[RFC PATCH] hw/intc/arm_gic: handle Set-Active/Clear-Active registers

["Alex Bennée" <alex.bennee@linaro.org>]

I noticed while testing with modern kernels and -d guest_errors warnings
about invalid writes to the GIC. For GICv2 these registers certainly
should work so I've implemented both. As the code is common between all
the various GICs writes to GICD_ISACTIVERn is checked to ensure it is
not a RO register for v1 GICs.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 hw/intc/arm_gic.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index b30cc91..423a4ae 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -972,9 +972,38 @@ static void gic_dist_writeb(void *opaque, hwaddr offset,
                 GIC_CLEAR_PENDING(irq + i, ALL_CPU_MASK);
             }
         }
+    } else if (offset < 0x380) {
+        /* Interrupt Set-Active */
+        irq = (offset - 0x300) * 8 + GIC_BASE_IRQ;
+        if (irq >= s->num_irq || s->revision < 2)
+            goto bad_reg;
+
+        for (i = 0; i < 8; i++) {
+            if (s->security_extn && !attrs.secure &&
+                !GIC_TEST_GROUP(irq + i, 1 << cpu)) {
+                continue; /* Ignore Non-secure access of Group0 IRQ */
+            }
+
+            if (value & (1 << i)) {
+                GIC_SET_ACTIVE(irq + i, 1 << cpu);
+            }
+        }
     } else if (offset < 0x400) {
-        /* Interrupt Active.  */
-        goto bad_reg;
+        /* Interrupt Clear-Active  */
+        irq = (offset - 0x380) * 8 + GIC_BASE_IRQ;
+        if (irq >= s->num_irq)
+            goto bad_reg;
+
+        for (i = 0; i < 8; i++) {
+            if (s->security_extn && !attrs.secure &&
+                !GIC_TEST_GROUP(irq + i, 1 << cpu)) {
+                continue; /* Ignore Non-secure access of Group0 IRQ */
+            }
+
+            if (value & (1 << i)) {
+                GIC_CLEAR_ACTIVE(irq + i, 1 << cpu);
+            }
+        }
     } else if (offset < 0x800) {
         /* Interrupt Priority.  */
         irq = (offset - 0x400) + GIC_BASE_IRQ;
-- 
2.9.3