From e676038e606eb3daddd5bd18f7896921e3bc1e7d Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Wed, 14 Feb 2018 20:40:53 +0100 Subject: [PATCH] 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 [dwg: Rename spapr_is_vcore() to spapr_is_thread0_in_vcore() for clarity] Signed-off-by: David Gibson (cherry picked from commit 5d0fb1508e2d279da74ef4a103e8def9b52c6304) Signed-off-by: Greg Kurz --- hw/ppc/spapr.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-) diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c index 0be60fb044..a36494b87b 100644 --- a/hw/ppc/spapr.c +++ b/hw/ppc/spapr.c @@ -100,6 +100,21 @@ #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) @@ -346,7 +361,7 @@ 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; } @@ -2230,7 +2245,7 @@ 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) { @@ -3274,7 +3289,8 @@ 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); @@ -3303,7 +3319,8 @@ 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); @@ -3652,8 +3669,7 @@ 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); -- 2.39.5