hw/intc/arm_gic: Restrict priority view

GICs with Security Extensions restrict the non-secure view of the
interrupt priority and priority mask registers.

Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
Signed-off-by: Greg Bellows <greg.bellows@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1430502643-25909-11-git-send-email-peter.maydell@linaro.org
Message-id: 1429113742-8371-15-git-send-email-greg.bellows@linaro.org
[PMM: minor code tweaks; fixed missing masking in gic_set_priority_mask
and gic_set_priority]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 61 insertions, 7 deletions

diff --git a/hw/intc/arm_gic.c b/hw/intc/arm_gic.c
index e3bbe9e..7c0ddc8 100644
--- a/hw/intc/arm_gic.c
+++ b/hw/intc/arm_gic.c
@@ -233,8 +233,16 @@ uint32_t gic_acknowledge_irq(GICState *s, int cpu)
     return ret;
 }
 
-void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val)
+void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val,
+                      MemTxAttrs attrs)
 {
+    if (s->security_extn && !attrs.secure) {
+        if (!GIC_TEST_GROUP(irq, (1 << cpu))) {
+            return; /* Ignore Non-secure access of Group0 IRQ */
+        }
+        val = 0x80 | (val >> 1); /* Non-secure view */
+    }
+
     if (irq < GIC_INTERNAL) {
         s->priority1[irq][cpu] = val;
     } else {
@@ -242,6 +250,51 @@ void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val)
     }
 }
 
+static uint32_t gic_get_priority(GICState *s, int cpu, int irq,
+                                 MemTxAttrs attrs)
+{
+    uint32_t prio = GIC_GET_PRIORITY(irq, cpu);
+
+    if (s->security_extn && !attrs.secure) {
+        if (!GIC_TEST_GROUP(irq, (1 << cpu))) {
+            return 0; /* Non-secure access cannot read priority of Group0 IRQ */
+        }
+        prio = (prio << 1) & 0xff; /* Non-secure view */
+    }
+    return prio;
+}
+
+static void gic_set_priority_mask(GICState *s, int cpu, uint8_t pmask,
+                                  MemTxAttrs attrs)
+{
+    if (s->security_extn && !attrs.secure) {
+        if (s->priority_mask[cpu] & 0x80) {
+            /* Priority Mask in upper half */
+            pmask = 0x80 | (pmask >> 1);
+        } else {
+            /* Non-secure write ignored if priority mask is in lower half */
+            return;
+        }
+    }
+    s->priority_mask[cpu] = pmask;
+}
+
+static uint32_t gic_get_priority_mask(GICState *s, int cpu, MemTxAttrs attrs)
+{
+    uint32_t pmask = s->priority_mask[cpu];
+
+    if (s->security_extn && !attrs.secure) {
+        if (pmask & 0x80) {
+            /* Priority Mask in upper half, return Non-secure view */
+            pmask = (pmask << 1) & 0xff;
+        } else {
+            /* Priority Mask in lower half, RAZ */
+            pmask = 0;
+        }
+    }
+    return pmask;
+}
+
 static uint32_t gic_get_cpu_control(GICState *s, int cpu, MemTxAttrs attrs)
 {
     uint32_t ret = s->cpu_ctlr[cpu];
@@ -451,7 +504,7 @@ static uint32_t gic_dist_readb(void *opaque, hwaddr offset, MemTxAttrs attrs)
         irq = (offset - 0x400) + GIC_BASE_IRQ;
         if (irq >= s->num_irq)
             goto bad_reg;
-        res = GIC_GET_PRIORITY(irq, cpu);
+        res = gic_get_priority(s, cpu, irq, attrs);
     } else if (offset < 0xc00) {
         /* Interrupt CPU Target.  */
         if (s->num_cpu == 1 && s->revision != REV_11MPCORE) {
@@ -669,7 +722,7 @@ static void gic_dist_writeb(void *opaque, hwaddr offset,
         irq = (offset - 0x400) + GIC_BASE_IRQ;
         if (irq >= s->num_irq)
             goto bad_reg;
-        gic_set_priority(s, cpu, irq, value);
+        gic_set_priority(s, cpu, irq, value, attrs);
     } else if (offset < 0xc00) {
         /* Interrupt CPU Target. RAZ/WI on uniprocessor GICs, with the
          * annoying exception of the 11MPCore's GIC.
@@ -820,7 +873,7 @@ static MemTxResult gic_cpu_read(GICState *s, int cpu, int offset,
         *data = gic_get_cpu_control(s, cpu, attrs);
         break;
     case 0x04: /* Priority mask */
-        *data = s->priority_mask[cpu];
+        *data = gic_get_priority_mask(s, cpu, attrs);
         break;
     case 0x08: /* Binary Point */
         if (s->security_extn && !attrs.secure) {
@@ -870,7 +923,7 @@ static MemTxResult gic_cpu_write(GICState *s, int cpu, int offset,
         gic_set_cpu_control(s, cpu, value, attrs);
         break;
     case 0x04: /* Priority mask */
-        s->priority_mask[cpu] = (value & 0xff);
+        gic_set_priority_mask(s, cpu, value, attrs);
         break;
     case 0x08: /* Binary Point */
         if (s->security_extn && !attrs.secure) {
diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
index 33e6a87..2cb7d25 100644
--- a/hw/intc/arm_gic_kvm.c
+++ b/hw/intc/arm_gic_kvm.c
@@ -251,7 +251,7 @@ static void translate_priority(GICState *s, int irq, int cpu,
     if (to_kernel) {
         *field = GIC_GET_PRIORITY(irq, cpu) & 0xff;
     } else {
-        gic_set_priority(s, cpu, irq, *field & 0xff);
+        gic_set_priority(s, cpu, irq, *field & 0xff, MEMTXATTRS_UNSPECIFIED);
     }
 }
 
diff --git a/hw/intc/gic_internal.h b/hw/intc/gic_internal.h
index 81c764c..119fb81 100644
--- a/hw/intc/gic_internal.h
+++ b/hw/intc/gic_internal.h
@@ -82,7 +82,8 @@ uint32_t gic_acknowledge_irq(GICState *s, int cpu);
 void gic_complete_irq(GICState *s, int cpu, int irq);
 void gic_update(GICState *s);
 void gic_init_irqs_and_distributor(GICState *s);
-void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val);
+void gic_set_priority(GICState *s, int cpu, int irq, uint8_t val,
+                      MemTxAttrs attrs);
 
 static inline bool gic_test_pending(GICState *s, int irq, int cm)
 {