[PATCH RFC V2 21/37] hw/arm: MADT Tbl change to size the guest with possible vCPUs

[Salil Mehta]

Changes required during building of MADT Table by QEMU to accomodate disabled
possible vCPUs. This info shall be used by the guest kernel to size up its
resources during boot time. This pre-sizing of the guest kernel done on
possible vCPUs will facilitate hotplug of the disabled vCPUs.

This change also caters ACPI MADT GIC CPU Interface flag related changes
recently introduced in the UEFI ACPI 6.5 Specification which allows deferred
virtual CPU online'ing in the Guest Kernel.

Link: 
https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#gic-cpu-interface-gicc-structure

Co-developed-by: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
 hw/arm/virt-acpi-build.c | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index d27df5030e..cbccd2ca2d 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -700,6 +700,29 @@ static void build_append_gicr(GArray *table_data, uint64_t 
base, uint32_t size)
     build_append_int_noprefix(table_data, size, 4); /* Discovery Range Length 
*/
 }
 
+static uint32_t virt_acpi_get_gicc_flags(CPUState *cpu)
+{
+    MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
+
+    /* can only exist in 'enabled' state */
+    if (!mc->has_hotpluggable_cpus) {
+        return 1;
+    }
+
+    /*
+     * ARM GIC CPU Interface can be 'online-capable' or 'enabled' at boot
+     * We MUST set 'online-capable' Bit for all hotpluggable CPUs except the
+     * first/boot CPU. Cold-booted CPUs without 'Id' can also be unplugged.
+     * Though as-of-now this is only used as a debugging feature.
+     *
+     *   UEFI ACPI Specification 6.5
+     *   Section: 5.2.12.14. GIC CPU Interface (GICC) Structure
+     *   Table:   5.37 GICC CPU Interface Flags
+     *   Link: https://uefi.org/specs/ACPI/6.5
+     */
+    return cpu && !cpu->cpu_index ? 1 : (1 << 3);
+}
+
 static void
 build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
 {
@@ -726,12 +749,13 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
VirtMachineState *vms)
     build_append_int_noprefix(table_data, vms->gic_version, 1);
     build_append_int_noprefix(table_data, 0, 3);   /* Reserved */
 
-    for (i = 0; i < MACHINE(vms)->smp.cpus; i++) {
-        ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(i));
+    for (i = 0; i < MACHINE(vms)->smp.max_cpus; i++) {
+        CPUState *cpu = qemu_get_possible_cpu(i);
         uint64_t physical_base_address = 0, gich = 0, gicv = 0;
         uint32_t vgic_interrupt = vms->virt ? PPI(ARCH_GIC_MAINT_IRQ) : 0;
-        uint32_t pmu_interrupt = arm_feature(&armcpu->env, ARM_FEATURE_PMU) ?
-                                             PPI(VIRTUAL_PMU_IRQ) : 0;
+        uint32_t pmu_interrupt = vms->pmu ? PPI(VIRTUAL_PMU_IRQ) : 0;
+        uint32_t flags = virt_acpi_get_gicc_flags(cpu);
+        uint64_t mpidr = qemu_get_cpu_archid(i);
 
         if (vms->gic_version == VIRT_GIC_VERSION_2) {
             physical_base_address = memmap[VIRT_GIC_CPU].base;
@@ -746,7 +770,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
VirtMachineState *vms)
         build_append_int_noprefix(table_data, i, 4);    /* GIC ID */
         build_append_int_noprefix(table_data, i, 4);    /* ACPI Processor UID 
*/
         /* Flags */
-        build_append_int_noprefix(table_data, 1, 4);    /* Enabled */
+        build_append_int_noprefix(table_data, flags, 4);
         /* Parking Protocol Version */
         build_append_int_noprefix(table_data, 0, 4);
         /* Performance Interrupt GSIV */
@@ -760,7 +784,7 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
VirtMachineState *vms)
         build_append_int_noprefix(table_data, vgic_interrupt, 4);
         build_append_int_noprefix(table_data, 0, 8);    /* GICR Base Address*/
         /* MPIDR */
-        build_append_int_noprefix(table_data, armcpu->mp_affinity, 8);
+        build_append_int_noprefix(table_data, mpidr, 8);
         /* Processor Power Efficiency Class */
         build_append_int_noprefix(table_data, 0, 1);
         /* Reserved */
-- 
2.34.1