[Qemu-devel] [PATCH 6/9] hw/arm_gic: Make CPU target registers RAZ/WI on uniprocessor

[Peter Maydell <peter.maydell@linaro.org>]

The GIC spec says that the CPU target registers should RAZ/WI
for uniprocessor implementations. Implement this, which also
conveniently lets us drop an NVIC ifdef.

Annoyingly, the 11MPCore's GIC is the odd one out, since
it always has these registers, even in uniprocessor configs.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm_gic.c |   56 +++++++++++++++++++++++++++++++++-----------------------
 1 files changed, 33 insertions(+), 23 deletions(-)

diff --git a/hw/arm_gic.c b/hw/arm_gic.c
index ad72ac6..a6e2431 100644
--- a/hw/arm_gic.c
+++ b/hw/arm_gic.c
@@ -86,11 +86,7 @@ typedef struct gic_irq_state
 #define GIC_GET_PRIORITY(irq, cpu) (((irq) < GIC_INTERNAL) ?            \
                                     s->priority1[irq][cpu] :            \
                                     s->priority2[(irq) - GIC_INTERNAL])
-#ifdef NVIC
-#define GIC_TARGET(irq) 1
-#else
 #define GIC_TARGET(irq) s->irq_target[irq]
-#endif
 
 typedef struct gic_state
 {
@@ -377,18 +373,22 @@ static uint32_t gic_dist_readb(void *opaque, target_phys_addr_t offset)
         if (irq >= s->num_irq)
             goto bad_reg;
         res = GIC_GET_PRIORITY(irq, cpu);
-#ifndef NVIC
     } else if (offset < 0xc00) {
         /* Interrupt CPU Target.  */
-        irq = (offset - 0x800) + GIC_BASE_IRQ;
-        if (irq >= s->num_irq)
-            goto bad_reg;
-        if (irq >= 29 && irq <= 31) {
-            res = cm;
+        if (s->num_cpu == 1 && s->revision != REV_11MPCORE) {
+            /* For uniprocessor GICs these RAZ/WI */
+            res = 0;
         } else {
-            res = GIC_TARGET(irq);
+            irq = (offset - 0x800) + GIC_BASE_IRQ;
+            if (irq >= s->num_irq) {
+                goto bad_reg;
+            }
+            if (irq >= 29 && irq <= 31) {
+                res = cm;
+            } else {
+                res = GIC_TARGET(irq);
+            }
         }
-#endif
     } else if (offset < 0xf00) {
         /* Interrupt Configuration.  */
         irq = (offset - 0xc00) * 2 + GIC_BASE_IRQ;
@@ -533,18 +533,22 @@ static void gic_dist_writeb(void *opaque, target_phys_addr_t offset,
         } else {
             s->priority2[irq - GIC_INTERNAL] = value;
         }
-#ifndef NVIC
     } else if (offset < 0xc00) {
-        /* Interrupt CPU Target.  */
-        irq = (offset - 0x800) + GIC_BASE_IRQ;
-        if (irq >= s->num_irq)
-            goto bad_reg;
-        if (irq < 29)
-            value = 0;
-        else if (irq < GIC_INTERNAL)
-            value = ALL_CPU_MASK;
-        s->irq_target[irq] = value & ALL_CPU_MASK;
-#endif
+        /* Interrupt CPU Target. RAZ/WI on uniprocessor GICs, with the
+         * annoying exception of the 11MPCore's GIC.
+         */
+        if (s->num_cpu != 1 || s->revision == REV_11MPCORE) {
+            irq = (offset - 0x800) + GIC_BASE_IRQ;
+            if (irq >= s->num_irq) {
+                goto bad_reg;
+            }
+            if (irq < 29) {
+                value = 0;
+            } else if (irq < GIC_INTERNAL) {
+                value = ALL_CPU_MASK;
+            }
+            s->irq_target[irq] = value & ALL_CPU_MASK;
+        }
     } else if (offset < 0xf00) {
         /* Interrupt Configuration.  */
         irq = (offset - 0xc00) * 4 + GIC_BASE_IRQ;
@@ -733,6 +737,12 @@ static void gic_reset(DeviceState *dev)
         GIC_SET_ENABLED(i, ALL_CPU_MASK);
         GIC_SET_TRIGGER(i);
     }
+    if (s->num_cpu == 1) {
+        /* For uniprocessor GICs all interrupts always target the sole CPU */
+        for (i = 0; i < GIC_MAXIRQ; i++) {
+            s->irq_target[i] = 1;
+        }
+    }
     s->enabled = 0;
 }
 
-- 
1.7.1