| Message ID | 20240712120247.477133-11-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ppc/pnv: Better big-core model, lpar-per-core, PC unit | expand |
On 7/12/24 14:02, Nicholas Piggin wrote: > POWER9 and POWER10 machines come in two variants, big-core and > small-core. Big-core machines are SMT8 from software's point of view, > but the low level platform topology ("xscom registers and pervasive > addressing"), these look more like a pair of small cores ganged > together. > > Presently the way this is modelled is to create one SMT8 PnvCore and add > special cases to xscom and pervasive for big-core mode that tries to > split this into two small cores, but this is becoming too complicated to > manage. > > A better approach is to create 2 core structures and ganging them > together to look like an SMT8 core in TCG. Then the xscom and pervasive > models mostly do not need to differentiate big and small core modes. > > This change adds initial mode bits and QEMU topology handling to > split SMT8 cores into 2xSMT4 cores. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Looks good. See some proposal below, > --- > include/hw/ppc/pnv.h | 2 + > include/hw/ppc/pnv_chip.h | 1 + > include/hw/ppc/pnv_core.h | 1 + > hw/ppc/pnv.c | 77 ++++++++++++++++++++++++++++++++------- > hw/ppc/pnv_core.c | 7 +++- > 5 files changed, 74 insertions(+), 14 deletions(-) > > diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h > index 1993dededf..283ddd50e7 100644 > --- a/include/hw/ppc/pnv.h > +++ b/include/hw/ppc/pnv.h > @@ -101,6 +101,8 @@ struct PnvMachineState { > PnvPnor *pnor; > > hwaddr fw_load_addr; > + > + bool big_core; > }; > > PnvChip *pnv_get_chip(PnvMachineState *pnv, uint32_t chip_id); > diff --git a/include/hw/ppc/pnv_chip.h b/include/hw/ppc/pnv_chip.h > index 7d5d08bcdc..69d8273efe 100644 > --- a/include/hw/ppc/pnv_chip.h > +++ b/include/hw/ppc/pnv_chip.h > @@ -27,6 +27,7 @@ struct PnvChip { > uint64_t ram_start; > uint64_t ram_size; > > + bool big_core; > uint32_t nr_cores; > uint32_t nr_threads; > uint64_t cores_mask; > diff --git a/include/hw/ppc/pnv_core.h b/include/hw/ppc/pnv_core.h > index 693acb189b..50164e9e1f 100644 > --- a/include/hw/ppc/pnv_core.h > +++ b/include/hw/ppc/pnv_core.h > @@ -49,6 +49,7 @@ struct PnvCore { > > /*< public >*/ > PowerPCCPU **threads; > + bool big_core; > uint32_t pir; > uint32_t hwid; > uint64_t hrmor; > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c > index eee34ca926..555a983536 100644 > --- a/hw/ppc/pnv.c > +++ b/hw/ppc/pnv.c > @@ -1002,14 +1002,39 @@ static void pnv_init(MachineState *machine) > pnv->num_chips = > machine->smp.max_cpus / (machine->smp.cores * machine->smp.threads); > > + if (pnv->big_core) { > + if (machine->smp.threads % 2 == 1) { > + error_report("Cannot support %d threads with big-core option " > + "because it must be an even number", > + machine->smp.threads); > + exit(1); > + } > + max_smt_threads *= 2; > + } > + > if (machine->smp.threads > max_smt_threads) { > error_report("Cannot support more than %d threads/core " > "on %s machine", max_smt_threads, mc->desc); > + if (pmc->max_smt_threads == 4) { > + error_report("(use big-core=on for 8 threads per core)"); > + } > exit(1); > } > > + if (pnv->big_core) { > + /* > + * powernv models PnvCore as a SMT4 core. Big-core requires 2xPnvCore > + * per core, so adjust topology here. pnv_dt_core() processor > + * device-tree and TCG SMT code make the 2 cores appear as one big core > + * from software point of view. pnv pervasive models and xscoms tend to > + * see the big core as 2 small core halves. > + */ > + machine->smp.cores *= 2; > + machine->smp.threads /= 2; > + } > + > if (!is_power_of_2(machine->smp.threads)) { > - error_report("Cannot support %d threads/core on a powernv" > + error_report("Cannot support %d threads/core on a powernv " > "machine because it must be a power of 2", > machine->smp.threads); > exit(1); please add : @@ -1054,6 +1079,9 @@ static void pnv_init(MachineState *machi &error_fatal); object_property_set_int(chip, "nr-threads", machine->smp.threads, &error_fatal); + object_property_set_bool(chip, "big-core", pnv->big_core, + &error_fatal); + /* * The POWER8 machine use the XICS interrupt interface. * Propagate the XICS fabric to the chip and its controllers. > @@ -1175,11 +1200,17 @@ static void pnv_get_pir_tir_p9(PnvChip *chip, > uint32_t core_id, uint32_t thread_id, > uint32_t *pir, uint32_t *tir) > { > - if (pir) { > - if (chip->nr_threads == 8) { > - *pir = (chip->chip_id << 8) | ((thread_id & 1) << 2) | > - (core_id << 3) | (thread_id >> 1); > - } else { > + if (chip->big_core) { > + /* Big-core interleaves thread ID between small-cores */ > + thread_id <<= 1; > + thread_id |= core_id & 1; > + core_id >>= 1; > + > + if (pir) { > + *pir = (chip->chip_id << 8) | (core_id << 3) | thread_id; > + } > + } else { > + if (pir) { > *pir = (chip->chip_id << 8) | (core_id << 2) | thread_id; > } > } > @@ -1203,11 +1234,17 @@ static void pnv_get_pir_tir_p10(PnvChip *chip, > uint32_t core_id, uint32_t thread_id, > uint32_t *pir, uint32_t *tir) > { > - if (pir) { > - if (chip->nr_threads == 8) { > - *pir = (chip->chip_id << 8) | ((core_id / 4) << 4) | > - ((core_id % 2) << 3) | thread_id; > - } else { > + if (chip->big_core) { > + /* Big-core interleaves thread ID between small-cores */ > + thread_id <<= 1; > + thread_id |= core_id & 1; > + core_id >>= 1; > + > + if (pir) { > + *pir = (chip->chip_id << 8) | (core_id << 3) | thread_id; > + } > + } else { > + if (pir) { > *pir = (chip->chip_id << 8) | (core_id << 2) | thread_id; > } > } > @@ -2180,7 +2217,8 @@ static void pnv_chip_power10_class_init(ObjectClass *klass, void *data) > &k->parent_realize); > } > > -static void pnv_chip_core_sanitize(PnvChip *chip, Error **errp) > +static void pnv_chip_core_sanitize(PnvMachineState *pnv, PnvChip *chip, > + Error **errp) > { > PnvChipClass *pcc = PNV_CHIP_GET_CLASS(chip); > int cores_max; > @@ -2201,6 +2239,17 @@ static void pnv_chip_core_sanitize(PnvChip *chip, Error **errp) > } > chip->cores_mask &= pcc->cores_mask; > > + /* Ensure small-cores a paired up in big-core mode */ > + if (pnv->big_core) { > + uint64_t even_cores = chip->cores_mask & 0x5555555555555555ULL; > + uint64_t odd_cores = chip->cores_mask & 0xaaaaaaaaaaaaaaaaULL; > + > + if (even_cores ^ (odd_cores >> 1)) { > + error_setg(errp, "warning: unpaired cores in big-core mode !"); > + return; > + } > + } > + > /* now that we have a sane layout, let check the number of cores */ > cores_max = ctpop64(chip->cores_mask); > if (chip->nr_cores > cores_max) { > @@ -2224,12 +2273,14 @@ static void pnv_chip_core_realize(PnvChip *chip, Error **errp) > } > > /* Cores */ > - pnv_chip_core_sanitize(chip, &error); > + pnv_chip_core_sanitize(pnv, chip, &error); > if (error) { > error_propagate(errp, error); > return; > } > > + chip->big_core = pnv->big_core; > + drop that and instead : @@ -2282,6 +2334,8 @@ static void pnv_chip_core_realize(PnvChi &error_fatal); object_property_set_link(OBJECT(pnv_core), "chip", OBJECT(chip), &error_abort); + object_property_set_bool(OBJECT(pnv_core), "big-core", chip->big_core, + &error_abort); qdev_realize(DEVICE(pnv_core), NULL, &error_fatal); /* Each core has an XSCOM MMIO region */ @@ -2313,6 +2367,7 @@ static Property pnv_chip_properties[] = DEFINE_PROP_UINT32("nr-cores", PnvChip, nr_cores, 1), DEFINE_PROP_UINT64("cores-mask", PnvChip, cores_mask, 0x0), DEFINE_PROP_UINT32("nr-threads", PnvChip, nr_threads, 1), + DEFINE_PROP_BOOL("big-core", PnvChip, big_core, false), DEFINE_PROP_END_OF_LIST(), }; > chip->cores = g_new0(PnvCore *, chip->nr_cores); > > for (i = 0, core_hwid = 0; (core_hwid < sizeof(chip->cores_mask) * 8) > diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c > index 8cfa94fbfa..16d40392db 100644 > --- a/hw/ppc/pnv_core.c > +++ b/hw/ppc/pnv_core.c > @@ -249,7 +249,12 @@ static void pnv_core_cpu_realize(PnvCore *pc, PowerPCCPU *cpu, Error **errp, > pir_spr->default_value = pir; > tir_spr->default_value = tir; > > - env->core_index = core_hwid; > + if (pc->big_core) { > + /* 2 "small cores" get the same core index for SMT operations */ > + env->core_index = core_hwid >> 1; > + } else { > + env->core_index = core_hwid; > + } > > /* Set time-base frequency to 512 MHz */ > cpu_ppc_tb_init(env, PNV_TIMEBASE_FREQ); please add : @@ -355,6 +360,7 @@ static Property pnv_core_properties[] = DEFINE_PROP_UINT32("hwid", PnvCore, hwid, 0), DEFINE_PROP_UINT64("hrmor", PnvCore, hrmor, 0), DEFINE_PROP_LINK("chip", PnvCore, chip, TYPE_PNV_CHIP, PnvChip *), + DEFINE_PROP_BOOL("big-core", PnvCore, big_core, false), DEFINE_PROP_END_OF_LIST(), }; Thanks, C.
On Sat Jul 13, 2024 at 5:19 PM AEST, Cédric Le Goater wrote: > On 7/12/24 14:02, Nicholas Piggin wrote: > > POWER9 and POWER10 machines come in two variants, big-core and > > small-core. Big-core machines are SMT8 from software's point of view, > > but the low level platform topology ("xscom registers and pervasive > > addressing"), these look more like a pair of small cores ganged > > together. > > > > Presently the way this is modelled is to create one SMT8 PnvCore and add > > special cases to xscom and pervasive for big-core mode that tries to > > split this into two small cores, but this is becoming too complicated to > > manage. > > > > A better approach is to create 2 core structures and ganging them > > together to look like an SMT8 core in TCG. Then the xscom and pervasive > > models mostly do not need to differentiate big and small core modes. > > > > This change adds initial mode bits and QEMU topology handling to > > split SMT8 cores into 2xSMT4 cores. > > > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > > Looks good. See some proposal below, [snip] All make sense, thank you will do. Thnaks, Nick
diff --git a/include/hw/ppc/pnv.h b/include/hw/ppc/pnv.h index 1993dededf..283ddd50e7 100644 --- a/include/hw/ppc/pnv.h +++ b/include/hw/ppc/pnv.h @@ -101,6 +101,8 @@ struct PnvMachineState { PnvPnor *pnor; hwaddr fw_load_addr; + + bool big_core; }; PnvChip *pnv_get_chip(PnvMachineState *pnv, uint32_t chip_id); diff --git a/include/hw/ppc/pnv_chip.h b/include/hw/ppc/pnv_chip.h index 7d5d08bcdc..69d8273efe 100644 --- a/include/hw/ppc/pnv_chip.h +++ b/include/hw/ppc/pnv_chip.h @@ -27,6 +27,7 @@ struct PnvChip { uint64_t ram_start; uint64_t ram_size; + bool big_core; uint32_t nr_cores; uint32_t nr_threads; uint64_t cores_mask; diff --git a/include/hw/ppc/pnv_core.h b/include/hw/ppc/pnv_core.h index 693acb189b..50164e9e1f 100644 --- a/include/hw/ppc/pnv_core.h +++ b/include/hw/ppc/pnv_core.h @@ -49,6 +49,7 @@ struct PnvCore { /*< public >*/ PowerPCCPU **threads; + bool big_core; uint32_t pir; uint32_t hwid; uint64_t hrmor; diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c index eee34ca926..555a983536 100644 --- a/hw/ppc/pnv.c +++ b/hw/ppc/pnv.c @@ -1002,14 +1002,39 @@ static void pnv_init(MachineState *machine) pnv->num_chips = machine->smp.max_cpus / (machine->smp.cores * machine->smp.threads); + if (pnv->big_core) { + if (machine->smp.threads % 2 == 1) { + error_report("Cannot support %d threads with big-core option " + "because it must be an even number", + machine->smp.threads); + exit(1); + } + max_smt_threads *= 2; + } + if (machine->smp.threads > max_smt_threads) { error_report("Cannot support more than %d threads/core " "on %s machine", max_smt_threads, mc->desc); + if (pmc->max_smt_threads == 4) { + error_report("(use big-core=on for 8 threads per core)"); + } exit(1); } + if (pnv->big_core) { + /* + * powernv models PnvCore as a SMT4 core. Big-core requires 2xPnvCore + * per core, so adjust topology here. pnv_dt_core() processor + * device-tree and TCG SMT code make the 2 cores appear as one big core + * from software point of view. pnv pervasive models and xscoms tend to + * see the big core as 2 small core halves. + */ + machine->smp.cores *= 2; + machine->smp.threads /= 2; + } + if (!is_power_of_2(machine->smp.threads)) { - error_report("Cannot support %d threads/core on a powernv" + error_report("Cannot support %d threads/core on a powernv " "machine because it must be a power of 2", machine->smp.threads); exit(1); @@ -1175,11 +1200,17 @@ static void pnv_get_pir_tir_p9(PnvChip *chip, uint32_t core_id, uint32_t thread_id, uint32_t *pir, uint32_t *tir) { - if (pir) { - if (chip->nr_threads == 8) { - *pir = (chip->chip_id << 8) | ((thread_id & 1) << 2) | - (core_id << 3) | (thread_id >> 1); - } else { + if (chip->big_core) { + /* Big-core interleaves thread ID between small-cores */ + thread_id <<= 1; + thread_id |= core_id & 1; + core_id >>= 1; + + if (pir) { + *pir = (chip->chip_id << 8) | (core_id << 3) | thread_id; + } + } else { + if (pir) { *pir = (chip->chip_id << 8) | (core_id << 2) | thread_id; } } @@ -1203,11 +1234,17 @@ static void pnv_get_pir_tir_p10(PnvChip *chip, uint32_t core_id, uint32_t thread_id, uint32_t *pir, uint32_t *tir) { - if (pir) { - if (chip->nr_threads == 8) { - *pir = (chip->chip_id << 8) | ((core_id / 4) << 4) | - ((core_id % 2) << 3) | thread_id; - } else { + if (chip->big_core) { + /* Big-core interleaves thread ID between small-cores */ + thread_id <<= 1; + thread_id |= core_id & 1; + core_id >>= 1; + + if (pir) { + *pir = (chip->chip_id << 8) | (core_id << 3) | thread_id; + } + } else { + if (pir) { *pir = (chip->chip_id << 8) | (core_id << 2) | thread_id; } } @@ -2180,7 +2217,8 @@ static void pnv_chip_power10_class_init(ObjectClass *klass, void *data) &k->parent_realize); } -static void pnv_chip_core_sanitize(PnvChip *chip, Error **errp) +static void pnv_chip_core_sanitize(PnvMachineState *pnv, PnvChip *chip, + Error **errp) { PnvChipClass *pcc = PNV_CHIP_GET_CLASS(chip); int cores_max; @@ -2201,6 +2239,17 @@ static void pnv_chip_core_sanitize(PnvChip *chip, Error **errp) } chip->cores_mask &= pcc->cores_mask; + /* Ensure small-cores a paired up in big-core mode */ + if (pnv->big_core) { + uint64_t even_cores = chip->cores_mask & 0x5555555555555555ULL; + uint64_t odd_cores = chip->cores_mask & 0xaaaaaaaaaaaaaaaaULL; + + if (even_cores ^ (odd_cores >> 1)) { + error_setg(errp, "warning: unpaired cores in big-core mode !"); + return; + } + } + /* now that we have a sane layout, let check the number of cores */ cores_max = ctpop64(chip->cores_mask); if (chip->nr_cores > cores_max) { @@ -2224,12 +2273,14 @@ static void pnv_chip_core_realize(PnvChip *chip, Error **errp) } /* Cores */ - pnv_chip_core_sanitize(chip, &error); + pnv_chip_core_sanitize(pnv, chip, &error); if (error) { error_propagate(errp, error); return; } + chip->big_core = pnv->big_core; + chip->cores = g_new0(PnvCore *, chip->nr_cores); for (i = 0, core_hwid = 0; (core_hwid < sizeof(chip->cores_mask) * 8) diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c index 8cfa94fbfa..16d40392db 100644 --- a/hw/ppc/pnv_core.c +++ b/hw/ppc/pnv_core.c @@ -249,7 +249,12 @@ static void pnv_core_cpu_realize(PnvCore *pc, PowerPCCPU *cpu, Error **errp, pir_spr->default_value = pir; tir_spr->default_value = tir; - env->core_index = core_hwid; + if (pc->big_core) { + /* 2 "small cores" get the same core index for SMT operations */ + env->core_index = core_hwid >> 1; + } else { + env->core_index = core_hwid; + } /* Set time-base frequency to 512 MHz */ cpu_ppc_tb_init(env, PNV_TIMEBASE_FREQ);
POWER9 and POWER10 machines come in two variants, big-core and small-core. Big-core machines are SMT8 from software's point of view, but the low level platform topology ("xscom registers and pervasive addressing"), these look more like a pair of small cores ganged together. Presently the way this is modelled is to create one SMT8 PnvCore and add special cases to xscom and pervasive for big-core mode that tries to split this into two small cores, but this is becoming too complicated to manage. A better approach is to create 2 core structures and ganging them together to look like an SMT8 core in TCG. Then the xscom and pervasive models mostly do not need to differentiate big and small core modes. This change adds initial mode bits and QEMU topology handling to split SMT8 cores into 2xSMT4 cores. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- include/hw/ppc/pnv.h | 2 + include/hw/ppc/pnv_chip.h | 1 + include/hw/ppc/pnv_core.h | 1 + hw/ppc/pnv.c | 77 ++++++++++++++++++++++++++++++++------- hw/ppc/pnv_core.c | 7 +++- 5 files changed, 74 insertions(+), 14 deletions(-)