Re: [PATCH 6/7] cxl/test: Add cxl_test accelerator driver

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

On 5/5/26 10:19 PM, Alison Schofield wrote:
> On Wed, Apr 22, 2026 at 04:02:36PM -0700, Dave Jiang wrote:
>> Add a type2 accelerator mock driver for the platform device that
>> simulates a CXL type2 device. The driver exercises the same
>> minimal API calls that a real CXL type2 driver would utilize.
>>
>> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> 
> snp
> 
>> diff --git a/tools/testing/cxl/test/accel.c b/tools/testing/cxl/test/accel.c
>> new file mode 100644
>> index 000000000000..f21fdd57034e
>> --- /dev/null
>> +++ b/tools/testing/cxl/test/accel.c
>> @@ -0,0 +1,71 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +// Copyright(c) 2026 Intel Corporation. All rights reserved.
>> +
>> +#include <linux/platform_device.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/vmalloc.h>
>> +#include <linux/module.h>
>> +#include <linux/delay.h>
>> +#include <linux/sizes.h>
>> +#include <linux/bits.h>
>> +#include <cxl/mailbox.h>
>> +#include <crypto/sha2.h>
>> +#include <cxlmem.h>
> 
> 
> Unused includes: crypto/sha2.h, linux/delay.h, linux/vmalloc.h,
> linux/bits.h. Looks copy-pasted from mem.c.

ok

> 
> 
>> +
>> +struct mock_cxl_accel {
>> +	struct cxl_dev_state cxlds;
>> +	struct cxl_memdev *cxlmd;
>> +};
>> +
>> +static int cxl_mock_accel_probe(struct platform_device *pdev)
>> +{
>> +	struct cxl_attach_region attach = {
>> +		.attach = {
>> +			.probe = cxl_memdev_attach_region,
>> +		}
>> +	};
>> +	struct mock_cxl_accel *cxl_accel;
>> +	struct cxl_dev_state *cxlds;
>> +	struct cxl_memdev *cxlmd;
>> +	int rc;
>> +
>> +	cxl_accel = devm_cxl_dev_state_create(&pdev->dev, CXL_DEVTYPE_DEVMEM,
>> +					      pdev->dev.id + 1, 0,
>> +					      struct mock_cxl_accel, cxlds,
>> +					      false);
>> +	if (!cxl_accel)
>> +		return -ENODEV;
> 
> devm_cxl_dev_state_create() NULL return means alloc failed, so 
> return should be -ENOMEM.
> 

ok

> 
>> +
>> +	cxlds = &cxl_accel->cxlds;
>> +	cxlds->media_ready = true;
>> +	rc = cxl_set_capacity(cxlds, SZ_512M);
>> +	if (rc)
>> +		return rc;
>> +
>> +	cxlmd = devm_cxl_add_memdev(cxlds, &attach.attach);
> 
> Above is storing pointer to stack allocated cxl_attach_region.
> The stack goes away when probe returns leaving cxlmd->attach
> dangling. I think we get away with it now because all our checks
> of it are NULL checks. Would it ever be derferenced? 
> Maybe devm_kzalloc attach or embed it in the the mock_cxl_accel
> so it sticks around.
> 
> 
> snip
> 
> 

I'll dynamically allocate it. The usage of 'attach' resolves when devm_cxl_add_memdev() returns. I think only place it runs into trouble is during devm cleanup. 

>> +module_platform_driver(cxl_mock_accel_driver);
>> +MODULE_LICENSE("GPL");
> 
> "GPL v2"

checkpatch suggested to use "GPL" instead of "GPL v2"

> 
>> +MODULE_DESCRIPTION("cxl_test: accelerator device mock module");
>> +MODULE_IMPORT_NS("CXL");
>> -- 
>> 2.53.0
>>