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mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory

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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 useful to device driver that want to manage multiple physical device
memory under same struct device umbrella.

Link: http://lkml.kernel.org/r/20170817000548.32038-13-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Evgeny Baskakov <ebaskakov@nvidia.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Mark Hairgrove <mhairgrove@nvidia.com>
Signed-off-by: Sherry Cheung <SCheung@nvidia.com>
Signed-off-by: Subhash Gutti <sgutti@nvidia.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jérôme Glisse 2017-09-08 16:12:02 -07:00 committed by Linus Torvalds
parent 4ef589dc9b
commit 858b54dabf
2 changed files with 102 additions and 1 deletions
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22
include/linux/hmm.h
View file

@ -72,11 +72,11 @@
#if IS_ENABLED(CONFIG_HMM)
#include <linux/device.h>
#include <linux/migrate.h>
#include <linux/memremap.h>
#include <linux/completion.h>
struct hmm;
/*
@ -474,6 +474,26 @@ static inline unsigned long hmm_devmem_page_get_drvdata(struct page *page)
return drvdata[1];
}
/*
* struct hmm_device - fake device to hang device memory onto
*
* @device: device struct
* @minor: device minor number
*/
struct hmm_device {
struct device device;
unsigned int minor;
};
/*
* A device driver that wants to handle multiple devices memory through a
* single fake device can use hmm_device to do so. This is purely a helper and
* it is not strictly needed, in order to make use of any HMM functionality.
*/
struct hmm_device *hmm_device_new(void *drvdata);
void hmm_device_put(struct hmm_device *hmm_device);
#endif /* IS_ENABLED(CONFIG_DEVICE_PRIVATE) */

81
mm/hmm.c
View file

@ -19,6 +19,7 @@
*/
#include <linux/mm.h>
#include <linux/hmm.h>
#include <linux/init.h>
#include <linux/rmap.h>
#include <linux/swap.h>
#include <linux/slab.h>
@ -1096,4 +1097,84 @@ void hmm_devmem_remove(struct hmm_devmem *devmem)
devm_release_mem_region(device, start, size);
}
EXPORT_SYMBOL(hmm_devmem_remove);
/*
* A device driver that wants to handle multiple devices memory through a
* single fake device can use hmm_device to do so. This is purely a 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 *drvdata)
{
struct hmm_device *hmm_device;
hmm_device = kzalloc(sizeof(*hmm_device), GFP_KERNEL);
if (!hmm_device)
return ERR_PTR(-ENOMEM);
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 ERR_PTR(-EBUSY);
}
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;
dev_set_drvdata(&hmm_device->device, drvdata);
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;
}
device_initcall(hmm_init);
#endif /* IS_ENABLED(CONFIG_DEVICE_PRIVATE) */