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Commit d3df0a42 authored by Jérôme Glisse's avatar Jérôme Glisse Committed by Linus Torvalds
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mm/hmm: add new helper to hotplug CDM memory region 

Unlike unaddressable memory, coherent device memory has a real resource
associated with it on the system (as CPU can address it).  Add a new
helper to hotplug such memory within the HMM framework.

Link: http://lkml.kernel.org/r/20170817000548.32038-20-jglisse@redhat.com


Signed-off-by: default avatarJérôme Glisse <jglisse@redhat.com>
Reviewed-by: default avatarBalbir Singh <bsingharora@gmail.com>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Nellans <dnellans@nvidia.com>
Cc: Evgeny Baskakov <ebaskakov@nvidia.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mark Hairgrove <mhairgrove@nvidia.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: Sherry Cheung <SCheung@nvidia.com>
Cc: Subhash Gutti <sgutti@nvidia.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Bob Liu <liubo95@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent df6ad698

include/linux/hmm.h

+3 −0
Original line number Diff line number Diff line
@@ -443,6 +443,9 @@ struct hmm_devmem { 
struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,

				  struct device *device,

				  unsigned long size);

struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,

					   struct device *device,

					   struct resource *res);

void hmm_devmem_remove(struct hmm_devmem *devmem);



/*

mm/hmm.c

+83 −5
Original line number Diff line number Diff line
@@ -839,7 +839,11 @@ static void hmm_devmem_release(struct device *dev, void *data) 
	zone = page_zone(page);



	mem_hotplug_begin();

	if (resource->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY)

		__remove_pages(zone, start_pfn, npages);

	else

		arch_remove_memory(start_pfn << PAGE_SHIFT,

				   npages << PAGE_SHIFT);

	mem_hotplug_done();



	hmm_devmem_radix_release(resource);
@@ -875,7 +879,11 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem) 
	if (is_ram == REGION_INTERSECTS)

		return -ENXIO;



	if (devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY)

		devmem->pagemap.type = MEMORY_DEVICE_PUBLIC;

	else

		devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;



	devmem->pagemap.res = devmem->resource;

	devmem->pagemap.page_fault = hmm_devmem_fault;

	devmem->pagemap.page_free = hmm_devmem_free;
@@ -920,7 +928,13 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem) 
	 * over the device memory is un-accessible thus we do not want to

	 * create a linear mapping for the memory like arch_add_memory()

	 * would do.

	 *

	 * For device public memory, which is accesible by the CPU, we do

	 * want the linear mapping and thus use arch_add_memory().

	 */

	if (devmem->pagemap.type == MEMORY_DEVICE_PUBLIC)

		ret = arch_add_memory(nid, align_start, align_size, false);

	else

		ret = add_pages(nid, align_start >> PAGE_SHIFT,

				align_size >> PAGE_SHIFT, false);

	if (ret) {
@@ -1069,6 +1083,67 @@ struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops, 
}

EXPORT_SYMBOL(hmm_devmem_add);



struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,

					   struct device *device,

					   struct resource *res)

{

	struct hmm_devmem *devmem;

	int ret;



	if (res->desc != IORES_DESC_DEVICE_PUBLIC_MEMORY)

		return ERR_PTR(-EINVAL);



	static_branch_enable(&device_private_key);



	devmem = devres_alloc_node(&hmm_devmem_release, sizeof(*devmem),

				   GFP_KERNEL, dev_to_node(device));

	if (!devmem)

		return ERR_PTR(-ENOMEM);



	init_completion(&devmem->completion);

	devmem->pfn_first = -1UL;

	devmem->pfn_last = -1UL;

	devmem->resource = res;

	devmem->device = device;

	devmem->ops = ops;



	ret = percpu_ref_init(&devmem->ref, &hmm_devmem_ref_release,

			      0, GFP_KERNEL);

	if (ret)

		goto error_percpu_ref;



	ret = devm_add_action(device, hmm_devmem_ref_exit, &devmem->ref);

	if (ret)

		goto error_devm_add_action;





	devmem->pfn_first = devmem->resource->start >> PAGE_SHIFT;

	devmem->pfn_last = devmem->pfn_first +

			   (resource_size(devmem->resource) >> PAGE_SHIFT);



	ret = hmm_devmem_pages_create(devmem);

	if (ret)

		goto error_devm_add_action;



	devres_add(device, devmem);



	ret = devm_add_action(device, hmm_devmem_ref_kill, &devmem->ref);

	if (ret) {

		hmm_devmem_remove(devmem);

		return ERR_PTR(ret);

	}



	return devmem;



error_devm_add_action:

	hmm_devmem_ref_kill(&devmem->ref);

	hmm_devmem_ref_exit(&devmem->ref);

error_percpu_ref:

	devres_free(devmem);

	return ERR_PTR(ret);

}

EXPORT_SYMBOL(hmm_devmem_add_resource);



/*

 * hmm_devmem_remove() - remove device memory (kill and free ZONE_DEVICE)

 *
@@ -1082,6 +1157,7 @@ void hmm_devmem_remove(struct hmm_devmem *devmem) 
{

	resource_size_t start, size;

	struct device *device;

	bool cdm = false;



	if (!devmem)

		return;
@@ -1090,10 +1166,12 @@ void hmm_devmem_remove(struct hmm_devmem *devmem) 
	start = devmem->resource->start;

	size = resource_size(devmem->resource);



	cdm = devmem->resource->desc == IORES_DESC_DEVICE_PUBLIC_MEMORY;

	hmm_devmem_ref_kill(&devmem->ref);

	hmm_devmem_ref_exit(&devmem->ref);

	hmm_devmem_pages_remove(devmem);



	if (!cdm)

		devm_release_mem_region(device, start, size);

}

EXPORT_SYMBOL(hmm_devmem_remove);