Commit 080ac219 authored by Igor Mammedov's avatar Igor Mammedov Committed by Eduardo Habkost
Browse files

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



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: default avatarIgor Mammedov <imammedo@redhat.com>
Reviewed-by: default avatarEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: default avatarEduardo Habkost <ehabkost@redhat.com>
parent 079019f2

hw/i386/pc.c

+29 −15
Original line number Diff line number Diff line
@@ -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, 
        }

    }



    if (dev->hotplugged) {

    /* increment the number of CPUs */

        rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) + 1);

    pcms->boot_cpus_le = cpu_to_le16(le16_to_cpu(pcms->boot_cpus_le) + 1);

    if (dev->hotplugged) {

        /* 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);

}

include/hw/i386/pc.h

+2 −0
Original line number Diff line number Diff line
@@ -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;