[Qemu-devel] [PATCH v3 07/16] hw/intc/arm_gic: Make ICDDCR/GICD_CTLR banked

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

From: Fabian Aggeler <aggelerf@ethz.ch>

ICDDCR/GICD_CTLR is banked in GICv1 implementations with Security
Extensions or in GICv2 in independent from Security Extensions.
This makes it possible to enable forwarding of interrupts from
Distributor to the CPU interfaces for Group0 and Group1.

EnableGroup0 (Bit [1]) in GICv1 is IMPDEF. Since this bit (Enable
Non-secure) is present in the integrated IC of the Cortex-A9 MPCore,
which implements the GICv1 profile, we support this bit in GICv1 too.

Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
Signed-off-by: Greg Bellows <greg.bellows@linaro.org>

---
v2 -> v3
- Added missing return in gic_dist_readb()
- Fixed typos

v1 -> v2
- Fix gic_dist_writeb() update of GICD_CTRL to only use bit[0] of the
  EnableGrp1 field not bit[1].
- Add clarifying comments
---
 hw/intc/arm_gic.c                | 50 ++++++++++++++++++++++++++++++++++++----
 hw/intc/arm_gic_common.c         |  2 +-
 include/hw/intc/arm_gic_common.h |  7 +++++-
 3 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index aa4402e..b9dfde3 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -302,8 +302,26 @@ static uint32_t gic_dist_readb(void *opaque, hwaddr offset)
     cpu = gic_get_current_cpu(s);
     cm = 1 << cpu;
     if (offset < 0x100) {
-        if (offset == 0)
-            return s->enabled;
+        if (offset == 0) {      /* GICD_CTLR */
+            res = 0;
+            if ((s->revision == 2 && !s->security_extn)
+                    || (s->security_extn && !ns_access())) {
+                /* In this case the GICD_CTLR contains both a group0 and group1
+                 * enable bit, so we create the resuling value by aggregating
+                 * the bits from the two enable values.
+                 * The group0 enable bit is only visible to secure accesses.
+                 * The group1 enable bit (bit[1]) is an alias of bit[0] in
+                 * the non-secure copy (enabled_grp[1]).
+                 */
+                res = (s->enabled_grp[1] << 1) | s->enabled_grp[0];
+            } else if (s->security_extn && ns_access()) {
+                res = s->enabled_grp[1];
+            } else {
+                /* Neither GICv2 nor Security Extensions present */
+                res = s->enabled;
+            }
+            return res;
+        }
         if (offset == 4)
             /* Interrupt Controller Type Register */
             return ((s->num_irq / 32) - 1)
@@ -471,8 +489,32 @@ static void gic_dist_writeb(void *opaque, hwaddr offset,
     cpu = gic_get_current_cpu(s);
     if (offset < 0x100) {
         if (offset == 0) {
-            s->enabled = (value & 1);
-            DPRINTF("Distribution %sabled\n", s->enabled ? "En" : "Dis");
+            if ((s->revision == 2 && !s->security_extn)
+                    || (s->security_extn && !ns_access())) {
+                s->enabled_grp[0] = value & (1U << 0); /* EnableGrp0 */
+                /* For a GICv1 with Security Extn "EnableGrp1" is IMPDEF. */
+                /* We only use the first bit of the enabled_grp vars to
+                 * indicate enabled or disabled.  In this case we have to shift
+                 * the incoming value down to the low bit because the group1
+                 * enabled bit is bit[1] in the secure/GICv2 GICD_CTLR.
+                 */
+                s->enabled_grp[1] = (value >> 1) & 0x1; /* EnableGrp1 */
+                DPRINTF("Group0 distribution %sabled\n"
+                        "Group1 distribution %sabled\n",
+                                        s->enabled_grp[0] ? "En" : "Dis",
+                                        s->enabled_grp[1] ? "En" : "Dis");
+            } else if (s->security_extn && ns_access()) {
+                /* If we are non-secure only the group1 enable bit is visible
+                 * as bit[0] in the GICD_CTLR.
+                 */
+                s->enabled_grp[1] = (value & 0x1);
+                DPRINTF("Group1 distribution %sabled\n",
+                        s->enabled_grp[1] ? "En" : "Dis");
+            } else {
+                /* Neither GICv2 nor Security Extensions present */
+                s->enabled = (value & 0x1);
+                DPRINTF("Distribution %sabled\n", s->enabled ? "En" : "Dis");
+            }
         } else if (offset < 4) {
             /* ignored.  */
         } else if (offset >= 0x80) {
diff --git a/hw/intc/arm_gic_common.c b/hw/intc/arm_gic_common.c
index 28f3b2a..c44050d 100644
--- a/hw/intc/arm_gic_common.c
+++ b/hw/intc/arm_gic_common.c
@@ -64,7 +64,7 @@ static const VMStateDescription vmstate_gic = {
     .pre_save = gic_pre_save,
     .post_load = gic_post_load,
     .fields = (VMStateField[]) {
-        VMSTATE_BOOL(enabled, GICState),
+        VMSTATE_UINT8_ARRAY(enabled_grp, GICState, GIC_NR_GROUP),
         VMSTATE_BOOL_ARRAY(cpu_enabled, GICState, GIC_NCPU),
         VMSTATE_STRUCT_ARRAY(irq_state, GICState, GIC_MAXIRQ, 1,
                              vmstate_gic_irq_state, gic_irq_state),
diff --git a/include/hw/intc/arm_gic_common.h b/include/hw/intc/arm_gic_common.h
index b78981e..16e193d 100644
--- a/include/hw/intc/arm_gic_common.h
+++ b/include/hw/intc/arm_gic_common.h
@@ -30,6 +30,8 @@
 #define GIC_NR_SGIS 16
 /* Maximum number of possible CPU interfaces, determined by GIC architecture */
 #define GIC_NCPU 8
+/* Number of Groups (Group0 [Secure], Group1 [Non-secure]) */
+#define GIC_NR_GROUP 2
 
 #define MAX_NR_GROUP_PRIO 128
 #define GIC_NR_APRS (MAX_NR_GROUP_PRIO / 32)
@@ -52,7 +54,10 @@ typedef struct GICState {
 
     qemu_irq parent_irq[GIC_NCPU];
     qemu_irq parent_fiq[GIC_NCPU];
-    bool enabled;
+    union {
+        uint8_t enabled;
+        uint8_t enabled_grp[GIC_NR_GROUP]; /* EnableGrp0 and EnableGrp1 */
+    };
     bool cpu_enabled[GIC_NCPU];
 
     gic_irq_state irq_state[GIC_MAXIRQ];
-- 
1.8.3.2