[PATCH 1/3] arm_gic: Mask the un-supported priority bits

[Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>]

Priority bits implemented in arm-gic can 8 to 4, un-implemented bits
are read as zeros(RAZ).

Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
---
 hw/intc/arm_gic.c                | 9 ++++++---
 hw/intc/arm_gic_common.c         | 1 +
 include/hw/intc/arm_gic_common.h | 1 +
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index 1d7da7b..8875330 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -43,6 +43,9 @@
         }                                                               \
     } while (0)
 
+#define UMASK(n) \
+    ((((1 << n) - 1) << (8 - n)) & 0xFF)
+
 static const uint8_t gic_id_11mpcore[] = {
     0x00, 0x00, 0x00, 0x00, 0x90, 0x13, 0x04, 0x00, 0x0d, 0xf0, 0x05, 0xb1
 };
@@ -652,9 +655,9 @@ void gic_dist_set_priority(GICState *s, int cpu, int irq, uint8_t val,
     }
 
     if (irq < GIC_INTERNAL) {
-        s->priority1[irq][cpu] = val;
+        s->priority1[irq][cpu] = val & UMASK(s->n_prio_bits) ;
     } else {
-        s->priority2[(irq) - GIC_INTERNAL] = val;
+        s->priority2[(irq) - GIC_INTERNAL] = val & UMASK(s->n_prio_bits);
     }
 }
 
@@ -684,7 +687,7 @@ static void gic_set_priority_mask(GICState *s, int cpu, uint8_t pmask,
             return;
         }
     }
-    s->priority_mask[cpu] = pmask;
+    s->priority_mask[cpu] = pmask & UMASK(s->n_prio_bits);
 }
 
 static uint32_t gic_get_priority_mask(GICState *s, int cpu, MemTxAttrs attrs)
diff --git a/hw/intc/arm_gic_common.c b/hw/intc/arm_gic_common.c
index e6c4fe7..e4668c7 100644
--- a/hw/intc/arm_gic_common.c
+++ b/hw/intc/arm_gic_common.c
@@ -357,6 +357,7 @@ static Property arm_gic_common_properties[] = {
     DEFINE_PROP_BOOL("has-security-extensions", GICState, security_extn, 0),
     /* True if the GIC should implement the virtualization extensions */
     DEFINE_PROP_BOOL("has-virtualization-extensions", GICState, virt_extn, 0),
+    DEFINE_PROP_UINT32("num-prio-bits", GICState, n_prio_bits, 8),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/intc/arm_gic_common.h b/include/hw/intc/arm_gic_common.h
index b5585fe..6e0d6b8 100644
--- a/include/hw/intc/arm_gic_common.h
+++ b/include/hw/intc/arm_gic_common.h
@@ -96,6 +96,7 @@ typedef struct GICState {
     uint16_t priority_mask[GIC_NCPU_VCPU];
     uint16_t running_priority[GIC_NCPU_VCPU];
     uint16_t current_pending[GIC_NCPU_VCPU];
+    uint32_t n_prio_bits;
 
     /* If we present the GICv2 without security extensions to a guest,
      * the guest can configure the GICC_CTLR to configure group 1 binary point
-- 
2.7.4