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>

target/arm/cpu.c

@@ -2169,6 +2169,12 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
         set_feature(env, ARM_FEATURE_VBAR);
     }
 
+#ifndef CONFIG_USER_ONLY
+    if (tcg_enabled() && cpu_isar_feature(aa64_rme, cpu)) {
+        arm_register_el_change_hook(cpu, &gt_rme_post_el_change, 0);
+    }
+#endif
+
     register_cp_regs_for_features(cpu);
     arm_cpu_register_gdb_regs_for_features(cpu);
 

target/arm/cpu.h

@@ -1115,6 +1115,7 @@ struct ArchCPU {
 };
 
 unsigned int gt_cntfrq_period_ns(ARMCPU *cpu);
+void gt_rme_post_el_change(ARMCPU *cpu, void *opaque);
 
 void arm_cpu_post_init(Object *obj);
 
@@ -1743,6 +1744,9 @@ static inline void xpsr_write(CPUARMState *env, uint32_t val, uint32_t mask)
 #define HSTR_TTEE (1 << 16)
 #define HSTR_TJDBX (1 << 17)
 
+#define CNTHCTL_CNTVMASK      (1 << 18)
+#define CNTHCTL_CNTPMASK      (1 << 19)
+
 /* Return the current FPSCR value.  */
 uint32_t vfp_get_fpscr(CPUARMState *env);
 void vfp_set_fpscr(CPUARMState *env, uint32_t val);

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,

target/arm/trace-events

@@ -1,13 +1,14 @@
 # See docs/devel/tracing.rst for syntax documentation.
 
 # helper.c
-arm_gt_recalc(int timer, int irqstate, uint64_t nexttick) "gt recalc: timer %d irqstate %d next tick 0x%" PRIx64
-arm_gt_recalc_disabled(int timer) "gt recalc: timer %d irqstate 0 timer disabled"
+arm_gt_recalc(int timer, uint64_t nexttick) "gt recalc: timer %d next tick 0x%" PRIx64
+arm_gt_recalc_disabled(int timer) "gt recalc: timer %d timer disabled"
 arm_gt_cval_write(int timer, uint64_t value) "gt_cval_write: timer %d value 0x%" PRIx64
 arm_gt_tval_write(int timer, uint64_t value) "gt_tval_write: timer %d value 0x%" PRIx64
 arm_gt_ctl_write(int timer, uint64_t value) "gt_ctl_write: timer %d value 0x%" PRIx64
-arm_gt_imask_toggle(int timer, int irqstate) "gt_ctl_write: timer %d IMASK toggle, new irqstate %d"
+arm_gt_imask_toggle(int timer) "gt_ctl_write: timer %d IMASK toggle"
 arm_gt_cntvoff_write(uint64_t value) "gt_cntvoff_write: value 0x%" PRIx64
+arm_gt_update_irq(int timer, int irqstate) "gt_update_irq: timer %d irqstate %d"
 
 # kvm.c
 kvm_arm_fixup_msi_route(uint64_t iova, uint64_t gpa) "MSI iova = 0x%"PRIx64" is translated into 0x%"PRIx64