[Qemu-devel] [RFC 34/42] acpi: cpuhp: add command and data registers

[Igor Mammedov <imammedo@redhat.com>]

CPU device has a lot of optional methods that might be
needed to be added in future in QEMU, so instead of
reserving/consuming IO/MMIO register for each of it
introduce a generic DATA read-write register which is
multiplexed by additional COMMAND write-only register.

currently that registers will be used for getting
CPU's _PXM value and setting _OST.event/_OST.status
values that OSPM reports to QEMU.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 hw/acpi/cpu.c         | 26 ++++++++++++++++++++++++++
 include/hw/acpi/cpu.h |  1 +
 trace-events          |  1 +
 3 files changed, 28 insertions(+)

diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
index f61d5a8..a238ced 100644
--- a/hw/acpi/cpu.c
+++ b/hw/acpi/cpu.c
@@ -7,6 +7,12 @@
 #define ACPI_CPU_HOTPLUG_REG_LEN 12
 #define ACPI_CPU_SELECTOR_OFFSET_WR 0
 #define ACPI_CPU_FLAGS_OFFSET_RW 4
+#define ACPI_CPU_CMD_OFFSET_WR 5
+#define ACPI_CPU_CMD_DATA_OFFSET_RW 8
+
+enum {
+    CPHP_CMD_MAX
+};
 
 static uint64_t cpu_hotplug_rd(void *opaque, hwaddr addr, unsigned size)
 {
@@ -27,6 +33,12 @@ static uint64_t cpu_hotplug_rd(void *opaque, hwaddr addr, unsigned size)
         val |= cdev->is_removing  ? 4 : 0;
         trace_cpuhp_acpi_read_flags(cpu_st->selector, val);
         break;
+    case ACPI_CPU_CMD_DATA_OFFSET_RW:
+        switch (cpu_st->command) {
+        default:
+           break;
+        }
+        break;
     default:
         break;
     }
@@ -80,6 +92,12 @@ static void cpu_hotplug_wr(void *opaque, hwaddr addr, uint64_t data,
             }
         }
         break;
+    case ACPI_CPU_CMD_OFFSET_WR:
+        trace_cpuhp_acpi_write_cmd(cpu_st->selector, data);
+        if (data < CPHP_CMD_MAX) {
+            cpu_st->command = data;
+        }
+        break;
     default:
         break;
     }
@@ -211,6 +229,7 @@ const VMStateDescription vmstate_cpu_hotplug = {
     .minimum_version_id_old = 1,
     .fields      = (VMStateField[]) {
         VMSTATE_UINT32(selector, CPUHotplugState),
+        VMSTATE_UINT32(command, CPUHotplugState),
         VMSTATE_STRUCT_VARRAY_POINTER_UINT32(devs, CPUHotplugState, dev_count,
                                              vmstate_cpuhp_sts, AcpiCpuStatus),
         VMSTATE_END_OF_LIST()
@@ -230,6 +249,8 @@ const VMStateDescription vmstate_cpu_hotplug = {
 #define CPU_EJECT_EVENT   "CEJ0"
 #define CPU_INSERT_EVENT  "CINS"
 #define CPU_REMOVE_EVENT  "CRMV"
+#define CPU_COMMAND       "CCMD"
+#define CPU_DATA          "CDAT"
 
 void build_cpus_aml(Aml *table, MachineState *machine, bool acpi1_compat,
                     const char *res_root, const char *event_handler_method,
@@ -281,11 +302,16 @@ void build_cpus_aml(Aml *table, MachineState *machine, bool acpi1_compat,
             aml_append(field, aml_named_field(CPU_REMOVE_EVENT, 1));
             /* initiates device eject, write only */
             aml_append(field, aml_named_field(CPU_EJECT_EVENT, 1));
+            aml_append(field, aml_reserved_field(4));
+            aml_append(field, aml_named_field(CPU_COMMAND, 8));
             aml_append(cpu_ctrl_dev, field);
 
             field = aml_field("PRST", AML_DWORD_ACC, AML_NOLOCK, AML_PRESERVE);
             /* CPU selector, write only */
             aml_append(field, aml_named_field(CPU_SELECTOR, 32));
+            /* flags + cmd + 2byte align */
+            aml_append(field, aml_reserved_field(4 * 8));
+            aml_append(field, aml_named_field(CPU_DATA, 32));
             aml_append(cpu_ctrl_dev, field);
 
         }
diff --git a/include/hw/acpi/cpu.h b/include/hw/acpi/cpu.h
index 829114f..6de9476 100644
--- a/include/hw/acpi/cpu.h
+++ b/include/hw/acpi/cpu.h
@@ -29,6 +29,7 @@ typedef struct CPUHotplugState {
     MemoryRegion ctrl_reg;
     bool is_enabled;
     uint32_t selector;
+    uint32_t command;
     uint32_t dev_count;
     AcpiCpuStatus *devs;
 } CPUHotplugState;
diff --git a/trace-events b/trace-events
index 9df9531..108ae07 100644
--- a/trace-events
+++ b/trace-events
@@ -1916,5 +1916,6 @@ cpuhp_acpi_read_flags(uint32_t idx, uint8_t flags) "idx[0x%"PRIx32"] flags: 0x%"
 cpuhp_acpi_clear_inserting_evt(uint32_t idx) "idx[0x%"PRIx32"]"
 cpuhp_acpi_clear_remove_evt(uint32_t idx) "idx[0x%"PRIx32"]"
 cpuhp_acpi_write_idx(uint32_t idx) "set active cpu idx: 0x%"PRIx32
+cpuhp_acpi_write_cmd(uint32_t idx, uint8_t cmd) "idx[0x%"PRIx32"] cmd: 0x%"PRIx8
 cpuhp_acpi_ejecting_invalid_cpu(uint32_t idx) "0x%"PRIx32
 cpuhp_acpi_ejecting_cpu(uint32_t idx) "0x%"PRIx32
-- 
1.8.3.1