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

Ira Weiny
2025-01-16T22:29:23Z

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?
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
>
>