xen/arm: ffa: add v1.2 SEND2 header layout

Teach the SEND2 path about the distinct FF-A v1.1 and v1.2 RX/TX header
layouts so we can propagate the 128-bit UUIDs introduced in v1.2.

VM-to-VM SEND2 calls now build the larger v1.2 header, zeroing the UUID
fields for v1.1 senders, and the dispatcher validates messages using
the v1.1 header layout to keep legacy guests working.

While there, make the code more robust by checking that the send is not
trying to send a message to himself.

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

xen/arch/arm/tee/ffa_msg.c

@@ -13,7 +13,7 @@
 #include "ffa_private.h"
 
 /* Encoding of partition message in RX/TX buffer */
-struct ffa_part_msg_rxtx {
+struct ffa_part_msg_rxtx_1_1 {
     uint32_t flags;
     uint32_t reserved;
     uint32_t msg_offset;
@@ -21,6 +21,16 @@ struct ffa_part_msg_rxtx {
     uint32_t msg_size;
 };
 
+struct ffa_part_msg_rxtx_1_2 {
+    uint32_t flags;
+    uint32_t reserved;
+    uint32_t msg_offset;
+    uint32_t send_recv_id;
+    uint32_t msg_size;
+    uint32_t reserved2;
+    uint64_t uuid[2];
+};
+
 static void ffa_finish_direct_req_run(struct cpu_user_regs *regs,
                                       struct arm_smccc_1_2_regs *req)
 {
@@ -105,11 +115,11 @@ out:
 }
 
 static int32_t ffa_msg_send2_vm(uint16_t dst_id, const void *src_buf,
-                                struct ffa_part_msg_rxtx *src_msg)
+                                struct ffa_part_msg_rxtx_1_2 *src_msg)
 {
     struct domain *dst_d;
     struct ffa_ctx *dst_ctx;
-    struct ffa_part_msg_rxtx *dst_msg;
+    struct ffa_part_msg_rxtx_1_2 *dst_msg;
     void *rx_buf;
     size_t rx_size;
     int err;
@@ -143,7 +153,7 @@ static int32_t ffa_msg_send2_vm(uint16_t dst_id, const void *src_buf,
         goto out_unlock;
 
     /* we need to have enough space in the destination buffer */
-    if ( (rx_size - sizeof(struct ffa_part_msg_rxtx)) < src_msg->msg_size )
+    if ( (rx_size - sizeof(struct ffa_part_msg_rxtx_1_2)) < src_msg->msg_size )
     {
         ret = FFA_RET_NO_MEMORY;
         ffa_rx_release(dst_ctx);
@@ -155,11 +165,14 @@ static int32_t ffa_msg_send2_vm(uint16_t dst_id, const void *src_buf,
     /* prepare destination header */
     dst_msg->flags = 0;
     dst_msg->reserved = 0;
-    dst_msg->msg_offset = sizeof(struct ffa_part_msg_rxtx);
+    dst_msg->msg_offset = sizeof(struct ffa_part_msg_rxtx_1_2);
     dst_msg->send_recv_id = src_msg->send_recv_id;
     dst_msg->msg_size = src_msg->msg_size;
+    dst_msg->reserved2 = 0;
+    dst_msg->uuid[0] = src_msg->uuid[0];
+    dst_msg->uuid[1] = src_msg->uuid[1];
 
-    memcpy(rx_buf + sizeof(struct ffa_part_msg_rxtx),
+    memcpy(rx_buf + sizeof(struct ffa_part_msg_rxtx_1_2),
            src_buf + src_msg->msg_offset, src_msg->msg_size);
 
     /* receiver rx buffer will be released by the receiver*/
@@ -178,11 +191,17 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs)
     struct ffa_ctx *src_ctx = src_d->arch.tee;
     const void *tx_buf;
     size_t tx_size;
-    struct ffa_part_msg_rxtx src_msg;
+    /*
+     * src_msg is interpreted as v1.2 header, but:
+     * - for v1.1 guests, uuid[] is ignored and may contain payload bytes
+     * - for v1.2 guests, uuid[] carries the FF-A v1.2 UUID fields
+     */
+    struct ffa_part_msg_rxtx_1_2 src_msg;
     uint16_t dst_id, src_id;
     int32_t ret;
 
-    BUILD_BUG_ON(sizeof(struct ffa_part_msg_rxtx) >= FFA_PAGE_SIZE);
+    BUILD_BUG_ON(sizeof(struct ffa_part_msg_rxtx_1_1) >= FFA_PAGE_SIZE);
+    BUILD_BUG_ON(sizeof(struct ffa_part_msg_rxtx_1_2) >= FFA_PAGE_SIZE);
 
     ret = ffa_tx_acquire(src_ctx, &tx_buf, &tx_size);
     if ( ret != FFA_RET_OK )
@@ -194,15 +213,32 @@ int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs)
     src_id = src_msg.send_recv_id >> 16;
     dst_id = src_msg.send_recv_id & GENMASK(15,0);
 
-    if ( src_id != ffa_get_vm_id(src_d) )
+    if ( src_id != ffa_get_vm_id(src_d) ||
+         dst_id == ffa_get_vm_id(src_d) )
+    {
+        ret = FFA_RET_INVALID_PARAMETERS;
+        goto out;
+    }
+
+    if ( ACCESS_ONCE(src_ctx->guest_vers) < FFA_VERSION_1_2 )
+    {
+        if (src_msg.msg_offset < sizeof(struct ffa_part_msg_rxtx_1_1))
+        {
+            ret = FFA_RET_INVALID_PARAMETERS;
+            goto out;
+        }
+        /* Set uuid to Nil UUID for v1.1 guests */
+        src_msg.uuid[0] = 0;
+        src_msg.uuid[1] = 0;
+    }
+    else if ( src_msg.msg_offset < sizeof(struct ffa_part_msg_rxtx_1_2) )
     {
         ret = FFA_RET_INVALID_PARAMETERS;
         goto out;
     }
 
     /* check source message fits in buffer */
-    if ( src_msg.msg_offset < sizeof(struct ffa_part_msg_rxtx) ||
-            src_msg.msg_size == 0 || src_msg.msg_offset > tx_size ||
+    if ( src_msg.msg_size == 0 || src_msg.msg_offset > tx_size ||
             src_msg.msg_size > (tx_size - src_msg.msg_offset) )
     {
         ret = FFA_RET_INVALID_PARAMETERS;