[xen staging] xen/arm: ffa: Add buffer full notification support

[patchbot@xxxxxxx]

commit 3935c705688e5958bb30d3f061fca660191be693
Author:     Bertrand Marquis <bertrand.marquis@xxxxxxx>
AuthorDate: Mon Aug 11 15:35:00 2025 +0200
Commit:     Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Tue Aug 12 12:04:41 2025 +0100

    xen/arm: ffa: Add buffer full notification support
    
    Add support to raise a Rx buffer full notification to a VM.
    This function will be used for indirect message support between VM and
    is only activated if CONFIG_FFA_VM_TO_VM is selected.
    
    Even if there are 32 framework notifications possible, right now only
    one is defined so the implementation is simplified to only handle the
    buffer full notification using a boolean. If other framework
    notifications have to be supported one day, the design will have to be
    modified to handle it properly.
    
    Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
    Reviewed-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
    Acked-by: Julien Grall <jgrall@xxxxxxxxxx>
---
 xen/arch/arm/tee/ffa_notif.c   | 36 ++++++++++++++++++++++++++++++------
 xen/arch/arm/tee/ffa_private.h | 23 ++++++++++++++++++++++-
 2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/tee/ffa_notif.c b/xen/arch/arm/tee/ffa_notif.c
index 00efaf8f73..f6df2f15bb 100644
--- a/xen/arch/arm/tee/ffa_notif.c
+++ b/xen/arch/arm/tee/ffa_notif.c
@@ -69,6 +69,7 @@ void ffa_handle_notification_info_get(struct cpu_user_regs 
*regs)
 {
     struct domain *d = current->domain;
     struct ffa_ctx *ctx = d->arch.tee;
+    bool notif_pending;
 
     if ( !notif_enabled )
     {
@@ -76,7 +77,11 @@ void ffa_handle_notification_info_get(struct cpu_user_regs 
*regs)
         return;
     }
 
-    if ( test_and_clear_bool(ctx->notif.secure_pending) )
+    notif_pending = test_and_clear_bool(ctx->notif.secure_pending);
+    if ( IS_ENABLED(CONFIG_FFA_VM_TO_VM) )
+        notif_pending |= test_and_clear_bool(ctx->notif.vm_pending);
+
+    if ( notif_pending )
     {
         /* A pending global notification for the guest */
         ffa_set_regs(regs, FFA_SUCCESS_64, 0,
@@ -93,6 +98,7 @@ void ffa_handle_notification_info_get(struct cpu_user_regs 
*regs)
 void ffa_handle_notification_get(struct cpu_user_regs *regs)
 {
     struct domain *d = current->domain;
+    struct ffa_ctx *ctx = d->arch.tee;
     uint32_t recv = get_user_reg(regs, 1);
     uint32_t flags = get_user_reg(regs, 2);
     uint32_t w2 = 0;
@@ -132,11 +138,7 @@ void ffa_handle_notification_get(struct cpu_user_regs 
*regs)
          */
         if ( ( flags  & FFA_NOTIF_FLAG_BITMAP_SP ) &&
              ( flags & FFA_NOTIF_FLAG_BITMAP_SPM ) )
-        {
-                struct ffa_ctx *ctx = d->arch.tee;
-
-                ACCESS_ONCE(ctx->notif.secure_pending) = false;
-        }
+            ACCESS_ONCE(ctx->notif.secure_pending) = false;
 
         arm_smccc_1_2_smc(&arg, &resp);
         e = ffa_get_ret_code(&resp);
@@ -156,6 +158,14 @@ void ffa_handle_notification_get(struct cpu_user_regs 
*regs)
             w6 = resp.a6;
     }
 
+    if ( IS_ENABLED(CONFIG_FFA_VM_TO_VM) &&
+          flags & FFA_NOTIF_FLAG_BITMAP_HYP &&
+          test_and_clear_bool(ctx->notif.buff_full_pending) )
+    {
+        ACCESS_ONCE(ctx->notif.vm_pending) = false;
+        w7 = FFA_NOTIF_RX_BUFFER_FULL;
+    }
+
     ffa_set_regs(regs, FFA_SUCCESS_32, 0, w2, w3, w4, w5, w6, w7);
 }
 
@@ -178,6 +188,20 @@ int ffa_handle_notification_set(struct cpu_user_regs *regs)
                            bitmap_hi);
 }
 
+#ifdef CONFIG_FFA_VM_TO_VM
+void ffa_raise_rx_buffer_full(struct domain *d)
+{
+    struct ffa_ctx *ctx = d->arch.tee;
+
+    if ( !ctx )
+        return;
+
+    ACCESS_ONCE(ctx->notif.buff_full_pending) = true;
+    if ( !test_and_set_bool(ctx->notif.vm_pending) )
+        vgic_inject_irq(d, d->vcpu[0], GUEST_FFA_NOTIF_PEND_INTR_ID, true);
+}
+#endif
+
 /*
  * Extract a 16-bit ID (index n) from the successful return value from
  * FFA_NOTIFICATION_INFO_GET_64 or FFA_NOTIFICATION_INFO_GET_32. IDs are
diff --git a/xen/arch/arm/tee/ffa_private.h b/xen/arch/arm/tee/ffa_private.h
index 5cb2b51714..6dbdb200d8 100644
--- a/xen/arch/arm/tee/ffa_private.h
+++ b/xen/arch/arm/tee/ffa_private.h
@@ -218,6 +218,8 @@
 #define FFA_NOTIF_INFO_GET_ID_COUNT_SHIFT   7
 #define FFA_NOTIF_INFO_GET_ID_COUNT_MASK    0x1F
 
+#define FFA_NOTIF_RX_BUFFER_FULL        BIT(0, U)
+
 /* Feature IDs used with FFA_FEATURES */
 #define FFA_FEATURE_NOTIF_PEND_INTR     0x1U
 #define FFA_FEATURE_SCHEDULE_RECV_INTR  0x2U
@@ -303,9 +305,20 @@ struct ffa_mem_region {
 struct ffa_ctx_notif {
     /*
      * True if domain is reported by FFA_NOTIFICATION_INFO_GET to have
-     * pending global notifications.
+     * pending notifications from the secure world.
      */
     bool secure_pending;
+
+    /*
+     * True if domain is reported by FFA_NOTIFICATION_INFO_GET to have
+     * pending notifications from VMs (including framework ones).
+     */
+    bool vm_pending;
+
+    /*
+     * True if domain has buffer full notification pending
+     */
+    bool buff_full_pending;
 };
 
 struct ffa_ctx {
@@ -419,6 +432,14 @@ void ffa_handle_notification_info_get(struct cpu_user_regs 
*regs);
 void ffa_handle_notification_get(struct cpu_user_regs *regs);
 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);
 int32_t ffa_handle_msg_send2(struct cpu_user_regs *regs);
 
--
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