit(void) +{ + unregister_chrdev_region(hmm_device_devt, HMM_DEVICE_MAX); + class_destroy(hmm_device_class); +} + +module_init(hmm_init); +module_exit(hmm_exit); +MODULE_LICENSE("GPL"); -- 2.4.3