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Re: [Qemu-devel] [PATCH v3 04/19] pc: cpu: consolidate apic-id validity
From: |
Bandan Das |
Subject: |
Re: [Qemu-devel] [PATCH v3 04/19] pc: cpu: consolidate apic-id validity checks in pc_cpu_pre_plug() |
Date: |
Wed, 13 Jul 2016 18:16:59 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Igor Mammedov <address@hidden> writes:
> Machine code knows about all possible APIC IDs so use that
> instead of hack which does O(n^2) complexity duplicate
> checks, interating over global CPUs list.
> As result duplicate check is done only once with O(log n) complexity.
>
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
> hw/i386/pc.c | 44 ++++++++++++++++++++++++++++++++------------
> target-i386/cpu.c | 13 -------------
> 2 files changed, 32 insertions(+), 25 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 3c42d84..99dfbe0 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1071,18 +1071,6 @@ void pc_hot_add_cpu(const int64_t id, Error **errp)
> return;
> }
>
> - if (cpu_exists(apic_id)) {
> - error_setg(errp, "Unable to add CPU: %" PRIi64
> - ", it already exists", id);
> - return;
> - }
> -
> - if (id >= max_cpus) {
> - error_setg(errp, "Unable to add CPU: %" PRIi64
> - ", max allowed: %d", id, max_cpus - 1);
> - return;
> - }
> -
> if (apic_id >= ACPI_CPU_HOTPLUG_ID_LIMIT) {
> error_setg(errp, "Unable to add CPU: %" PRIi64
> ", resulting APIC ID (%" PRIi64 ") is too large",
> @@ -1771,6 +1759,37 @@ static void pc_cpu_unplug_cb(HotplugHandler
> *hotplug_dev,
> error_propagate(errp, local_err);
> }
>
> +static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
> + DeviceState *dev, Error **errp)
> +{
> + int idx;
> + X86CPU *cpu = X86_CPU(dev);
> + PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> + CPUArchId *cpu_slot = pc_find_cpu_slot(pcms, CPU(dev), &idx);
> +
> + if (!cpu_slot) {
> + error_setg(errp, "Invalid CPU index with APIC ID (%" PRIu32
> + "), valid range 0:%d", cpu->apic_id,
> + pcms->possible_cpus->len - 1);
> + return;
> + }
> +
> + if (cpu_slot->cpu) {
> + error_setg(errp, "CPU[%ld] with APIC ID %" PRIu32 " exists",
> + cpu_slot - pcms->possible_cpus->cpus,
> + cpu->apic_id);
> + return;
> + }
> +}
> +
> +static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
> + DeviceState *dev, Error **errp)
> +{
> + if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
> + pc_cpu_pre_plug(hotplug_dev, dev, errp);
> + }
> +}
>
Will this path be invoked for non TYPE_CPU callbacks too ? I was just wondering
if there should be an "else" error message.
Bandan
> static void pc_machine_device_plug_cb(HotplugHandler *hotplug_dev,
> DeviceState *dev, Error **errp)
> {
> @@ -2068,6 +2087,7 @@ static void pc_machine_class_init(ObjectClass *oc, void
> *data)
> mc->hot_add_cpu = pc_hot_add_cpu;
> mc->max_cpus = 255;
> mc->reset = pc_machine_reset;
> + hc->pre_plug = pc_machine_device_pre_plug_cb;
> hc->plug = pc_machine_device_plug_cb;
> hc->unplug_request = pc_machine_device_unplug_request_cb;
> hc->unplug = pc_machine_device_unplug_cb;
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index e7319e3..9511474 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1838,8 +1838,6 @@ static void x86_cpuid_set_apic_id(Object *obj, Visitor
> *v, const char *name,
> {
> X86CPU *cpu = X86_CPU(obj);
> DeviceState *dev = DEVICE(obj);
> - const int64_t min = 0;
> - const int64_t max = UINT32_MAX;
> Error *error = NULL;
> int64_t value;
>
> @@ -1854,17 +1852,6 @@ static void x86_cpuid_set_apic_id(Object *obj, Visitor
> *v, const char *name,
> error_propagate(errp, error);
> return;
> }
> - if (value < min || value > max) {
> - error_setg(errp, "Property %s.%s doesn't take value %" PRId64
> - " (minimum: %" PRId64 ", maximum: %" PRId64 ")" ,
> - object_get_typename(obj), name, value, min, max);
> - return;
> - }
> -
> - if ((value != cpu->apic_id) && cpu_exists(value)) {
> - error_setg(errp, "CPU with APIC ID %" PRIi64 " exists", value);
> - return;
> - }
> cpu->apic_id = value;
> }