xen/arm: ffa: add defines for sharing memory

According to DEN0077A version 1.1 REL0
- Section 10.9.2 Memory region handle, page 167
- Table 10.18 at page 175
- Table 10.15 at page 168
- Section 10.11.4 Flags usage, page 184-187
add defines needed for sharing using the function FFA_MEM_SHARE and
friends.

Also add limits for how many shared buffers that a guest can have at
once and how large a shared buffer can be at most.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Henry Wang <Henry.Wang@arm.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>

xen/arch/arm/tee/ffa.c

@@ -5,6 +5,14 @@
  * Arm Firmware Framework for ARMv8-A (FF-A) mediator
  *
  * Copyright (C) 2023  Linaro Limited
+ *
+ * References:
+ * FF-A-1.0-REL: FF-A specification version 1.0 available at
+ *               https://developer.arm.com/documentation/den0077/a
+ * FF-A-1.1-REL0: FF-A specification version 1.1 available at
+ *                https://developer.arm.com/documentation/den0077/e
+ * TEEC-1.0C: TEE Client API Specification version 1.0c available at
+ *            https://globalplatform.org/specs-library/tee-client-api-specification/
  */
 
 #include <xen/bitops.h>
@@ -80,6 +88,56 @@
  */
 #define FFA_MAX_RXTX_PAGE_COUNT         1
 
+/*
+ * Limit for shared buffer size. Please note that this define limits
+ * number of pages.
+ *
+ * FF-A doesn't have any direct requirements on GlobalPlatform or vice
+ * versa, but an implementation can very well use FF-A in order to provide
+ * a GlobalPlatform interface on top.
+ *
+ * Global Platform specification for TEE requires that any TEE
+ * implementation should allow to share buffers with size of at least
+ * 512KB, defined in TEEC-1.0C page 24, Table 4-1,
+ * TEEC_CONFIG_SHAREDMEM_MAX_SIZE.
+ * Due to overhead which can be hard to predict exactly, double this number
+ * to give a safe margin.
+ */
+#define FFA_MAX_SHM_PAGE_COUNT          (2 * SZ_512K / FFA_PAGE_SIZE)
+
+/*
+ * Limits the number of shared buffers that guest can have at once. This
+ * is to prevent case, when guests trick XEN into exhausting its own
+ * memory by allocating many small buffers. This value has been chosen
+ * arbitrarily.
+ */
+#define FFA_MAX_SHM_COUNT               32
+
+/* FF-A-1.1-REL0 section 10.9.2 Memory region handle, page 167 */
+#define FFA_HANDLE_HYP_FLAG             BIT(63, ULL)
+#define FFA_HANDLE_INVALID              0xffffffffffffffffULL
+
+/*
+ * Memory attributes: Normal memory, Write-Back cacheable, Inner shareable
+ * Defined in FF-A-1.1-REL0 Table 10.18 at page 175.
+ */
+#define FFA_NORMAL_MEM_REG_ATTR         0x2fU
+/*
+ * Memory access permissions: Read-write
+ * Defined in FF-A-1.1-REL0 Table 10.15 at page 168.
+ */
+#define FFA_MEM_ACC_RW                  0x2U
+
+/* FF-A-1.1-REL0 section 10.11.4 Flags usage, page 184-187 */
+/* Clear memory before mapping in receiver */
+#define FFA_MEMORY_REGION_FLAG_CLEAR            BIT(0, U)
+/* Relayer may time slice this operation */
+#define FFA_MEMORY_REGION_FLAG_TIME_SLICE       BIT(1, U)
+/* Clear memory after receiver relinquishes it */
+#define FFA_MEMORY_REGION_FLAG_CLEAR_RELINQUISH BIT(2, U)
+/* Share memory transaction */
+#define FFA_MEMORY_REGION_TRANSACTION_TYPE_SHARE (1U << 3)
+
 /*
  * Flags and field values used for the MSG_SEND_DIRECT_REQ/RESP:
  * BIT(31): Framework or partition message