[kvm-unit-tests PATCH 28/33] arm: realm: Add helpers to decode RSI return codes

Suzuki K Poulose
2024-04-12T10:39:01Z

RMM encodes error code and index in the result of an operation.
Add helpers to decode this information for use with the attestation
tests.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
lib/arm64/asm/rsi.h | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)

diff --git a/lib/arm64/asm/rsi.h b/lib/arm64/asm/rsi.h
index 2566c000..c7d65333 100644
--- a/lib/arm64/asm/rsi.h
+++ b/lib/arm64/asm/rsi.h
@@ -16,6 +16,39 @@

extern bool rsi_present;

+/*
+ * Logical representation of return code returned by RMM commands.
+ * Each failure mode of a given command should return a unique return code, so
+ * that the caller can use it to unambiguously identify the failure mode. To
+ * avoid having a very large list of enumerated values, the return code is
+ * composed of a status which identifies the category of the error (for example,
+ * an address was misaligned), and an index which disambiguates between multiple
+ * similar failure modes (for example, a command may take multiple addresses as
+ * its input; the index identifies _which_ of them was misaligned.)
+ */
+typedef unsigned int status_t;
+typedef struct {
+ status_t status;
+ unsigned int index;
+} return_code_t;
+
+/*
+ * Convenience function for creating a return_code_t.
+ */
+static inline return_code_t make_return_code(unsigned int status,
+ unsigned int index)
+{
+ return (return_code_t) {status, index};
+}
+
+/*
+ * Unpacks a return code.
+ */
+static inline return_code_t unpack_return_code(unsigned long error_code)
+{
+ return make_return_code(error_code & 0xff, error_code >> 8);
+}
+
void arm_rsi_init(void);

int rsi_invoke(unsigned int function_id, unsigned long arg0,