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acpi: cpuhp: introduce 'Command data 2' field

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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"]"