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acpi: cpuhp: introduce 'Command data 2' field 

No functional change in practice, patch only aims to properly
document (in spec and code) intended usage of the reserved space.

The new field is to be used for 2 purposes:
  - detection of modern CPU hotplug interface using
    CPHP_GET_NEXT_CPU_WITH_EVENT_CMD command.
    procedure will be described in follow up patch:
      "acpi: cpuhp: spec: add typical usecases"
  - for returning upper 32 bits of architecture specific CPU ID,
    for new CPHP_GET_CPU_ID_CMD command added by follow up patch:
      "acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command"

Change is backward compatible with 4.2 and older machines, as field was
unconditionally reserved and always returned 0x0 if modern CPU hotplug
interface was enabled.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1575896942-331151-8-git-send-email-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Igor Mammedov 2019-12-09 14:09:00 +01:00 committed by Michael S. Tsirkin
parent 5b8e5363fa
commit e6d0c3ce68
3 changed files with 16 additions and 1 deletions
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5
docs/specs/acpi_cpu_hotplug.txt
View File

@ -44,7 +44,10 @@ keeps the current value.
read access:
offset:
[0x0-0x3] reserved
[0x0-0x3] Command data 2: (DWORD access)
if value last stored in 'Command field':
0: reads as 0x0
other values: reserved
[0x4] CPU device status fields: (1 byte access)
bits:
0: Device is enabled and may be used by guest

11
hw/acpi/cpu.c
View File

@ -12,6 +12,7 @@
#define ACPI_CPU_FLAGS_OFFSET_RW 4
#define ACPI_CPU_CMD_OFFSET_WR 5
#define ACPI_CPU_CMD_DATA_OFFSET_RW 8
#define ACPI_CPU_CMD_DATA2_OFFSET_R 0
enum {
CPHP_GET_NEXT_CPU_WITH_EVENT_CMD = 0,
@ -79,6 +80,16 @@ static uint64_t cpu_hotplug_rd(void *opaque, hwaddr addr, unsigned size)
}
trace_cpuhp_acpi_read_cmd_data(cpu_st->selector, val);
break;
case ACPI_CPU_CMD_DATA2_OFFSET_R:
switch (cpu_st->command) {
case CPHP_GET_NEXT_CPU_WITH_EVENT_CMD:
val = 0;
break;
default:
break;
}
trace_cpuhp_acpi_read_cmd_data2(cpu_st->selector, val);
break;
default:
break;
}

1
hw/acpi/trace-events
View File

@ -23,6 +23,7 @@ cpuhp_acpi_read_flags(uint32_t idx, uint8_t flags) "idx[0x%"PRIx32"] flags: 0x%"
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_read_cmd_data(uint32_t idx, uint32_t data) "idx[0x%"PRIx32"] data: 0x%"PRIx32
cpuhp_acpi_read_cmd_data2(uint32_t idx, uint32_t data) "idx[0x%"PRIx32"] data: 0x%"PRIx32
cpuhp_acpi_cpu_has_events(uint32_t idx, bool ins, bool rm) "idx[0x%"PRIx32"] inserting: %d, removing: %d"
cpuhp_acpi_clear_inserting_evt(uint32_t idx) "idx[0x%"PRIx32"]"
cpuhp_acpi_clear_remove_evt(uint32_t idx) "idx[0x%"PRIx32"]"