Re: [PATCH v8 13/27] cxl: prepare memdev creation for type2

[Alejandro Lucero Palau <alucerop@amd.com>]

On 12/24/24 17:32, Jonathan Cameron wrote:
> On Mon, 16 Dec 2024 16:10:28 +0000
> 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 cxl_memdev_state.
>>
>> Make devm_cxl_add_memdev accesible from a accel driver.
> You've added it to a header, but not removed it from a different
> one. That is generally a bad plan.


That's true. I'll remove it from cxlmem.h


>
> I'm curious on the poison part.  Does your device support the command?
> If so we probably want to think about what is needed to enable that long term.
>
> Jonathan
>

Our device has not a mailbox ...


But you are right. The problem is the structs which, I think, requires a 
refactoring.


This patch is the fastpath for initial type2 support. I hope with new 
clients, and likely with the qemu patch from Zhi for type2, the 
refactoring can be properly done with more exposure to type2 cases.



>> Signed-off-by: Alejandro Lucero <alucerop@amd.com>
>> ---
>>   drivers/cxl/core/cdat.c   |  3 +++
>>   drivers/cxl/core/memdev.c | 14 ++++++++++++--
>>   drivers/cxl/core/region.c |  3 ++-
>>   drivers/cxl/mem.c         | 25 +++++++++++++++++++------
>>   include/cxl/cxl.h         |  2 ++
>>   5 files changed, 38 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
>> index 8153f8d83a16..c57bc83e79ee 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 82c354b1375e..4d24305624e0 100644
>> --- a/drivers/cxl/core/memdev.c
>> +++ b/drivers/cxl/core/memdev.c
>> @@ -547,9 +547,16 @@ 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");
>>   
>> @@ -660,7 +667,10 @@ 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 d77899650798..967132b49832 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 2f03a4d5606e..93106a43990b 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 473128fdfb22..26d7735b5f31 100644
>> --- a/include/cxl/cxl.h
>> +++ b/include/cxl/cxl.h
>> @@ -45,4 +45,6 @@ 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