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spapr: consolidate the VCPU id numbering logic in a single place 

Several places in the code need to calculate a VCPU id:

    (cpu_index / smp_threads) * spapr->vsmt + cpu_index % smp_threads
    (core_id / smp_threads) * spapr->vsmt (1 user)
    index * spapr->vsmt (2 users)

or guess that the VCPU id of a given VCPU is the first thread of a virtual
core:

    index % spapr->vsmt != 0

Even if the numbering logic isn't that complex, it is rather fragile to
have these assumptions open-coded in several places. FWIW this was
proved with recent issues related to VSMT.

This patch moves the VCPU id formula to a single function to be called
everywhere the code needs to compute one. It also adds an helper to
guess if a VCPU is the first thread of a VCORE.

Signed-off-by: Greg Kurz <groug@kaod.org>
[dwg: Rename spapr_is_vcore() to spapr_is_thread0_in_vcore() for clarity]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Greg Kurz 2018-02-14 20:40:53 +01:00 committed by David Gibson
parent 14bb4486c8
commit 5d0fb1508e
1 changed files with 23 additions and 7 deletions
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30
hw/ppc/spapr.c
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@ -99,6 +99,21 @@
#define PHANDLE_XICP 0x00001111
/* These two functions implement the VCPU id numbering: one to compute them
* all and one to identify thread 0 of a VCORE. Any change to the first one
* is likely to have an impact on the second one, so let's keep them close.
*/
static int spapr_vcpu_id(sPAPRMachineState *spapr, int cpu_index)
{
return
(cpu_index / smp_threads) * spapr->vsmt + cpu_index % smp_threads;
}
static bool spapr_is_thread0_in_vcore(sPAPRMachineState *spapr,
PowerPCCPU *cpu)
{
return spapr_get_vcpu_id(cpu) % spapr->vsmt == 0;
}
static ICSState *spapr_ics_create(sPAPRMachineState *spapr,
const char *type_ics,
int nr_irqs, Error **errp)
@ -345,7 +360,7 @@ static int spapr_fixup_cpu_dt(void *fdt, sPAPRMachineState *spapr)
int index = spapr_get_vcpu_id(cpu);
int compat_smt = MIN(smp_threads, ppc_compat_max_vthreads(cpu));
if (index % spapr->vsmt != 0) {
if (!spapr_is_thread0_in_vcore(spapr, cpu)) {
continue;
}
@ -630,7 +645,7 @@ static void spapr_populate_cpus_dt_node(void *fdt, sPAPRMachineState *spapr)
DeviceClass *dc = DEVICE_GET_CLASS(cs);
int offset;
if (index % spapr->vsmt != 0) {
if (!spapr_is_thread0_in_vcore(spapr, cpu)) {
continue;
}
@ -2251,7 +2266,7 @@ static void spapr_init_cpus(sPAPRMachineState *spapr)
if (mc->has_hotpluggable_cpus) {
spapr_dr_connector_new(OBJECT(spapr), TYPE_SPAPR_DRC_CPU,
(core_id / smp_threads) * spapr->vsmt);
spapr_vcpu_id(spapr, core_id));
}
if (i < boot_cores_nr) {
@ -3293,7 +3308,8 @@ void spapr_core_unplug_request(HotplugHandler *hotplug_dev, DeviceState *dev,
return;
}
drc = spapr_drc_by_id(TYPE_SPAPR_DRC_CPU, index * spapr->vsmt);
drc = spapr_drc_by_id(TYPE_SPAPR_DRC_CPU,
spapr_vcpu_id(spapr, cc->core_id));
g_assert(drc);
spapr_drc_detach(drc);
@ -3322,7 +3338,8 @@ static void spapr_core_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
cc->core_id);
return;
}
drc = spapr_drc_by_id(TYPE_SPAPR_DRC_CPU, index * spapr->vsmt);
drc = spapr_drc_by_id(TYPE_SPAPR_DRC_CPU,
spapr_vcpu_id(spapr, cc->core_id));
g_assert(drc || !mc->has_hotpluggable_cpus);
@ -3807,8 +3824,7 @@ void spapr_set_vcpu_id(PowerPCCPU *cpu, int cpu_index, Error **errp)
sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
int vcpu_id;
vcpu_id =
(cpu_index / smp_threads) * spapr->vsmt + cpu_index % smp_threads;
vcpu_id = spapr_vcpu_id(spapr, cpu_index);
if (kvm_enabled() && !kvm_vcpu_id_is_valid(vcpu_id)) {
error_setg(errp, "Can't create CPU with id %d in KVM", vcpu_id);