On Mon, 14 Oct 2024 20:22:04 +0100
Salil Mehta <salil.me...@huawei.com> wrote:
> Reflect the ACPI CPU hotplug `is_{present, enabled}` states in the `_STA.PRES`
> (presence) and `_STA.ENA` (enabled) bits when the guest kernel evaluates the
> ACPI `_STA` method during initialization, as well as when vCPUs are
> hot-plugged
> or hot-unplugged. The presence of unplugged vCPUs may need to be deliberately
> *simulated* at the ACPI level to maintain a *persistent* view of vCPUs for the
> guest kernel.
given questionable future of is_present/is_enabled fields,
it probably premature to review this part.
The only thing, I have to say here is repeating spec/doc
update patch describing how it should work should come 1st,
so that we could compare this impl. with it.
>
> Signed-off-by: Salil Mehta <salil.me...@huawei.com>
> ---
> hw/acpi/cpu.c | 26 ++++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> index 700aa855e9..23ea2b9c70 100644
> --- a/hw/acpi/cpu.c
> +++ b/hw/acpi/cpu.c
> @@ -63,10 +63,11 @@ static uint64_t cpu_hotplug_rd(void *opaque, hwaddr addr,
> unsigned size)
> cdev = &cpu_st->devs[cpu_st->selector];
> switch (addr) {
> case ACPI_CPU_FLAGS_OFFSET_RW: /* pack and return is_* fields */
> - val |= cdev->cpu ? 1 : 0;
> + val |= cdev->is_enabled ? 1 : 0;
> val |= cdev->is_inserting ? 2 : 0;
> val |= cdev->is_removing ? 4 : 0;
> val |= cdev->fw_remove ? 16 : 0;
> + val |= cdev->is_present ? 32 : 0;
> trace_cpuhp_acpi_read_flags(cpu_st->selector, val);
> break;
> case ACPI_CPU_CMD_DATA_OFFSET_RW:
> @@ -376,6 +377,7 @@ const VMStateDescription vmstate_cpu_hotplug = {
> #define CPU_REMOVE_EVENT "CRMV"
> #define CPU_EJECT_EVENT "CEJ0"
> #define CPU_FW_EJECT_EVENT "CEJF"
> +#define CPU_PRESENT "CPRS"
>
> void build_cpus_aml(Aml *table, MachineState *machine, CPUHotplugFeatures
> opts,
> build_madt_cpu_fn build_madt_cpu, hwaddr base_addr,
> @@ -436,7 +438,9 @@ void build_cpus_aml(Aml *table, MachineState *machine,
> CPUHotplugFeatures opts,
> aml_append(field, aml_named_field(CPU_EJECT_EVENT, 1));
> /* tell firmware to do device eject, write only */
> aml_append(field, aml_named_field(CPU_FW_EJECT_EVENT, 1));
> - aml_append(field, aml_reserved_field(3));
> + /* 1 if present, read only */
> + aml_append(field, aml_named_field(CPU_PRESENT, 1));
> + aml_append(field, aml_reserved_field(2));
> aml_append(field, aml_named_field(CPU_COMMAND, 8));
> aml_append(cpu_ctrl_dev, field);
>
> @@ -466,6 +470,7 @@ void build_cpus_aml(Aml *table, MachineState *machine,
> CPUHotplugFeatures opts,
> Aml *ctrl_lock = aml_name("%s.%s", cphp_res_path, CPU_LOCK);
> Aml *cpu_selector = aml_name("%s.%s", cphp_res_path, CPU_SELECTOR);
> Aml *is_enabled = aml_name("%s.%s", cphp_res_path, CPU_ENABLED);
> + Aml *is_present = aml_name("%s.%s", cphp_res_path, CPU_PRESENT);
> Aml *cpu_cmd = aml_name("%s.%s", cphp_res_path, CPU_COMMAND);
> Aml *cpu_data = aml_name("%s.%s", cphp_res_path, CPU_DATA);
> Aml *ins_evt = aml_name("%s.%s", cphp_res_path, CPU_INSERT_EVENT);
> @@ -494,13 +499,26 @@ void build_cpus_aml(Aml *table, MachineState *machine,
> CPUHotplugFeatures opts,
> {
> Aml *idx = aml_arg(0);
> Aml *sta = aml_local(0);
> + Aml *ifctx2;
> + Aml *else_ctx;
>
> aml_append(method, aml_acquire(ctrl_lock, 0xFFFF));
> aml_append(method, aml_store(idx, cpu_selector));
> aml_append(method, aml_store(zero, sta));
> - ifctx = aml_if(aml_equal(is_enabled, one));
> + ifctx = aml_if(aml_equal(is_present, one));
> {
> - aml_append(ifctx, aml_store(aml_int(0xF), sta));
> + ifctx2 = aml_if(aml_equal(is_enabled, one));
> + {
> + /* cpu is present and enabled */
> + aml_append(ifctx2, aml_store(aml_int(0xF), sta));
> + }
> + aml_append(ifctx, ifctx2);
> + else_ctx = aml_else();
> + {
> + /* cpu is present but disabled */
> + aml_append(else_ctx, aml_store(aml_int(0xD), sta));
> + }
> + aml_append(ifctx, else_ctx);
> }
> aml_append(method, ifctx);
> aml_append(method, aml_release(ctrl_lock));
