lib: Improve delivery of SBI_IPI_EVENT_HALT

When sbi_ipi_send_many gets called with the current hartid
included on pmask (or when pmask is NULL), and we send
a HALT event, since the for loop works sequentially over
all hartids on the mask, we may send a HALT event to the
current hart before the loop finishes. So we will halt
the current hart before it can deliver a HALT IPI to the
rest and some harts will remain active.

Make sure we send an IPI to the current hart after we've
finished with everybody else.

Signed-off-by: Nick Kossifidis <mick@ics.forth.gr>

diff --git a/lib/sbi_ipi.c b/lib/sbi_ipi.c
index 0e9fb30..aeca71c 100644 (file)
--- a/lib/sbi_ipi.c
+++ b/lib/sbi_ipi.c
@@ -5,6 +5,7 @@
  *
  * Authors:
  *   Anup Patel <anup.patel@wdc.com>
+ *   Nick Kossifidis <mick@ics.forth.gr
  */
 
 #include <sbi/riscv_asm.h>
@@ -18,28 +19,48 @@
 #include <sbi/sbi_timer.h>
 #include <sbi/sbi_unpriv.h>
 
+static int sbi_ipi_send(struct sbi_scratch *scratch, u32 hartid, u32 event)
+{
+       struct sbi_scratch *remote_scratch = NULL;
+       struct sbi_platform *plat = sbi_platform_ptr(scratch);
+
+       if (sbi_platform_hart_disabled(plat, hartid))
+               return -1;
+
+       /* Set IPI type on remote hart's scratch area and
+        * trigger the interrupt
+        */
+       remote_scratch = sbi_hart_id_to_scratch(scratch, hartid);
+       atomic_raw_set_bit(event, &remote_scratch->ipi_type);
+       mb();
+       sbi_platform_ipi_send(plat, hartid);
+       if (event != SBI_IPI_EVENT_SOFT)
+               sbi_platform_ipi_sync(plat, hartid);
+
+       return 0;
+}
+
 int sbi_ipi_send_many(struct sbi_scratch *scratch,
                      ulong *pmask, u32 event)
 {
        ulong i, m;
-       struct sbi_scratch *oth;
        ulong mask = sbi_hart_available_mask();
-       struct sbi_platform *plat = sbi_platform_ptr(scratch);
+       u32 hartid = sbi_current_hartid();
 
        if (pmask)
                mask &= load_ulong(pmask, csr_read(CSR_MEPC));
 
-       /* send IPIs to everyone */
-       for (i = 0, m = mask; m; i++, m >>= 1) {
-               if ((m & 1) && !sbi_platform_hart_disabled(plat, i)) {
-                       oth = sbi_hart_id_to_scratch(scratch, i);
-                       atomic_raw_set_bit(event, &oth->ipi_type);
-                       mb();
-                       sbi_platform_ipi_send(plat, i);
-                       if (event != SBI_IPI_EVENT_SOFT)
-                               sbi_platform_ipi_sync(plat, i);
-               }
-       }
+       /* send IPIs to every other hart on the set */
+       for (i = 0, m = mask; m > 0; m >>= ++i)
+               if ((m & 1UL) && (i != hartid))
+                       sbi_ipi_send(scratch, i, event);
+
+       /* If the current hart is on the set, send an IPI
+        * to it as well
+        */
+       if (mask & (1UL << hartid))
+               sbi_ipi_send(scratch, hartid, event);
+
 
        return 0;
 }