[RFC PATCH v2 3/4] scsi: ufs: add program_key() variant op

Eric Biggers
2020-03-04T06:50:17Z

On Snapdragon SoCs, the Linux kernel isn't permitted to directly access
the standard UFS crypto configuration registers. Instead, programming
and evicting keys must be done through vendor-specific SMC calls.

To support this hardware, add a ->program_key() method to
'struct ufs_hba_variant_ops'. This allows overriding the UFS standard
key programming / eviction procedure.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
drivers/scsi/ufs/ufshcd-crypto.c | 34 +++++++++++++++++++++-----------
drivers/scsi/ufs/ufshcd.h | 3 +++
2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-crypto.c b/drivers/scsi/ufs/ufshcd-crypto.c
index cd7ca50a1dd9..7c50d1d4f58c 100644
--- a/drivers/scsi/ufs/ufshcd-crypto.c
+++ b/drivers/scsi/ufs/ufshcd-crypto.c
@@ -131,14 +131,20 @@ static int ufshcd_crypto_cfg_entry_write_key(union ufs_crypto_cfg_entry *cfg,
return -EINVAL;
}

-static void ufshcd_program_key(struct ufs_hba *hba,
- const union ufs_crypto_cfg_entry *cfg,
- int slot)
+static int ufshcd_program_key(struct ufs_hba *hba,
+ const union ufs_crypto_cfg_entry *cfg, int slot)
{
int i;
u32 slot_offset = hba->crypto_cfg_register + slot * sizeof(*cfg);
+ int err = 0;

ufshcd_hold(hba, false);
+
+ if (hba->vops && hba->vops->program_key) {
+ err = hba->vops->program_key(hba, cfg, slot);
+ goto out;
+ }
+
/* Ensure that CFGE is cleared before programming the key */
ufshcd_writel(hba, 0, slot_offset + 16 * sizeof(cfg->reg_val[0]));
for (i = 0; i < 16; i++) {
@@ -151,23 +157,28 @@ static void ufshcd_program_key(struct ufs_hba *hba,
/* Dword 16 must be written last */
ufshcd_writel(hba, le32_to_cpu(cfg->reg_val[16]),
slot_offset + 16 * sizeof(cfg->reg_val[0]));
+out:
ufshcd_release(hba);
+ return err;
}

-static void ufshcd_clear_keyslot(struct ufs_hba *hba, int slot)
+static int ufshcd_clear_keyslot(struct ufs_hba *hba, int slot)
{
union ufs_crypto_cfg_entry cfg = { 0 };

- ufshcd_program_key(hba, &cfg, slot);
+ return ufshcd_program_key(hba, &cfg, slot);
}

/* Clear all keyslots at driver init time */
static void ufshcd_clear_all_keyslots(struct ufs_hba *hba)
{
int slot;
+ int err;

- for (slot = 0; slot < ufshcd_num_keyslots(hba); slot++)
- ufshcd_clear_keyslot(hba, slot);
+ for (slot = 0; slot < ufshcd_num_keyslots(hba); slot++) {
+ err = ufshcd_clear_keyslot(hba, slot);
+ WARN_ON_ONCE(err);
+ }
}

static int ufshcd_crypto_keyslot_program(struct keyslot_manager *ksm,
@@ -203,10 +214,11 @@ static int ufshcd_crypto_keyslot_program(struct keyslot_manager *ksm,
if (err)
return err;

- ufshcd_program_key(hba, &cfg, slot);
+ err = ufshcd_program_key(hba, &cfg, slot);

memzero_explicit(&cfg, sizeof(cfg));
- return 0;
+
+ return err;
}

static int ufshcd_crypto_keyslot_evict(struct keyslot_manager *ksm,
@@ -223,9 +235,7 @@ static int ufshcd_crypto_keyslot_evict(struct keyslot_manager *ksm,
* Clear the crypto cfg on the device. Clearing CFGE
* might not be sufficient, so just clear the entire cfg.
*/
- ufshcd_clear_keyslot(hba, slot);
-
- return 0;
+ return ufshcd_clear_keyslot(hba, slot);
}

void ufshcd_crypto_enable(struct ufs_hba *hba)
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index c8f948aa5e3d..c2656575e24b 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -306,6 +306,7 @@ struct ufs_pwr_mode_info {
* @dbg_register_dump: used to dump controller debug information
* @phy_initialization: used to initialize phys
* @device_reset: called to issue a reset pulse on the UFS device
+ * @program_key: program or evict an inline encryption key
*/
struct ufs_hba_variant_ops {
const char *name;
@@ -335,6 +336,8 @@ struct ufs_hba_variant_ops {
void (*dbg_register_dump)(struct ufs_hba *hba);
int (*phy_initialization)(struct ufs_hba *);
void (*device_reset)(struct ufs_hba *hba);
+ int (*program_key)(struct ufs_hba *hba,
+ const union ufs_crypto_cfg_entry *cfg, int slot);
};

/* clock gating state */
--
2.25.1