Re: [PATCH v17 08/22] cxl: Prepare memdev creation for type2

[<dan.j.williams@intel.com>]

alejandro.lucero-palau@ wrote:
> From: Alejandro Lucero <alucerop@amd.com>
> 
> Current cxl core is relying on a CXL_DEVTYPE_CLASSMEM type device when
> creating a memdev leading to problems when obtaining cxl_memdev_state
> references from a CXL_DEVTYPE_DEVMEM type.
> 
> Modify check for obtaining cxl_memdev_state adding CXL_DEVTYPE_DEVMEM
> support.
> 
> Make devm_cxl_add_memdev accessible from a accel driver.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> Reviewed-by: Ben Cheatham <benjamin.cheatham@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/cxl/core/memdev.c | 15 +++++++++++++--
>  drivers/cxl/cxlmem.h      |  2 --
>  drivers/cxl/mem.c         | 25 +++++++++++++++++++------
>  include/cxl/cxl.h         |  2 ++
>  4 files changed, 34 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index c73582d24dd7..f43d2aa2928e 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -7,6 +7,7 @@
>  #include <linux/slab.h>
>  #include <linux/idr.h>
>  #include <linux/pci.h>
> +#include <cxl/cxl.h>
>  #include <cxlmem.h>
>  #include "trace.h"
>  #include "core.h"
> @@ -562,9 +563,16 @@ static const struct device_type cxl_memdev_type = {
>  	.groups = cxl_memdev_attribute_groups,
>  };
>  
> +static const struct device_type cxl_accel_memdev_type = {
> +	.name = "cxl_accel_memdev",
> +	.release = cxl_memdev_release,
> +	.devnode = cxl_memdev_devnode,
> +};
> +
>  bool is_cxl_memdev(const struct device *dev)
>  {
> -	return dev->type == &cxl_memdev_type;
> +	return (dev->type == &cxl_memdev_type ||
> +		dev->type == &cxl_accel_memdev_type);
>  }
>  EXPORT_SYMBOL_NS_GPL(is_cxl_memdev, "CXL");
>  
> @@ -689,7 +697,10 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_dev_state *cxlds,
>  	dev->parent = cxlds->dev;
>  	dev->bus = &cxl_bus_type;
>  	dev->devt = MKDEV(cxl_mem_major, cxlmd->id);
> -	dev->type = &cxl_memdev_type;
> +	if (cxlds->type == CXL_DEVTYPE_DEVMEM)
> +		dev->type = &cxl_accel_memdev_type;
> +	else
> +		dev->type = &cxl_memdev_type;
>  	device_set_pm_not_required(dev);
>  	INIT_WORK(&cxlmd->detach_work, detach_memdev);
>  
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index 9cc4337cacfb..7be51f70902a 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -88,8 +88,6 @@ static inline bool is_cxl_endpoint(struct cxl_port *port)
>  	return is_cxl_memdev(port->uport_dev);
>  }
>  
> -struct cxl_memdev *devm_cxl_add_memdev(struct device *host,
> -				       struct cxl_dev_state *cxlds);
>  int devm_cxl_sanitize_setup_notifier(struct device *host,
>  				     struct cxl_memdev *cxlmd);
>  struct cxl_memdev_state;
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 9675243bd05b..7f39790d9d98 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -130,12 +130,18 @@ static int cxl_mem_probe(struct device *dev)
>  	dentry = cxl_debugfs_create_dir(dev_name(dev));
>  	debugfs_create_devm_seqfile(dev, "dpamem", dentry, cxl_mem_dpa_show);
>  
> -	if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
> -		debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
> -				    &cxl_poison_inject_fops);
> -	if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
> -		debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
> -				    &cxl_poison_clear_fops);
> +	/*
> +	 * Avoid poison debugfs files for Type2 devices as they rely on
> +	 * cxl_memdev_state.
> +	 */

I know this already has my Reviewed-by, but this comment is going to
annoying long term. The CXL specification has already dropped "Type2" as
a name and Linux has already called this DEVMEM, and the comment belongs
on a helper.

Just call a new cxl_memdev_poison_enable() helper unconditionally, put
the mds NULL check inside of it and comment on that helper:

/* For CLASSMEM memory expanders enable poison injection */
cxl_memdev_poison_enable()

> +	if (mds) {
> +		if (test_bit(CXL_POISON_ENABLED_INJECT, mds->poison.enabled_cmds))
> +			debugfs_create_file("inject_poison", 0200, dentry, cxlmd,
> +					    &cxl_poison_inject_fops);
> +		if (test_bit(CXL_POISON_ENABLED_CLEAR, mds->poison.enabled_cmds))
> +			debugfs_create_file("clear_poison", 0200, dentry, cxlmd,
> +					    &cxl_poison_clear_fops);
> +	}
>  
>  	rc = devm_add_action_or_reset(dev, remove_debugfs, dentry);
>  	if (rc)
> @@ -219,6 +225,13 @@ static umode_t cxl_mem_visible(struct kobject *kobj, struct attribute *a, int n)
>  	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
>  	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
>  
> +	/*
> +	 * Avoid poison sysfs files for Type2 devices as they rely on
> +	 * cxl_memdev_state.
> +	 */
> +	if (!mds)
> +		return 0;
> +
>  	if (a == &dev_attr_trigger_poison_list.attr)
>  		if (!test_bit(CXL_POISON_ENABLED_LIST,
>  			      mds->poison.enabled_cmds))

Same here, do not sprinle an "if (!mds)" check add a:

cxl_poison_attr_visible() helper and call it unconditionally in the "if
(a == &dev_attr_trigger_poison_list.attr)" case.