[Qemu-arm] [PATCH for-2.12] hw/intc/arm_gicv3: Fix secure-GIC NS ICC_PMR and ICC_RPR accesses

[Peter Maydell]

If the GIC has the security extension support enabled, then a
non-secure access to ICC_PMR must take account of the non-secure
view of interrupt priorities, where real priorities 0..0x7f
are secure-only and not visible to the non-secure guest, and
priorities 0x80..0xff are shown to the guest as if they were
0x00..0xff. We had the logic here wrong:
 * on reads, the priority is in the secure range if bit 7
   is clear, not if it is set
 * on writes, we want to set bit 7, not mask everything else

Our ICC_RPR read code had the same error as ICC_PMR.

(Compare the GICv3 spec pseudocode functions ICC_RPR_EL1
and ICC_PMR_EL1.)

Fixes: https://bugs.launchpad.net/qemu/+bug/1748434
Signed-off-by: Peter Maydell <address@hidden>
---
 hw/intc/arm_gicv3_cpuif.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/intc/arm_gicv3_cpuif.c b/hw/intc/arm_gicv3_cpuif.c
index 5cbafaf497..26f5eeda94 100644
--- a/hw/intc/arm_gicv3_cpuif.c
+++ b/hw/intc/arm_gicv3_cpuif.c
@@ -836,7 +836,7 @@ static uint64_t icc_pmr_read(CPUARMState *env, const 
ARMCPRegInfo *ri)
         /* NS access and Group 0 is inaccessible to NS: return the
          * NS view of the current priority
          */
-        if (value & 0x80) {
+        if ((value & 0x80) == 0) {
             /* Secure priorities not visible to NS */
             value = 0;
         } else if (value != 0xff) {
@@ -871,7 +871,7 @@ static void icc_pmr_write(CPUARMState *env, const 
ARMCPRegInfo *ri,
             /* Current PMR in the secure range, don't allow NS to change it */
             return;
         }
-        value = (value >> 1) & 0x80;
+        value = (value >> 1) | 0x80;
     }
     cs->icc_pmr_el1 = value;
     gicv3_cpuif_update(cs);
@@ -1609,7 +1609,7 @@ static uint64_t icc_rpr_read(CPUARMState *env, const 
ARMCPRegInfo *ri)
     if (arm_feature(env, ARM_FEATURE_EL3) &&
         !arm_is_secure(env) && (env->cp15.scr_el3 & SCR_FIQ)) {
         /* NS GIC access and Group 0 is inaccessible to NS */
-        if (prio & 0x80) {
+        if ((prio & 0x80) == 0) {
             /* NS mustn't see priorities in the Secure half of the range */
             prio = 0;
         } else if (prio != 0xff) {
-- 
2.16.2