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Subject[HMM-v25 19/19] mm/hmm: add new helper to hotplug CDM memory region v3
Date
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.

Changed since v2:
- s/host/public
Changed since v1:
- s/public/host

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
---
include/linux/hmm.h | 3 ++
mm/hmm.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 86 insertions(+), 5 deletions(-)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 79e63178fd87..5866f3194c26 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -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);

/*
diff --git a/mm/hmm.c b/mm/hmm.c
index 1a1e79d390c1..3faa4d40295e 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -854,7 +854,11 @@ static void hmm_devmem_release(struct device *dev, void *data)
zone = page_zone(page);

mem_hotplug_begin();
- __remove_pages(zone, start_pfn, npages);
+ 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);
@@ -890,7 +894,11 @@ static int hmm_devmem_pages_create(struct hmm_devmem *devmem)
if (is_ram == REGION_INTERSECTS)
return -ENXIO;

- devmem->pagemap.type = MEMORY_DEVICE_PRIVATE;
+ 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;
@@ -935,9 +943,15 @@ 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().
*/
- ret = add_pages(nid, align_start >> PAGE_SHIFT,
- align_size >> PAGE_SHIFT, false);
+ 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) {
mem_hotplug_done();
goto error_add_memory;
@@ -1084,6 +1098,67 @@ 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)
*
@@ -1097,6 +1172,7 @@ void hmm_devmem_remove(struct hmm_devmem *devmem)
{
resource_size_t start, size;
struct device *device;
+ bool cdm = false;

if (!devmem)
return;
@@ -1105,11 +1181,13 @@ 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);

- devm_release_mem_region(device, start, size);
+ if (!cdm)
+ devm_release_mem_region(device, start, size);
}
EXPORT_SYMBOL(hmm_devmem_remove);

--
2.13.4
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