Re: [PATCH v2 3/4] dax: Update hmem resource/device registration

Fontenot, Nathan
2025-01-21T18:49:28Z

On 1/16/2025 4:28 PM, Ira Weiny wrote:
> Nathan Fontenot wrote:
>> In order to handle registering hmem devices for SOFT RESERVE reources
> ^^^^^^^^^
> resources
>
>> that are added late in boot update the hmem_register_resource(),
>> hmem_register_device(), and walk_hmem_resources() interfaces.
>>
>> Remove the target_nid arg to hmem_register_resource(). The target nid
>> value is calculated from the resource start address and not used until
>> registering a device for the resource. Move the target nid calculation
>> to hmem_register_device().
>>
>> To allow for registering hmem devices outside of the hmem dax driver
>> probe routine save the dax hmem platform driver during probe. The
>> hmem_register_device() interface can then drop the host and target
>> nid parameters.
>>
>> There should be no functional changes.
>>
>> Signed-off-by: Nathan Fontenot <nathan.fontenot@amd.com>
>> ---
>> drivers/acpi/numa/hmat.c | 7 ++-----
>> drivers/dax/hmem/device.c | 14 ++++++--------
>> drivers/dax/hmem/hmem.c | 12 ++++++++----
>> include/linux/dax.h | 9 ++++-----
>> 4 files changed, 20 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c
>> index 1a902a02390f..23d4b3ad6d88 100644
>> --- a/drivers/acpi/numa/hmat.c
>> +++ b/drivers/acpi/numa/hmat.c
>> @@ -857,11 +857,8 @@ static void hmat_register_target_devices(struct memory_target *target)
>> if (!IS_ENABLED(CONFIG_DEV_DAX_HMEM))
>> return;
>>
>> - for (res = target->memregions.child; res; res = res->sibling) {
>> - int target_nid = pxm_to_node(target->memory_pxm);
>> -
>> - hmem_register_resource(target_nid, res);
>> - }
>> + for (res = target->memregions.child; res; res = res->sibling)
>> + hmem_register_resource(res);
>> }
>>
>> static void hmat_register_target(struct memory_target *target)
>> diff --git a/drivers/dax/hmem/device.c b/drivers/dax/hmem/device.c
>> index f9e1a76a04a9..ae25e08a636f 100644
>> --- a/drivers/dax/hmem/device.c
>> +++ b/drivers/dax/hmem/device.c
>> @@ -17,14 +17,14 @@ static struct resource hmem_active = {
>> .flags = IORESOURCE_MEM,
>> };
>>
>> -int walk_hmem_resources(struct device *host, walk_hmem_fn fn)
>> +int walk_hmem_resources(walk_hmem_fn fn)
>> {
>> struct resource *res;
>> int rc = 0;
>>
>> mutex_lock(&hmem_resource_lock);
>> for (res = hmem_active.child; res; res = res->sibling) {
>> - rc = fn(host, (int) res->desc, res);
>> + rc = fn(res);
>> if (rc)
>> break;
>> }
>> @@ -33,7 +33,7 @@ int walk_hmem_resources(struct device *host, walk_hmem_fn fn)
>> }
>> EXPORT_SYMBOL_GPL(walk_hmem_resources);
>>
>> -static void __hmem_register_resource(int target_nid, struct resource *res)
>> +static void __hmem_register_resource(struct resource *res)
>> {
>> struct platform_device *pdev;
>> struct resource *new;
>> @@ -46,8 +46,6 @@ static void __hmem_register_resource(int target_nid, struct resource *res)
>> return;
>> }
>>
>> - new->desc = target_nid;
>> -
>> if (platform_initialized)
>> return;
>>
>> @@ -64,19 +62,19 @@ static void __hmem_register_resource(int target_nid, struct resource *res)
>> platform_initialized = true;
>> }
>>
>> -void hmem_register_resource(int target_nid, struct resource *res)
>> +void hmem_register_resource(struct resource *res)
>> {
>> if (nohmem)
>> return;
>>
>> mutex_lock(&hmem_resource_lock);
>> - __hmem_register_resource(target_nid, res);
>> + __hmem_register_resource(res);
>> mutex_unlock(&hmem_resource_lock);
>> }
>>
>> static __init int hmem_register_one(struct resource *res, void *data)
>> {
>> - hmem_register_resource(phys_to_target_node(res->start), res);
>> + hmem_register_resource(res);
>>
>> return 0;
>> }
>> diff --git a/drivers/dax/hmem/hmem.c b/drivers/dax/hmem/hmem.c
>> index 5e7c53f18491..088f4060d4d5 100644
>> --- a/drivers/dax/hmem/hmem.c
>> +++ b/drivers/dax/hmem/hmem.c
>> @@ -9,6 +9,8 @@
>> static bool region_idle;
>> module_param_named(region_idle, region_idle, bool, 0644);
>>
>> +static struct platform_device *dax_hmem_pdev;
>
> I don't think you can assume there is only ever 1 hmem platform device.
>
> hmat_register_target_devices() in particular iterates multiple memory
> regions and will create more than one.
>
> What am I missing?

You may be correct that there can be more than one hmem platform device.
I was making this change based on a comment from Dan that it may not matter
which platform device these are created against.

I could be wrong in that assumption. If so we'll need to figure lout how to
determine which platform device a soft reserve resource would be created
against when they are added later in boot from a notification by the
srmem notification chain.

-Nathan

> Ira
>
>> +
>> static int dax_hmem_probe(struct platform_device *pdev)
>> {
>> unsigned long flags = IORESOURCE_DAX_KMEM;
>> @@ -59,13 +61,13 @@ static void release_hmem(void *pdev)
>> platform_device_unregister(pdev);
>> }
>>
>> -static int hmem_register_device(struct device *host, int target_nid,
>> - const struct resource *res)
>> +static int hmem_register_device(const struct resource *res)
>> {
>> + struct device *host = &dax_hmem_pdev->dev;
>> struct platform_device *pdev;
>> struct memregion_info info;
>> + int target_nid, rc;
>> long id;
>> - int rc;
>>
>> if (IS_ENABLED(CONFIG_CXL_REGION) &&
>> region_intersects(res->start, resource_size(res), IORESOURCE_MEM,
>> @@ -94,6 +96,7 @@ static int hmem_register_device(struct device *host, int target_nid,
>> return -ENOMEM;
>> }
>>
>> + target_nid = phys_to_target_node(res->start);
>> pdev->dev.numa_node = numa_map_to_online_node(target_nid);
>> info = (struct memregion_info) {
>> .target_node = target_nid,
>> @@ -125,7 +128,8 @@ static int hmem_register_device(struct device *host, int target_nid,
>>
>> static int dax_hmem_platform_probe(struct platform_device *pdev)
>> {
>> - return walk_hmem_resources(&pdev->dev, hmem_register_device);
>> + dax_hmem_pdev = pdev;
>> + return walk_hmem_resources(hmem_register_device);
>> }
>>
>> static struct platform_driver dax_hmem_platform_driver = {
>> diff --git a/include/linux/dax.h b/include/linux/dax.h
>> index 9d3e3327af4c..beaa4bcb515c 100644
>> --- a/include/linux/dax.h
>> +++ b/include/linux/dax.h
>> @@ -276,14 +276,13 @@ static inline int dax_mem2blk_err(int err)
>> }
>>
>> #ifdef CONFIG_DEV_DAX_HMEM_DEVICES
>> -void hmem_register_resource(int target_nid, struct resource *r);
>> +void hmem_register_resource(struct resource *r);
>> #else
>> -static inline void hmem_register_resource(int target_nid, struct resource *r)
>> +static inline void hmem_register_resource(struct resource *r)
>> {
>> }
>> #endif
>>
>> -typedef int (*walk_hmem_fn)(struct device *dev, int target_nid,
>> - const struct resource *res);
>> -int walk_hmem_resources(struct device *dev, walk_hmem_fn fn);
>> +typedef int (*walk_hmem_fn)(const struct resource *res);
>> +int walk_hmem_resources(walk_hmem_fn fn);
>> #endif
>> --
>> 2.43.0
>>
>>
>
>