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

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

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?
> 

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
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.

> Best regards,
> Krzysztof