[Qemu-devel] [PATCH v2 13/16] hw/intc/arm_gic: Change behavior of IAR writes

[Greg Bellows <greg.bellows@linaro.org>]

From: Fabian Aggeler <aggelerf@ethz.ch>

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>

---

v1 -> v2
- Fix issue in gic_acknowledge_irq() where the GICC_CTLR_S_ACK_CTL flag is
  applied without first checking whether the read is secure or non-secure.
  Secure reads of IAR when AckCtl is 0 return a spurious ID of 1022, but
  non-secure ignores the flag.
---
 hw/intc/arm_gic.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index 2d83225..7eb72df 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -190,11 +190,36 @@ uint32_t gic_acknowledge_irq(GICState *s, int cpu)
     int ret, irq, src;
     int cm = 1 << cpu;
     irq = s->current_pending[cpu];
+    bool isGrp0;
     if (irq == 1023
             || GIC_GET_PRIORITY(irq, cpu) >= s->running_priority[cpu]) {
         DPRINTF("ACK no pending IRQ\n");
         return 1023;
     }
+
+    if (s->revision >= 2 || s->security_extn) {
+        isGrp0 = GIC_TEST_GROUP0(irq, (1 << cpu));
+        if ((isGrp0 && (!s->enabled_grp[0]
+                    || !(s->cpu_control[cpu][0] & GICC_CTLR_S_EN_GRP0)))
+           || (!isGrp0 && (!s->enabled_grp[1]
+                    || !(s->cpu_control[cpu][1] & GICC_CTLR_NS_EN_GRP1)))) {
+            return 1023;
+        }
+
+        if ((s->revision >= 2 && !s->security_extn)
+                || (s->security_extn && !ns_access())) {
+            if (!isGrp0 && !ns_access() &&
+                !(s->cpu_control[cpu][0] & GICC_CTLR_S_ACK_CTL)) {
+                DPRINTF("Read of IAR ignored for Group1 interrupt %d "
+                        "(AckCtl disabled)\n", irq);
+                return 1022;
+            }
+        } else if (s->security_extn && ns_access() && isGrp0) {
+            DPRINTF("Non-secure read of IAR ignored for Group0 interrupt %d\n",
+                    irq);
+            return 1023;
+        }
+    }
     s->last_active[irq][cpu] = s->running_irq[cpu];
 
     if (s->revision == REV_11MPCORE || s->revision == REV_NVIC) {
-- 
1.8.3.2