target/arm/helper: Implement CNTHCTL_EL2.CNT[VP]MASK

When FEAT_RME is implemented, these bits override the value of
CNT[VP]_CTL_EL0.IMASK in Realm and Root state. Move the IRQ state update
into a new gt_update_irq() function and test those bits every time we
recompute the IRQ state.

Since we're removing the IRQ state from some trace events, add a new
trace event for gt_update_irq().

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Message-id: 20230809123706.1842548-7-jean-philippe@linaro.org
[PMM: only register change hook if not USER_ONLY and if TCG]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 54 insertions, 11 deletions

diff --git a/target/arm/helper.c b/target/arm/helper.c
index b4618ee..85291d5 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -2608,6 +2608,39 @@ static uint64_t gt_get_countervalue(CPUARMState *env)
     return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / gt_cntfrq_period_ns(cpu);
 }
 
+static void gt_update_irq(ARMCPU *cpu, int timeridx)
+{
+    CPUARMState *env = &cpu->env;
+    uint64_t cnthctl = env->cp15.cnthctl_el2;
+    ARMSecuritySpace ss = arm_security_space(env);
+    /* ISTATUS && !IMASK */
+    int irqstate = (env->cp15.c14_timer[timeridx].ctl & 6) == 4;
+
+    /*
+     * If bit CNTHCTL_EL2.CNT[VP]MASK is set, it overrides IMASK.
+     * It is RES0 in Secure and NonSecure state.
+     */
+    if ((ss == ARMSS_Root || ss == ARMSS_Realm) &&
+        ((timeridx == GTIMER_VIRT && (cnthctl & CNTHCTL_CNTVMASK)) ||
+         (timeridx == GTIMER_PHYS && (cnthctl & CNTHCTL_CNTPMASK)))) {
+        irqstate = 0;
+    }
+
+    qemu_set_irq(cpu->gt_timer_outputs[timeridx], irqstate);
+    trace_arm_gt_update_irq(timeridx, irqstate);
+}
+
+void gt_rme_post_el_change(ARMCPU *cpu, void *ignored)
+{
+    /*
+     * Changing security state between Root and Secure/NonSecure, which may
+     * happen when switching EL, can change the effective value of CNTHCTL_EL2
+     * mask bits. Update the IRQ state accordingly.
+     */
+    gt_update_irq(cpu, GTIMER_VIRT);
+    gt_update_irq(cpu, GTIMER_PHYS);
+}
+
 static void gt_recalc_timer(ARMCPU *cpu, int timeridx)
 {
     ARMGenericTimer *gt = &cpu->env.cp15.c14_timer[timeridx];
@@ -2623,13 +2656,9 @@ static void gt_recalc_timer(ARMCPU *cpu, int timeridx)
         /* Note that this must be unsigned 64 bit arithmetic: */
         int istatus = count - offset >= gt->cval;
         uint64_t nexttick;
-        int irqstate;
 
         gt->ctl = deposit32(gt->ctl, 2, 1, istatus);
 
-        irqstate = (istatus && !(gt->ctl & 2));
-        qemu_set_irq(cpu->gt_timer_outputs[timeridx], irqstate);
-
         if (istatus) {
             /* Next transition is when count rolls back over to zero */
             nexttick = UINT64_MAX;
@@ -2648,14 +2677,14 @@ static void gt_recalc_timer(ARMCPU *cpu, int timeridx)
         } else {
             timer_mod(cpu->gt_timer[timeridx], nexttick);
         }
-        trace_arm_gt_recalc(timeridx, irqstate, nexttick);
+        trace_arm_gt_recalc(timeridx, nexttick);
     } else {
         /* Timer disabled: ISTATUS and timer output always clear */
         gt->ctl &= ~4;
-        qemu_set_irq(cpu->gt_timer_outputs[timeridx], 0);
         timer_del(cpu->gt_timer[timeridx]);
         trace_arm_gt_recalc_disabled(timeridx);
     }
+    gt_update_irq(cpu, timeridx);
 }
 
 static void gt_timer_reset(CPUARMState *env, const ARMCPRegInfo *ri,
@@ -2759,10 +2788,8 @@ static void gt_ctl_write(CPUARMState *env, const ARMCPRegInfo *ri,
          * IMASK toggled: don't need to recalculate,
          * just set the interrupt line based on ISTATUS
          */
-        int irqstate = (oldval & 4) && !(value & 2);
-
-        trace_arm_gt_imask_toggle(timeridx, irqstate);
-        qemu_set_irq(cpu->gt_timer_outputs[timeridx], irqstate);
+        trace_arm_gt_imask_toggle(timeridx);
+        gt_update_irq(cpu, timeridx);
     }
 }
 
@@ -2888,6 +2915,21 @@ static void gt_virt_ctl_write(CPUARMState *env, const ARMCPRegInfo *ri,
     gt_ctl_write(env, ri, GTIMER_VIRT, value);
 }
 
+static void gt_cnthctl_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                             uint64_t value)
+{
+    ARMCPU *cpu = env_archcpu(env);
+    uint32_t oldval = env->cp15.cnthctl_el2;
+
+    raw_write(env, ri, value);
+
+    if ((oldval ^ value) & CNTHCTL_CNTVMASK) {
+        gt_update_irq(cpu, GTIMER_VIRT);
+    } else if ((oldval ^ value) & CNTHCTL_CNTPMASK) {
+        gt_update_irq(cpu, GTIMER_PHYS);
+    }
+}
+
 static void gt_cntvoff_write(CPUARMState *env, const ARMCPRegInfo *ri,
                               uint64_t value)
 {
@@ -6203,7 +6245,8 @@ static const ARMCPRegInfo el2_cp_reginfo[] = {
        * reset values as IMPDEF. We choose to reset to 3 to comply with
        * both ARMv7 and ARMv8.
        */
-      .access = PL2_RW, .resetvalue = 3,
+      .access = PL2_RW, .type = ARM_CP_IO, .resetvalue = 3,
+      .writefn = gt_cnthctl_write, .raw_writefn = raw_write,
       .fieldoffset = offsetof(CPUARMState, cp15.cnthctl_el2) },
     { .name = "CNTVOFF_EL2", .state = ARM_CP_STATE_AA64,
       .opc0 = 3, .opc1 = 4, .crn = 14, .crm = 0, .opc2 = 3,