[PATCH v2 13/14] arm64: rsi: Interfaces to query attestation token

[Steven Price]

From: Sami Mujawar <sami.mujawar at arm.com>

Add interfaces to query the attestation token using
the RSI calls.

Signed-off-by: Sami Mujawar <sami.mujawar at arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
Signed-off-by: Steven Price <steven.price at arm.com>
---
 arch/arm64/include/asm/rsi_cmds.h | 74 +++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

diff --git a/arch/arm64/include/asm/rsi_cmds.h b/arch/arm64/include/asm/rsi_cmds.h
index b4cbeafa2f41..c1850aefe54e 100644
--- a/arch/arm64/include/asm/rsi_cmds.h
+++ b/arch/arm64/include/asm/rsi_cmds.h
@@ -10,6 +10,9 @@
 
 #include <asm/rsi_smc.h>
 
+#define GRANULE_SHIFT		12
+#define GRANULE_SIZE		(_AC(1, UL) << GRANULE_SHIFT)
+
 enum ripas {
 	RSI_RIPAS_EMPTY,
 	RSI_RIPAS_RAM,
@@ -66,4 +69,75 @@ static inline unsigned long rsi_set_addr_range_state(phys_addr_t start,
 	return res.a0;
 }
 
+/**
+ * rsi_attestation_token_init - Initialise the operation to retrieve an
+ * attestation token.
+ *
+ * @challenge:	The challenge data to be used in the attestation token
+ *		generation.
+ * @size:	Size of the challenge data in bytes.
+ *
+ * Initialises the attestation token generation and returns an upper bound
+ * on the attestation token size that can be used to allocate an adequate
+ * buffer. The caller is expected to subsequently call
+ * rsi_attestation_token_continue() to retrieve the attestation token data on
+ * the same CPU.
+ *
+ * Returns:
+ *  On success, returns the upper limit of the attestation report size.
+ *  Otherwise, -EINVAL
+ */
+static inline unsigned long
+rsi_attestation_token_init(const u8 *challenge, unsigned long size)
+{
+	struct arm_smccc_1_2_regs regs = { 0 };
+
+	/* The challenge must be at least 32bytes and at most 64bytes */
+	if (!challenge || size < 32 || size > 64)
+		return -EINVAL;
+
+	regs.a0 = SMC_RSI_ATTESTATION_TOKEN_INIT;
+	memcpy(&regs.a1, challenge, size);
+	arm_smccc_1_2_smc(&regs, &regs);
+
+	if (regs.a0 == RSI_SUCCESS)
+		return regs.a1;
+
+	return -EINVAL;
+}
+
+/**
+ * rsi_attestation_token_continue - Continue the operation to retrieve an
+ * attestation token.
+ *
+ * @granule: {I}PA of the Granule to which the token will be written.
+ * @offset:  Offset within Granule to start of buffer in bytes.
+ * @size:    The size of the buffer.
+ * @len:     The number of bytes written to the buffer.
+ *
+ * Retrieves up to a GRANULE_SIZE worth of token data per call. The caller is
+ * expected to call rsi_attestation_token_init() before calling this function
+ * to retrieve the attestation token.
+ *
+ * Return:
+ * * %RSI_SUCCESS     - Attestation token retrieved successfully.
+ * * %RSI_INCOMPLETE  - Token generation is not complete.
+ * * %RSI_ERROR_INPUT - A parameter was not valid.
+ * * %RSI_ERROR_STATE - Attestation not in progress.
+ */
+static inline int rsi_attestation_token_continue(phys_addr_t granule,
+						 unsigned long offset,
+						 unsigned long size,
+						 unsigned long *len)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_invoke(SMC_RSI_ATTESTATION_TOKEN_CONTINUE,
+			     granule, offset, size, 0, &res);
+
+	if (len)
+		*len = res.a1;
+	return res.a0;
+}
+
 #endif
-- 
2.34.1