[PATCH RFC 08/22] arm/cpuhp: Enable ACPI support for vcpu hotplug

[Salil Mehta <salil.mehta@huawei.com>]

ACPI is required to interface QEMU with the guest. Roughly falls into below
cases,

1. Convey the possible vcpus config at the machine init time to the guest
   using various DSDT tables like MADT etc.
2. Convey vcpu hotplug events to guest(using GED)
3. Assist in evaluation of various ACPI methods(like _EVT, _STA, _OST, _EJ0,
   _MAT etc.)
4. Provides ACPI cpu hotplug state and 12 Byte memory mapped cpu hotplug
   control register interface to the OSPM/guest corresponding to each possible
   vcpu. The register interface consists of various R/W fields and their
   handling operations. These are called when ever register fields or memory
   regions are accessed(i.e. read or written) by OSPM when ever it evaluates
   various ACPI methods.

Note: lot of this framework code is inherited from the changes already done for
      x86 but still some minor changes are required to make it compatible with
      ARM64.)

This patch enables the ACPI support for virtual cpu hotplug in kconfig and
during initialization.

Co-developed-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
---
 hw/acpi/cpu.c                 | 6 +++++-
 hw/arm/Kconfig                | 1 +
 hw/arm/virt.c                 | 2 ++
 include/hw/acpi/cpu_hotplug.h | 2 ++
 include/hw/arm/virt.h         | 1 +
 5 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
index 3d6a500fb7..21fe0463b9 100644
--- a/hw/acpi/cpu.c
+++ b/hw/acpi/cpu.c
@@ -218,7 +218,11 @@ void cpu_hotplug_hw_init(MemoryRegion *as, Object *owner,
     state->dev_count = id_list->len;
     state->devs = g_new0(typeof(*state->devs), state->dev_count);
     for (i = 0; i < id_list->len; i++) {
-        state->devs[i].cpu =  CPU(id_list->cpus[i].cpu);
+        struct CPUState *cpu = CPU(id_list->cpus[i].cpu);
+        if (qemu_present_cpu(cpu))
+            state->devs[i].cpu = cpu;
+        else
+            state->devs[i].cpu = NULL;
         state->devs[i].arch_id = id_list->cpus[i].arch_id;
     }
     memory_region_init_io(&state->ctrl_reg, owner, &cpu_hotplug_ops, state,
diff --git a/hw/arm/Kconfig b/hw/arm/Kconfig
index 9afa6eee79..cb67fb806b 100644
--- a/hw/arm/Kconfig
+++ b/hw/arm/Kconfig
@@ -26,6 +26,7 @@ config ARM_VIRT
     select ACPI_MEMORY_HOTPLUG
     select ACPI_HW_REDUCED
     select ACPI_NVDIMM
+    select ACPI_CPU_HOTPLUG
 
 config CHEETAH
     bool
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 7f938f289b..fe37babe35 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -75,6 +75,7 @@
 #include "hw/mem/pc-dimm.h"
 #include "hw/mem/nvdimm.h"
 #include "hw/acpi/generic_event_device.h"
+#include "hw/acpi/cpu_hotplug.h"
 #include "hw/virtio/virtio-iommu.h"
 #include "hw/char/pl011.h"
 #include "qemu/guest-random.h"
@@ -151,6 +152,7 @@ static const MemMapEntry base_memmap[] = {
     [VIRT_PCDIMM_ACPI] =        { 0x09070000, MEMORY_HOTPLUG_IO_LEN },
     [VIRT_ACPI_GED] =           { 0x09080000, ACPI_GED_EVT_SEL_LEN },
     [VIRT_NVDIMM_ACPI] =        { 0x09090000, NVDIMM_ACPI_IO_LEN},
+    [VIRT_CPUHP_ACPI] =         { 0x090a0000, ACPI_CPU_HOTPLUG_REG_LEN},
     [VIRT_MMIO] =               { 0x0a000000, 0x00000200 },
     /* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size */
     [VIRT_PLATFORM_BUS] =       { 0x0c000000, 0x02000000 },
diff --git a/include/hw/acpi/cpu_hotplug.h b/include/hw/acpi/cpu_hotplug.h
index 3b932abbbb..48b291e45e 100644
--- a/include/hw/acpi/cpu_hotplug.h
+++ b/include/hw/acpi/cpu_hotplug.h
@@ -19,6 +19,8 @@
 #include "hw/hotplug.h"
 #include "hw/acpi/cpu.h"
 
+#define ACPI_CPU_HOTPLUG_REG_LEN 12
+
 typedef struct AcpiCpuHotplug {
     Object *device;
     MemoryRegion io;
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index 3ffbda6217..e0bd9df69d 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -80,6 +80,7 @@ enum {
     VIRT_PCDIMM_ACPI,
     VIRT_ACPI_GED,
     VIRT_NVDIMM_ACPI,
+    VIRT_CPUHP_ACPI,
     VIRT_LOWMEMMAP_LAST,
 };
 
-- 
2.17.1