hw/intc/arm_gic: Change behavior of IAR writes

Grouping (GICv2) and Security Extensions change the behavior of IAR
reads. Acknowledging Group0 interrupts is only allowed from Secure
state and acknowledging Group1 interrupts from Secure state is only
allowed if AckCtl bit is set.

Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1430502643-25909-14-git-send-email-peter.maydell@linaro.org
Message-id: 1429113742-8371-14-git-send-email-greg.bellows@linaro.org
[PMM: simplify significantly by reusing the existing
 gic_get_current_pending_irq() rather than reimplementing the
 same logic here]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/intc/arm_gic.c

@@ -213,14 +213,24 @@ static void gic_set_running_irq(GICState *s, int cpu, int irq)
     gic_update(s);
 }
 
-uint32_t gic_acknowledge_irq(GICState *s, int cpu)
+uint32_t gic_acknowledge_irq(GICState *s, int cpu, MemTxAttrs attrs)
 {
     int ret, irq, src;
     int cm = 1 << cpu;
-    irq = s->current_pending[cpu];
-    if (irq == 1023
-            || GIC_GET_PRIORITY(irq, cpu) >= s->running_priority[cpu]) {
-        DPRINTF("ACK no pending IRQ\n");
+
+    /* gic_get_current_pending_irq() will return 1022 or 1023 appropriately
+     * for the case where this GIC supports grouping and the pending interrupt
+     * is in the wrong group.
+     */
+    irq = gic_get_current_pending_irq(s, cpu, attrs);;
+
+    if (irq >= GIC_MAXIRQ) {
+        DPRINTF("ACK, no pending interrupt or it is hidden: %d\n", irq);
+        return irq;
+    }
+
+    if (GIC_GET_PRIORITY(irq, cpu) >= s->running_priority[cpu]) {
+        DPRINTF("ACK, pending interrupt (%d) has insufficient priority\n", irq);
         return 1023;
     }
     s->last_active[irq][cpu] = s->running_irq[cpu];
@@ -920,7 +930,7 @@ static MemTxResult gic_cpu_read(GICState *s, int cpu, int offset,
         }
         break;
     case 0x0c: /* Acknowledge */
-        *data = gic_acknowledge_irq(s, cpu);
+        *data = gic_acknowledge_irq(s, cpu, attrs);
         break;
     case 0x14: /* Running Priority */
         *data = gic_get_running_priority(s, cpu, attrs);

hw/intc/armv7m_nvic.c

@@ -131,7 +131,7 @@ int armv7m_nvic_acknowledge_irq(void *opaque)
     nvic_state *s = (nvic_state *)opaque;
     uint32_t irq;
 
-    irq = gic_acknowledge_irq(&s->gic, 0);
+    irq = gic_acknowledge_irq(&s->gic, 0, MEMTXATTRS_UNSPECIFIED);
     if (irq == 1023)
         hw_error("Interrupt but no vector\n");
     if (irq >= 32)

hw/intc/gic_internal.h

@@ -78,7 +78,7 @@
 #define REV_NVIC 0xffffffff
 
 void gic_set_pending_private(GICState *s, int cpu, int irq);
-uint32_t gic_acknowledge_irq(GICState *s, int cpu);
+uint32_t gic_acknowledge_irq(GICState *s, int cpu, MemTxAttrs attrs);
 void gic_complete_irq(GICState *s, int cpu, int irq, MemTxAttrs attrs);
 void gic_update(GICState *s);
 void gic_init_irqs_and_distributor(GICState *s);