Re: [PATCH RFC 11/15] cxl/pmem: Add "Unlock" security command support

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Fri, 15 Jul 2022 14:09:36 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Create callback function to support the nvdimm_security_ops() ->unlock()
> callback. Translate the operation to send "Unlock" security command for CXL
> mem device.
> 
> When the mem device is unlocked, arch_invalidate_nvdimm_cache() is called
> in order to invalidate all CPU caches before attempting to access the mem
> device.
> 
> See CXL 2.0 spec section 8.2.9.5.6.4 for reference.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Hi Dave,

One trivial thing inline.

Thanks,

Jonathan

> ---
>  drivers/cxl/cxlmem.h   |    1 +
>  drivers/cxl/security.c |   21 +++++++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> index ced85be291f3..ae8ccd484491 100644
> --- a/drivers/cxl/cxlmem.h
> +++ b/drivers/cxl/cxlmem.h
> @@ -253,6 +253,7 @@ enum cxl_opcode {
>  	CXL_MBOX_OP_GET_SECURITY_STATE	= 0x4500,
>  	CXL_MBOX_OP_SET_PASSPHRASE	= 0x4501,
>  	CXL_MBOX_OP_DISABLE_PASSPHRASE	= 0x4502,
> +	CXL_MBOX_OP_UNLOCK		= 0x4503,
>  	CXL_MBOX_OP_FREEZE_SECURITY	= 0x4504,
>  	CXL_MBOX_OP_MAX			= 0x10000
>  };
> diff --git a/drivers/cxl/security.c b/drivers/cxl/security.c
> index 6399266a5908..d15520f280f0 100644
> --- a/drivers/cxl/security.c
> +++ b/drivers/cxl/security.c
> @@ -114,11 +114,32 @@ static int cxl_pmem_security_freeze(struct nvdimm *nvdimm)
>  	return cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_FREEZE_SECURITY, NULL, 0, NULL, 0);
>  }
>  
> +static int cxl_pmem_security_unlock(struct nvdimm *nvdimm,
> +				    const struct nvdimm_key_data *key_data)
> +{
> +	struct cxl_nvdimm *cxl_nvd = nvdimm_provider_data(nvdimm);
> +	struct cxl_memdev *cxlmd = cxl_nvd->cxlmd;
> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +	u8 pass[NVDIMM_PASSPHRASE_LEN];
> +	int rc;
> +
> +	memcpy(pass, key_data->data, NVDIMM_PASSPHRASE_LEN);

Why do we need a local copy?  I'd have thought we could just
pass keydata->data in as the payload for cxl_mbox_send_cmd()
There might be some value in making it easier to check by
having a structure defined for this payload (obviously trivial)
but given we are using an array of length defined by a non CXL
define, I'm not sure there is any point in the copy.

> +	rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_UNLOCK,
> +			       pass, NVDIMM_PASSPHRASE_LEN, NULL, 0);
> +	if (rc < 0)
> +		return rc;
> +
> +	/* DIMM unlocked, invalidate all CPU caches before we read it */
> +	arch_invalidate_nvdimm_cache();
> +	return 0;
> +}
> +
>  static const struct nvdimm_security_ops __cxl_security_ops = {
>  	.get_flags = cxl_pmem_get_security_flags,
>  	.change_key = cxl_pmem_security_change_key,
>  	.disable = cxl_pmem_security_disable,
>  	.freeze = cxl_pmem_security_freeze,
> +	.unlock = cxl_pmem_security_unlock,
>  };
>  
>  const struct nvdimm_security_ops *cxl_security_ops = &__cxl_security_ops;
> 
>