Re: [PATCH v1 02/11] soc: qcom: add crypto_virt backend for virtio-blk inline crypto

[Linlin Zhang <linlin.zhang@oss.qualcomm.com>]

On 9/1/2026 9:58 PM, Krzysztof Kozlowski wrote:
> On 01/09/2026 11:39, Linlin Zhang wrote:
>>
>>
>> On 8/31/2026 2:56 PM, Krzysztof Kozlowski wrote:
>>> On 27/08/2026 18:07, Linlin Zhang wrote:
>>>> From: linlzhan <linlin.zhang@oss.qualcomm.com>
>>>>
>>>> In a Qualcomm GVM environment the ICE hardware is controlled by the
>>>
>>> What is GVM?
> 
> There is no such TLA (git grep).
> 
> Maybe you meant guest in a virtual machine? Don't use some qcom-specific
> TLA.
> 

ACK
> 
>>>
>>
>> GVM means Guest Virtual Machine. This is designed for the virtualization
>> platform.
>>
>>>> host, GVM has no direct access to it. So, key operation in GVM is
>>>> done through SCM calls rather than direct register access. In this
>>>> way the access to ICE registers are offloaded to Trust Zone.
>>>>
>>>> Add QCOM_CRYPTO_VIRT, which implements struct virtblk_crypto_variant_ops
>>>> for the virtio_blk_crypto_ext dispatch layer. It maps keyslot
>>>> program/evict to qcom_scm_ice_set_key() and
>>>> qcom_scm_ice_invalidate_key(), and software-secret derivation to
>>>> qcom_scm_derive_sw_secret().
>>>>
>>>> Signed-off-by: linlzhan <linlin.zhang@oss.qualcomm.com>
>>>> ---
>>>>  drivers/soc/qcom/Kconfig       | 12 +++++
>>>>  drivers/soc/qcom/Makefile      |  1 +
>>>>  drivers/soc/qcom/crypto_virt.c | 89 ++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 102 insertions(+)
>>>>  create mode 100644 drivers/soc/qcom/crypto_virt.c
>>>>
>>>> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
>>>> index 2b524154d9fb..6c632d114d45 100644
>>>> --- a/drivers/soc/qcom/Kconfig
>>>> +++ b/drivers/soc/qcom/Kconfig
>>>> @@ -298,6 +298,18 @@ config QCOM_INLINE_CRYPTO_ENGINE
>>>>  	tristate
>>>>  	select QCOM_SCM
>>>>  
>>>> +config QCOM_CRYPTO_VIRT
>>>> +	tristate "Qualcomm Technologies, Inc. Crypto Virt driver"
>>>> +	depends on VIRTBLK_CRYPTO_VIRTUALIZATION
>>>> +	depends on QCOM_SCM
>>>> +	default VIRTBLK_CRYPTO_VIRTUALIZATION if ARCH_QCOM
>>>> +	help
>>>> +	  GVM-side hardware-wrapped-key SCM operations exposed to
>>>> +	  virtio_blk's inline crypto layer: per-slot key programming and
>>>> +	  eviction, and key derive/generate/prepare/import.
>>>> +	  Say Y here to compile the driver as a part of kernel or M to compile
>>>> +	  as a module.
>>>> +
>>>>  config QCOM_KRYO_L2_ACCESSORS
>>>>  	bool
>>>>  	depends on ARM64
>>>> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
>>>> index 798643be3590..6d4b7546d1fb 100644
>>>> --- a/drivers/soc/qcom/Makefile
>>>> +++ b/drivers/soc/qcom/Makefile
>>>> @@ -39,5 +39,6 @@ obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
>>>>  obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o
>>>>  qcom_ice-objs			+= ice.o
>>>>  obj-$(CONFIG_QCOM_INLINE_CRYPTO_ENGINE)	+= qcom_ice.o
>>>> +obj-$(CONFIG_QCOM_CRYPTO_VIRT)	+= crypto_virt.o
>>>>  obj-$(CONFIG_QCOM_PBS) +=	qcom-pbs.o
>>>>  obj-$(CONFIG_QCOM_UBWC_CONFIG) += ubwc_config.o
>>>> diff --git a/drivers/soc/qcom/crypto_virt.c b/drivers/soc/qcom/crypto_virt.c
>>>> new file mode 100644
>>>> index 000000000000..4ee2a36af6c1
>>>> --- /dev/null
>>>> +++ b/drivers/soc/qcom/crypto_virt.c
>>>> @@ -0,0 +1,89 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +
>>>> +#include <linux/module.h>
>>>> +#include <linux/types.h>
>>>> +#include <linux/blk-crypto.h>
>>>> +#include <linux/virtio_blk_crypto_ext.h>
>>>> +#include <linux/firmware/qcom/qcom_scm.h>
>>>> +
>>>> +static int crypto_virt_program_key(const struct blk_crypto_key *key,
>>>> +				   unsigned int slot)
>>>> +{
>>>> +	u32 dus_512_units;
>>>> +	int ret;
>>>> +
>>>> +	if (!key || !key->size) {
>>>> +		pr_err("%s: invalid key\n", __func__);
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	/* Only AES-256-XTS has been tested so far. */
>>>> +	if (key->crypto_cfg.crypto_mode !=
>>>> +	    BLK_ENCRYPTION_MODE_AES_256_XTS) {
>>>> +		pr_err_ratelimited("Unsupported crypto mode: %d\n",
>>>> +				    key->crypto_cfg.crypto_mode);
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	/* qcom_scm_ice_set_key()'s data_unit_size is expressed in 512-byte units */
>>>> +	dus_512_units = key->crypto_cfg.data_unit_size / 512;
>>>> +
>>>> +	ret = qcom_scm_ice_set_key(slot, key->bytes, key->size,
>>>> +		QCOM_SCM_ICE_CIPHER_AES_256_XTS, dus_512_units);
>>>> +	if (ret)
>>>> +		pr_err("%s: slot=%u ret=%d\n", __func__, slot, ret);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int crypto_virt_invalidate_key(unsigned int slot)
>>>> +{
>>>> +	int ret;
>>>> +
>>>> +	ret = qcom_scm_ice_invalidate_key(slot);
>>>> +	if (ret)
>>>> +		pr_err("%s: slot=%u ret=%d\n", __func__, slot, ret);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int crypto_virt_derive_sw_secret_key(const u8 *eph_key, size_t eph_key_size,
>>>> +					    u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE])
>>>> +{
>>>> +	int ret;
>>>> +
>>>> +	ret = qcom_scm_derive_sw_secret(eph_key, eph_key_size,
>>>> +					sw_secret, BLK_CRYPTO_SW_SECRET_SIZE);
>>>> +	if (ret == -EIO || ret == -EINVAL)
>>>> +		ret = -EBADMSG; /* probably invalid key */
>>>> +
>>>> +	if (ret)
>>>> +		pr_err("%s: ret=%d\n", __func__, ret);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static struct virtblk_crypto_variant_ops virtblk_crypto_qcom_vops = {
>>>
>>> Why is a crypto-handling code in drivers/soc/?
>>>
>>
>> This driver is a Qualcomm vendor-specific driver, plays the similar role in the
> 
> Not really, there is nothing vendor specific here. Look at this code.
> 

crypto_virt_program_key calls the interface from qcom_scm driver. Similar to
crypto_virt_invalidate_key and crypto_virt_derive_sw_secret_key.

>> guest, like the ice driver in the host. so I place it in drivers/soc/.
>>
>>>> +	.owner = THIS_MODULE,
>>>> +	.program_key = crypto_virt_program_key,
>>>> +	.evict_key = crypto_virt_invalidate_key,
>>>> +	.derive_sw_secret_key = crypto_virt_derive_sw_secret_key,
>>>> +};
>>>> +
>>>> +static int __init crypto_virt_init(void)
>>>> +{
>>>> +	virtblk_set_crypto_ops(&virtblk_crypto_qcom_vops);
>>>> +	return 0;
>>>> +}
>>>> +module_init(crypto_virt_init);
>>>> +
>>>> +#if IS_MODULE(CONFIG_QCOM_CRYPTO_VIRT)
>>>> +static void __exit crypto_virt_exit(void)
>>>> +{
>>>> +	virtblk_set_crypto_ops(NULL);
>>>> +}
>>>> +module_exit(crypto_virt_exit);
>>>> +#endif
>>>
>>> How do you instantiate this driver exactly?
>>>
>>
>> This driver is not instantiated per device. It acts as a provider of
>> Qualcomm vendor-specific inline crypto operations, which is based on
>> qcom_scm driver, and registers a global virtblk_crypto_ops instance
>> during module initialization. So that, each blk_crypto_ll_ops from
>> virtio block driver in common kernel can be sent via qcom_smc driver.
> 
> 
> If it is not instantiated, then it is dead code. Drop all this. Or read
> my message again very carefully instead of replying with whatever copy
> of commit msg. I did not ask what is this driver about. I did not ask
> what it is providing. I asked how do you instantiate it or clarifying -
> how do you load and run this code in final system.
> 

I agree this does not fit well with the usual Linux driver model, since
there is no device instance, probe path, or explicit lifetime
relationship between virtio-blk and the crypto_virt backend.

Given that, I think the current global registration approach is difficult
to justify upstream and I will revisit the design.

> This is just dead/unused code, straight from downstream.
> 
> NAK.
> 
> 
> Best regards,
> Krzysztof