Re: [PATCH v5 13/27] cxl: prepare memdev creation for type2

[Dave Jiang <dave.jiang@intel.com>]

On 11/18/24 9:44 AM, alejandro.lucero-palau@amd.com 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. This last device type is
> managed by a specific vendor driver and does not need same sysfs files
> since not userspace intervention is expected.
> 
> Create a new cxl_mem device type with no attributes for Type2.
> 
> Avoid debugfs files relying on existence of clx_memdev_state.
> 
> Make devm_cxl_add_memdev accesible from a accel driver.
> 
> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> ---
>  drivers/cxl/core/cdat.c   |  3 +++
>  drivers/cxl/core/memdev.c | 15 +++++++++++++--
>  drivers/cxl/core/region.c |  3 ++-
>  drivers/cxl/mem.c         | 25 +++++++++++++++++++------
>  include/cxl/cxl.h         |  2 ++
>  5 files changed, 39 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
> index e9cd7939c407..192cff18ea25 100644
> --- a/drivers/cxl/core/cdat.c
> +++ b/drivers/cxl/core/cdat.c
> @@ -577,6 +577,9 @@ static struct cxl_dpa_perf *cxled_get_dpa_perf(struct cxl_endpoint_decoder *cxle
>  	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
>  	struct cxl_dpa_perf *perf;
>  
> +	if (!mds)
> +		return ERR_PTR(-EINVAL);
> +
>  	switch (mode) {
>  	case CXL_DECODER_RAM:
>  		perf = &mds->ram_perf;
> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
> index d746c8a1021c..df31eea0c06b 100644
> --- a/drivers/cxl/core/memdev.c
> +++ b/drivers/cxl/core/memdev.c
> @@ -547,9 +547,17 @@ static const struct device_type cxl_memdev_type = {
>  	.groups = cxl_memdev_attribute_groups,
>  };
>  
> +static const struct device_type cxl_accel_memdev_type = {
> +	.name = "cxl_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);

Does type2 device also exports a CDAT?

I'm also wondering if we should have distinctive helpers:
is_cxl_type3_memdev()
is_cxl_type2_memdev()

and is_cxl_memdev() is just calling those two helpers above. 

And if no CDAT is exported, we should change the is_cxl_memdev() to is_cxl_type3_memdev() in read_cdat_data(). 

DJ

>  
> @@ -660,7 +668,10 @@ 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/core/region.c b/drivers/cxl/core/region.c
> index dff618c708dc..622e3bb2e04b 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1948,7 +1948,8 @@ static int cxl_region_attach(struct cxl_region *cxlr,
>  		return -EINVAL;
>  	}
>  
> -	cxl_region_perf_data_calculate(cxlr, cxled);
> +	if (cxlr->type == CXL_DECODER_HOSTONLYMEM)
> +		cxl_region_perf_data_calculate(cxlr, cxled);
>  
>  	if (test_bit(CXL_REGION_F_AUTO, &cxlr->flags)) {
>  		int i;
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index a9fd5cd5a0d2..cb771bf196cd 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.
> +	 */
> +	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))
> diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
> index 6033ce84b3d3..5608ed0f5f15 100644
> --- a/include/cxl/cxl.h
> +++ b/include/cxl/cxl.h
> @@ -57,4 +57,6 @@ int cxl_pci_accel_setup_regs(struct pci_dev *pdev, struct cxl_dev_state *cxlds);
>  int cxl_request_resource(struct cxl_dev_state *cxlds, enum cxl_resource type);
>  int cxl_release_resource(struct cxl_dev_state *cxlds, enum cxl_resource type);
>  void cxl_set_media_ready(struct cxl_dev_state *cxlds);
> +struct cxl_memdev *devm_cxl_add_memdev(struct device *host,
> +				       struct cxl_dev_state *cxlds);
>  #endif