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pc: Add 'etc/boot-cpus' fw_cfg file for machine with more than 255 CPUs

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Currently firmware uses 1 byte at 0x5F offset in RTC CMOS
to get number of CPUs present at boot. However 1 byte is
not enough to handle more than 255 CPUs.  So add a new
fw_cfg file that would allow QEMU to tell it.
For compat reasons add file only for machine types that
support more than 255 CPUs.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
This commit is contained in:
Igor Mammedov 2016-10-20 16:58:42 +02:00 committed by Eduardo Habkost
parent 079019f2e3
commit 080ac219cc
2 changed files with 31 additions and 15 deletions
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44
hw/i386/pc.c
View File

@ -1085,17 +1085,6 @@ void pc_acpi_smi_interrupt(void *opaque, int irq, int level)
}
}
static int pc_present_cpus_count(PCMachineState *pcms)
{
int i, boot_cpus = 0;
for (i = 0; i < pcms->possible_cpus->len; i++) {
if (pcms->possible_cpus->cpus[i].cpu) {
boot_cpus++;
}
}
return boot_cpus;
}
static X86CPU *pc_new_cpu(const char *typename, int64_t apic_id,
Error **errp)
{
@ -1232,6 +1221,19 @@ static void pc_build_feature_control_file(PCMachineState *pcms)
fw_cfg_add_file(pcms->fw_cfg, "etc/msr_feature_control", val, sizeof(*val));
}
static void rtc_set_cpus_count(ISADevice *rtc, uint16_t cpus_count)
{
if (cpus_count > 0xff) {
/* If the number of CPUs can't be represented in 8 bits, the
* BIOS must use "etc/boot-cpus". Set RTC field to 0 just
* to make old BIOSes fail more predictably.
*/
rtc_set_memory(rtc, 0x5f, 0);
} else {
rtc_set_memory(rtc, 0x5f, cpus_count - 1);
}
}
static
void pc_machine_done(Notifier *notifier, void *data)
{
@ -1240,7 +1242,7 @@ void pc_machine_done(Notifier *notifier, void *data)
PCIBus *bus = pcms->bus;
/* set the number of CPUs */
rtc_set_memory(pcms->rtc, 0x5f, pc_present_cpus_count(pcms) - 1);
rtc_set_cpus_count(pcms->rtc, le16_to_cpu(pcms->boot_cpus_le));
if (bus) {
int extra_hosts = 0;
@ -1261,8 +1263,15 @@ void pc_machine_done(Notifier *notifier, void *data)
acpi_setup();
if (pcms->fw_cfg) {
MachineClass *mc = MACHINE_GET_CLASS(pcms);
pc_build_smbios(pcms->fw_cfg);
pc_build_feature_control_file(pcms);
if (mc->max_cpus > 255) {
fw_cfg_add_file(pcms->fw_cfg, "etc/boot-cpus", &pcms->boot_cpus_le,
sizeof(pcms->boot_cpus_le));
}
}
}
@ -1786,9 +1795,11 @@ static void pc_cpu_plug(HotplugHandler *hotplug_dev,
}
}
/* increment the number of CPUs */
pcms->boot_cpus_le = cpu_to_le16(le16_to_cpu(pcms->boot_cpus_le) + 1);
if (dev->hotplugged) {
/* increment the number of CPUs */
rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) + 1);
/* Update the number of CPUs in CMOS */
rtc_set_cpus_count(pcms->rtc, le16_to_cpu(pcms->boot_cpus_le));
}
found_cpu = pc_find_cpu_slot(pcms, CPU(dev), NULL);
@ -1842,7 +1853,10 @@ static void pc_cpu_unplug_cb(HotplugHandler *hotplug_dev,
found_cpu->cpu = NULL;
object_unparent(OBJECT(dev));
rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) - 1);
/* decrement the number of CPUs */
pcms->boot_cpus_le = cpu_to_le16(le16_to_cpu(pcms->boot_cpus_le) - 1);
/* Update the number of CPUs in CMOS */
rtc_set_cpus_count(pcms->rtc, le16_to_cpu(pcms->boot_cpus_le));
out:
error_propagate(errp, local_err);
}

2
include/hw/i386/pc.h
View File

@ -37,6 +37,7 @@
/**
* PCMachineState:
* @acpi_dev: link to ACPI PM device that performs ACPI hotplug handling
* @boot_cpus_le: number of present VCPUs, referenced by 'etc/boot-cpus' fw_cfg
*/
struct PCMachineState {
/*< private >*/
@ -69,6 +70,7 @@ struct PCMachineState {
bool apic_xrupt_override;
unsigned apic_id_limit;
CPUArchIdList *possible_cpus;
uint16_t boot_cpus_le;
/* NUMA information: */
uint64_t numa_nodes;