[v2,4/5] xen/arm: ffa: Add indirect message between VM

Commit Message

Bertrand Marquis March 10, 2025, 2:50 p.m. UTC

Add support for indirect messages between VMs.
This is only enabled if CONFIG_FFA_VM_TO_VM is selected.

Signed-off-by: Bertrand Marquis <[e-mail]>
---
Changes in v2:
- Switch ifdef to IS_ENABLED
---
 xen/arch/arm/tee/ffa_msg.c     | 96 +++++++++++++++++++++++++++++++---
 xen/arch/arm/tee/ffa_private.h |  4 ++
 2 files changed, 92 insertions(+), 8 deletions(-)

Patch

diff --git a/xen/arch/arm/tee/ffa_msg.c b/xen/arch/arm/tee/ffa_msg.c
index ee594e737fc7..336d5bbf64f6 100644
--- a/xen/arch/arm/tee/ffa_msg.c
+++ b/xen/arch/arm/tee/ffa_msg.c
@@ -96,9 +96,6 @@  int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs)
     uint16_t dst_id, src_id;
     int32_t ret;
 
-    if ( !ffa_fw_supports_fid(FFA_MSG_SEND2) )
-        return FFA_RET_NOT_SUPPORTED;
-
     if ( !spin_trylock(&src_ctx->tx_lock) )
         return FFA_RET_BUSY;
 
@@ -106,10 +103,10 @@  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) || !FFA_ID_IS_SECURE(dst_id) )
+    if ( src_id != ffa_get_vm_id(src_d) )
     {
         ret = FFA_RET_INVALID_PARAMETERS;
-        goto out_unlock_tx;
+        goto out;
     }
 
     /* check source message fits in buffer */
@@ -118,13 +115,96 @@  int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs)
          src_msg->msg_offset < sizeof(struct ffa_part_msg_rxtx) )
     {
         ret = FFA_RET_INVALID_PARAMETERS;
-        goto out_unlock_tx;
+        goto out;
     }
 
-    ret = ffa_simple_call(FFA_MSG_SEND2,
+    if ( FFA_ID_IS_SECURE(dst_id) )
+    {
+        /* Message for a secure partition */
+        if ( !ffa_fw_supports_fid(FFA_MSG_SEND2) )
+        {
+            ret = FFA_RET_NOT_SUPPORTED;
+            goto out;
+        }
+
+        ret = ffa_simple_call(FFA_MSG_SEND2,
                           ((uint32_t)ffa_get_vm_id(src_d)) << 16, 0, 0, 0);
+        goto out;
+    }
 
-out_unlock_tx:
+    /* Message for a VM */
+    if ( IS_ENABLED(CONFIG_FFA_VM_TO_VM) )
+    {
+        struct domain *dst_d;
+        struct ffa_ctx *dst_ctx;
+        struct ffa_part_msg_rxtx *dst_msg;
+        int err;
+
+        if ( dst_id == 0 )
+        {
+            /* FF-A ID 0 is the hypervisor, this is not valid */
+            ret = FFA_RET_INVALID_PARAMETERS;
+            goto out;
+        }
+
+        /* This is also checking that dest is not src */
+        err = rcu_lock_live_remote_domain_by_id(dst_id - 1, &dst_d);
+        if ( err )
+        {
+            ret = FFA_RET_INVALID_PARAMETERS;
+            goto out;
+        }
+
+        if ( dst_d->arch.tee == NULL )
+        {
+            ret = FFA_RET_INVALID_PARAMETERS;
+            goto out_unlock;
+        }
+
+        dst_ctx = dst_d->arch.tee;
+        if ( !dst_ctx->guest_vers )
+        {
+            ret = FFA_RET_INVALID_PARAMETERS;
+            goto out_unlock;
+        }
+
+        /* This also checks that destination has set a Rx buffer */
+        ret = ffa_rx_acquire(dst_d);
+        if ( ret )
+            goto out_unlock;
+
+        /* we need to have enough space in the destination buffer */
+        if ( dst_ctx->page_count * FFA_PAGE_SIZE <
+                (sizeof(struct ffa_part_msg_rxtx) + src_msg->msg_size) )
+        {
+            ret = FFA_RET_NO_MEMORY;
+            ffa_rx_release(dst_d);
+            goto out_unlock;
+        }
+
+        dst_msg = dst_ctx->rx;
+
+        /* prepare destination header */
+        dst_msg->flags = 0;
+        dst_msg->reserved = 0;
+        dst_msg->msg_offset = sizeof(struct ffa_part_msg_rxtx);
+        dst_msg->send_recv_id = src_msg->send_recv_id;
+        dst_msg->msg_size = src_msg->msg_size;
+
+        memcpy(dst_ctx->rx + sizeof(struct ffa_part_msg_rxtx),
+               src_ctx->tx + src_msg->msg_offset, src_msg->msg_size);
+
+        /* receiver rx buffer will be released by the receiver*/
+
+out_unlock:
+        rcu_unlock_domain(dst_d);
+        if ( !ret )
+            ffa_raise_rx_buffer_full(dst_d);
+    }
+    else
+        ret = FFA_RET_INVALID_PARAMETERS;
+
+out:
     spin_unlock(&src_ctx->tx_lock);
     return ret;
 }
diff --git a/xen/arch/arm/tee/ffa_private.h b/xen/arch/arm/tee/ffa_private.h
index 1f5067d5d0c9..340db229453c 100644
--- a/xen/arch/arm/tee/ffa_private.h
+++ b/xen/arch/arm/tee/ffa_private.h
@@ -380,6 +380,10 @@  int ffa_handle_notification_set(struct cpu_user_regs *regs);
 
 #ifdef CONFIG_FFA_VM_TO_VM
 void ffa_raise_rx_buffer_full(struct domain *d);
+#else
+static inline void ffa_raise_rx_buffer_full(struct domain *d)
+{
+}
 #endif
 
 void ffa_handle_msg_send_direct_req(struct cpu_user_regs *regs, uint32_t fid);