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Message-ID: <d2fd0806-6bda-41a2-a1c0-78cf55d15654@amd.com>
Date: Fri, 18 Oct 2024 11:40:36 -0500
From: Ben Cheatham <benjamin.cheatham@....com>
To: Alejandro Lucero Palau <alucerop@....com>,
<alejandro.lucero-palau@....com>
CC: <linux-cxl@...r.kernel.org>, <netdev@...r.kernel.org>,
<dan.j.williams@...el.com>, <martin.habets@...inx.com>,
<edward.cree@....com>, <davem@...emloft.net>, <kuba@...nel.org>,
<pabeni@...hat.com>, <edumazet@...gle.com>
Subject: Re: [PATCH v4 13/26] cxl: prepare memdev creation for type2
On 10/18/24 5:49 AM, Alejandro Lucero Palau wrote:
>
> On 10/17/24 22:49, Ben Cheatham wrote:
>> On 10/17/24 11:52 AM, alejandro.lucero-palau@....com wrote:
>>> From: Alejandro Lucero <alucerop@....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.
>>>
>> I agree with the sentiment that type 2 devices shouldn't have the same sysfs files,
>> but I think they should have *some* sysfs files. I would like to be able to see
>> these devices show up in something like "cxl list", which this patch would prevent.
>> I really think that it would be fine to only have the bare minimum though, such as
>> ram resource size/location, NUMA node, serial, etc.
>
>
> But this patch does not avoid all sysfs files at all, just those depending on specific type3 fields.
>
> I can see the endpoint directory related to the accelerator cxl device, and information about the region, size, start, type, ...
>
> Not sure if the ndctl cxl command should be modified for this kind of change, but I can see "cxl list -E" working.
>
Sorry, I guess that's what I get for just looking at it without testing! That should be fine
then.
>
>>> 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@....com>
>>> ---
>>> drivers/cxl/core/memdev.c | 15 +++++++++++++--
>>> drivers/cxl/core/region.c | 3 ++-
>>> drivers/cxl/mem.c | 25 +++++++++++++++++++------
>>> include/linux/cxl/cxl.h | 2 ++
>>> 4 files changed, 36 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
>>> index 56fddb0d6a85..f168cd42f8a5 100644
>>> --- a/drivers/cxl/core/memdev.c
>>> +++ b/drivers/cxl/core/memdev.c
>>> @@ -546,9 +546,17 @@ 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);
>>> @@ -659,7 +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 21ad5f242875..7e7761ff9fc4 100644
>>> --- a/drivers/cxl/core/region.c
>>> +++ b/drivers/cxl/core/region.c
>>> @@ -1941,7 +1941,8 @@ 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 7de232eaeb17..3a250ddeef35 100644
>>> --- a/drivers/cxl/mem.c
>>> +++ b/drivers/cxl/mem.c
>>> @@ -131,12 +131,18 @@ 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)
>>> @@ -222,6 +228,13 @@ 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/linux/cxl/cxl.h b/include/linux/cxl/cxl.h
>>> index b8ee42b38f68..bbbcf6574246 100644
>>> --- a/include/linux/cxl/cxl.h
>>> +++ b/include/linux/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
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