[PATCH RFC 18/22] arm/cpuhp: Changes to update GIC with vcpu hot-plug notification

[Salil Mehta]

Adds the notification support about vcpu hot-(un)plug required to update the
GIC so that it can update its vcpu to GIC cpu interface association.

NOTE: This is using 'struct VirtMachineState' inside the notifier function.
      Question:  Not sure if it is right to use machine related data structure
      inside GIC related files? Its design looks to be pretty much abstracted
      from any machine related stuff. @Peter Maydell

Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
 hw/arm/virt.c                      | 12 +++++--
 hw/intc/arm_gicv3_common.c         | 54 ++++++++++++++++++++++++++++++
 hw/intc/arm_gicv3_cpuif.c          |  5 +++
 hw/intc/gicv3_internal.h           |  1 +
 include/hw/arm/virt.h              |  1 +
 include/hw/intc/arm_gicv3_common.h |  1 +
 6 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index f0295e940e..b4cfd53a59 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1928,6 +1928,8 @@ static void machvirt_init(MachineState *machine)
 
     create_fdt(vms);
 
+    notifier_list_init(&vms->cpuhp_notifiers);
+
     possible_cpus = mc->possible_cpu_arch_ids(machine);
     for (n = 0; n < possible_cpus->len; n++) {
         Object *cpuobj;
@@ -2378,6 +2380,12 @@ out:
     error_propagate(errp, local_err);
 }
 
+static void virt_update_gic(VirtMachineState *vms, CPUState *cs)
+{
+    /* notify gic to stitch GICC to this new cpu */
+    notifier_list_notify(&vms->cpuhp_notifiers, cs);
+}
+
 static void virt_cpu_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
                               Error **errp)
 {
@@ -2432,7 +2440,7 @@ static void virt_cpu_pre_plug(HotplugHandler 
*hotplug_dev, DeviceState *dev,
     virt_cpu_set_properties(OBJECT(cs), cpu_slot);
 
     if (dev->hotplugged) {
-        /* TODO: update GIC about this hotplug change here */
+        virt_update_gic(vms, cs);
     }
 }
 
@@ -2506,7 +2514,7 @@ static void virt_cpu_unplug(HotplugHandler *hotplug_dev, 
DeviceState *dev,
     /* TODO: update the acpi cpu hotplug state for cpu hot-unplug */
 
     unwire_gic_cpu_irqs(vms, cs);
-    /* TODO: update the GIC about this hot unplug change */
+    virt_update_gic(vms, cs);
 
     /* TODO: unregister this cpu for reset & update F/W info for the next boot 
*/
 
diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
index bfa514444a..f6b7b359cb 100644
--- a/hw/intc/arm_gicv3_common.c
+++ b/hw/intc/arm_gicv3_common.c
@@ -31,6 +31,7 @@
 #include "gicv3_internal.h"
 #include "hw/arm/linux-boot-if.h"
 #include "sysemu/kvm.h"
+#include "hw/arm/virt.h"
 
 
 static void gicv3_gicd_no_migration_shift_bug_post_load(GICv3State *cs)
@@ -305,8 +306,57 @@ void gicv3_init_irqs_and_mmio(GICv3State *s, 
qemu_irq_handler handler,
     }
 }
 
+static int arm_gicv3_get_proc_num(GICv3State *s, CPUState *cpu)
+{
+    uint64_t mp_affinity;
+    uint64_t gicr_typer;
+    uint64_t cpu_affid;
+    int i;
+
+    mp_affinity = object_property_get_uint(OBJECT(cpu), "mp-affinity", NULL);
+    /* match the cpu mp-affinity to get the gic cpuif number */
+    for (i = 0; i < s->num_cpu; i++) {
+        gicr_typer = s->cpu[i].gicr_typer;
+        cpu_affid = (gicr_typer >> 32) & 0xFFFFFF;
+        if (cpu_affid == mp_affinity) {
+            return i;
+        }
+    }
+
+    return -1;
+}
+
+static void arm_gicv3_cpu_update_notifier(Notifier * notifier, void * data)
+{
+    VirtMachineState *vms = VIRT_MACHINE(qdev_get_machine());
+    GICv3State *s = ARM_GICV3_COMMON(vms->gic);
+    CPUState *cpu = (CPUState *)data;
+    int gic_cpuif_num;
+
+    /* this shall get us mapped gicv3 cpuif corresponding to mpidr */
+    gic_cpuif_num = arm_gicv3_get_proc_num(s, cpu);
+    if (gic_cpuif_num < 0) {
+        error_report("Failed to associate cpu %d with any GIC cpuif",
+                     cpu->cpu_index);
+        abort();
+    }
+
+    /* check if update is for vcpu hot-unplug */
+    if (qemu_present_cpu(cpu)) {
+        s->cpu[gic_cpuif_num].cpu = NULL;
+        return;
+    }
+
+    /* re-stitch the gic cpuif to this new cpu */
+    gicv3_set_gicv3state(cpu, &s->cpu[gic_cpuif_num]);
+    gicv3_set_cpustate(&s->cpu[gic_cpuif_num], cpu);
+
+    /* TODO: initialize the registers info for this newly added cpu */
+}
+
 static void arm_gicv3_common_realize(DeviceState *dev, Error **errp)
 {
+    VirtMachineState *vms = VIRT_MACHINE(qdev_get_machine());
     GICv3State *s = ARM_GICV3_COMMON(dev);
     int i;
 
@@ -386,12 +436,16 @@ static void arm_gicv3_common_realize(DeviceState *dev, 
Error **errp)
             (i << 8) |
             (last << 4);
     }
+
+    s->cpu_update_notifier.notify = arm_gicv3_cpu_update_notifier;
+    notifier_list_add(&vms->cpuhp_notifiers, &s->cpu_update_notifier);
 }
 
 static void arm_gicv3_finalize(Object *obj)
 {
     GICv3State *s = ARM_GICV3_COMMON(obj);
 
+    notifier_remove(&s->cpu_update_notifier);
     g_free(s->redist_region_count);
 }
 
diff --git a/hw/intc/arm_gicv3_cpuif.c b/hw/intc/arm_gicv3_cpuif.c
index 90d8b0118e..b3aa5979ca 100644
--- a/hw/intc/arm_gicv3_cpuif.c
+++ b/hw/intc/arm_gicv3_cpuif.c
@@ -20,6 +20,11 @@
 #include "hw/irq.h"
 #include "cpu.h"
 
+void gicv3_set_cpustate(GICv3CPUState *s, CPUState *cpu)
+{
+    s->cpu = cpu;
+}
+
 void gicv3_set_gicv3state(CPUState *cpu, GICv3CPUState *s)
 {
     ARMCPU *arm_cpu = ARM_CPU(cpu);
diff --git a/hw/intc/gicv3_internal.h b/hw/intc/gicv3_internal.h
index 05303a55c8..6e14a7a6cd 100644
--- a/hw/intc/gicv3_internal.h
+++ b/hw/intc/gicv3_internal.h
@@ -409,5 +409,6 @@ static inline void 
gicv3_cache_all_target_cpustates(GICv3State *s)
 }
 
 void gicv3_set_gicv3state(CPUState *cpu, GICv3CPUState *s);
+void gicv3_set_cpustate(GICv3CPUState *s, CPUState *cpu);
 
 #endif /* QEMU_ARM_GICV3_INTERNAL_H */
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index e8468d8cf6..c287433219 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -158,6 +158,7 @@ typedef struct {
     DeviceState *gic;
     DeviceState *acpi_dev;
     Notifier powerdown_notifier;
+    NotifierList cpuhp_notifiers;
 } VirtMachineState;
 
 #define VIRT_ECAM_ID(high) (high ? VIRT_HIGH_PCIE_ECAM : VIRT_PCIE_ECAM)
diff --git a/include/hw/intc/arm_gicv3_common.h 
b/include/hw/intc/arm_gicv3_common.h
index 31ec9a1ae4..b51f74c728 100644
--- a/include/hw/intc/arm_gicv3_common.h
+++ b/include/hw/intc/arm_gicv3_common.h
@@ -248,6 +248,7 @@ struct GICv3State {
     GICv3CPUState *gicd_irouter_target[GICV3_MAXIRQ];
     uint32_t gicd_nsacr[DIV_ROUND_UP(GICV3_MAXIRQ, 16)];
 
+    Notifier cpu_update_notifier;
     GICv3CPUState *cpu;
 };
 
-- 
2.17.1