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

[Alison Schofield <alison.schofield@intel.com>]

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.


> +
> +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.


> +
> +	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


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

"GPL v2"

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