hw/intc: ibex_plic: Don't allow repeat interrupts on claimed lines

Once an interrupt has been claimed, but before it has been compelted we
shouldn't receive any more pending interrupts. This patche keeps track
of this to ensure that we don't see any more interrupts until it is
completed.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <394c3f070615ff2b4fab61a1cf9cb48c122913b7.1595655188.git.alistair.francis@wdc.com>

diff --git a/hw/intc/ibex_plic.c b/hw/intc/ibex_plic.c
index 578edd2ce0248844b46b5c5b2c3f0d602d843cf4..669247ef08df98d3124ff4a3de7913573a6ba090 100644 (file)
--- a/hw/intc/ibex_plic.c
+++ b/hw/intc/ibex_plic.c
@@ -43,6 +43,14 @@ static void ibex_plic_irqs_set_pending(IbexPlicState *s, int irq, bool level)
 {
     int pending_num = irq / 32;
 
+    if (s->claimed[pending_num] & 1 << (irq % 32)) {
+        /*
+         * The interrupt has been claimed, but not compelted.
+         * The pending bit can't be set.
+         */
+        return;
+    }
+
     s->pending[pending_num] |= level << (irq % 32);
 }
 
@@ -120,6 +128,10 @@ static uint64_t ibex_plic_read(void *opaque, hwaddr addr,
         int pending_num = s->claim / 32;
         s->pending[pending_num] &= ~(1 << (s->claim % 32));
 
+        /* Set the interrupt as claimed, but not compelted */
+        s->claimed[pending_num] |= 1 << (s->claim % 32);
+
+        /* Return the current claimed interrupt */
         ret = s->claim;
 
         /* Update the interrupt status after the claim */
@@ -155,6 +167,10 @@ static void ibex_plic_write(void *opaque, hwaddr addr,
             /* Interrupt was completed */
             s->claim = 0;
         }
+        if (s->claimed[value / 32] & 1 << (value % 32)) {
+            /* This value was already claimed, clear it. */
+            s->claimed[value / 32] &= ~(1 << (value % 32));
+        }
     }
 
     ibex_plic_update(s);
@@ -215,6 +231,7 @@ static void ibex_plic_realize(DeviceState *dev, Error **errp)
     int i;
 
     s->pending = g_new0(uint32_t, s->pending_num);
+    s->claimed = g_new0(uint32_t, s->pending_num);
     s->source = g_new0(uint32_t, s->source_num);
     s->priority = g_new0(uint32_t, s->priority_num);
     s->enable = g_new0(uint32_t, s->enable_num);

diff --git a/include/hw/intc/ibex_plic.h b/include/hw/intc/ibex_plic.h
index ddc7909903a8c7160efe44a0dc90a9bbb3333fbe..d8eb09b258a08fef27a0b3c2c1228c25f091239e 100644 (file)
--- a/include/hw/intc/ibex_plic.h
+++ b/include/hw/intc/ibex_plic.h
@@ -33,6 +33,7 @@ typedef struct IbexPlicState {
     MemoryRegion mmio;
 
     uint32_t *pending;
+    uint32_t *claimed;
     uint32_t *source;
     uint32_t *priority;
     uint32_t *enable;