[RFC PATCH v3 6/9] hw/arm/virt-acpi-build: Use possible cpus in generation of MADT

[Yanan Wang <wangyanan55@huawei.com>]

When building ACPI tables regarding CPUs we should always build
them for the number of possible CPUs, not the number of present
CPUs. So we create gicc nodes in MADT for possible cpus and then
ensure only the present CPUs are marked ENABLED. Furthermore, it
also needed if we are going to support CPU hotplug in the future.

Co-developed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Co-developed-by: Ying Fang <fangying1@huawei.com>
Signed-off-by: Ying Fang <fangying1@huawei.com>
Co-developed-by: Yanan Wang <wangyanan55@huawei.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 hw/arm/virt-acpi-build.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index a2d8e87616..4d64aeb865 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -481,6 +481,9 @@ build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     const int *irqmap = vms->irqmap;
     AcpiMadtGenericDistributor *gicd;
     AcpiMadtGenericMsiFrame *gic_msi;
+    MachineClass *mc = MACHINE_GET_CLASS(vms);
+    const CPUArchIdList *possible_cpus = mc->possible_cpu_arch_ids(MACHINE(vms));
+    bool pmu;
     int i;
 
     acpi_data_push(table_data, sizeof(AcpiMultipleApicTable));
@@ -491,11 +494,21 @@ build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     gicd->base_address = cpu_to_le64(memmap[VIRT_GIC_DIST].base);
     gicd->version = vms->gic_version;
 
-    for (i = 0; i < MACHINE(vms)->smp.cpus; i++) {
+    for (i = 0; i < possible_cpus->len; i++) {
         AcpiMadtGenericCpuInterface *gicc = acpi_data_push(table_data,
                                                            sizeof(*gicc));
         ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(i));
 
+        /*
+         * PMU should have been either implemented for all CPUs or not,
+         * so we only get information from the first CPU, which could
+         * represent the others.
+         */
+        if (i == 0) {
+            pmu = arm_feature(&armcpu->env, ARM_FEATURE_PMU);
+        }
+        assert(!armcpu || arm_feature(&armcpu->env, ARM_FEATURE_PMU) == pmu);
+
         gicc->type = ACPI_APIC_GENERIC_CPU_INTERFACE;
         gicc->length = sizeof(*gicc);
         if (vms->gic_version == 2) {
@@ -504,11 +517,19 @@ build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
             gicc->gicv_base_address = cpu_to_le64(memmap[VIRT_GIC_VCPU].base);
         }
         gicc->cpu_interface_number = cpu_to_le32(i);
-        gicc->arm_mpidr = cpu_to_le64(armcpu->mp_affinity);
+        gicc->arm_mpidr = cpu_to_le64(possible_cpus->cpus[i].arch_id);
         gicc->uid = cpu_to_le32(i);
-        gicc->flags = cpu_to_le32(ACPI_MADT_GICC_ENABLED);
 
-        if (arm_feature(&armcpu->env, ARM_FEATURE_PMU)) {
+        /*
+         * ACPI spec says that LAPIC entry for non present CPU may be
+         * omitted from MADT or it must be marked as disabled. Here we
+         * choose to also keep the disabled ones in MADT.
+         */
+        if (possible_cpus->cpus[i].cpu != NULL) {
+            gicc->flags = cpu_to_le32(ACPI_MADT_GICC_ENABLED);
+        }
+
+        if (pmu) {
             gicc->performance_interrupt = cpu_to_le32(PPI(VIRTUAL_PMU_IRQ));
         }
         if (vms->virt) {
-- 
2.19.1