| Message ID | 20240526122612.473476-7-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 5/26/24 17:56, Nicholas Piggin wrote: > The way SMT thread siblings are matched is clunky, using hard-coded > logic that checks the PIR SPR. > > Change that to use a new core_index variable in the CPUPPCState, > where all siblings have the same core_index. CPU realize routines have > flexibility in setting core/sibling topology. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > target/ppc/cpu.h | 5 ++++- > hw/ppc/pnv_core.c | 2 ++ > hw/ppc/spapr_cpu_core.c | 3 +++ > 3 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h > index dac13d4dac..9a89083932 100644 > --- a/target/ppc/cpu.h > +++ b/target/ppc/cpu.h > @@ -1247,6 +1247,9 @@ struct CPUArchState { > /* when a memory exception occurs, the access type is stored here */ > int access_type; > > + /* For SMT processors */ > + int core_index; > + > #if !defined(CONFIG_USER_ONLY) > /* MMU context, only relevant for full system emulation */ > #if defined(TARGET_PPC64) > @@ -1404,7 +1407,7 @@ struct CPUArchState { > }; > > #define _CORE_ID(cs) \ > - (POWERPC_CPU(cs)->env.spr_cb[SPR_PIR].default_value & ~(cs->nr_threads - 1)) > + (POWERPC_CPU(cs)->env.core_index) Dont we want to keep the logical & with ~(cs->nr_threads - 1) ? How's it taken care ? > > #define THREAD_SIBLING_FOREACH(cs, cs_sibling) \ > CPU_FOREACH(cs_sibling) \ > diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c > index 9b5edd9e48..0f61aabb77 100644 > --- a/hw/ppc/pnv_core.c > +++ b/hw/ppc/pnv_core.c > @@ -252,6 +252,8 @@ 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; > + > /* Set time-base frequency to 512 MHz */ > cpu_ppc_tb_init(env, PNV_TIMEBASE_FREQ); > } > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c > index e7c9edd033..059d372c8a 100644 > --- a/hw/ppc/spapr_cpu_core.c > +++ b/hw/ppc/spapr_cpu_core.c > @@ -300,16 +300,19 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp) > g_autofree char *id = NULL; > CPUState *cs; > PowerPCCPU *cpu; > + CPUPPCState *env; > > obj = object_new(scc->cpu_type); > > cs = CPU(obj); > cpu = POWERPC_CPU(obj); > + env = &cpu->env; > /* > * All CPUs start halted. CPU0 is unhalted from the machine level reset code > * and the rest are explicitly started up by the guest using an RTAS call. > */ > qdev_prop_set_bit(DEVICE(obj), "start-powered-off", true); > + env->core_index = cc->core_id; We could just do cpu->env.core_index and avoid creating local var env. regards, Harsh > cs->cpu_index = cc->core_id + i; > if (!spapr_set_vcpu_id(cpu, cs->cpu_index, errp)) { > return NULL;
corrected typo, it's bitwise. On 5/28/24 14:18, Harsh Prateek Bora wrote: >> - (POWERPC_CPU(cs)->env.spr_cb[SPR_PIR].default_value & >> ~(cs->nr_threads - 1)) >> + (POWERPC_CPU(cs)->env.core_index) > > Dont we want to keep the bitwise & with ~(cs->nr_threads - 1) ? > How's it taken care ?
On Tue May 28, 2024 at 6:52 PM AEST, Harsh Prateek Bora wrote: > corrected typo, it's bitwise. > > On 5/28/24 14:18, Harsh Prateek Bora wrote: > >> - (POWERPC_CPU(cs)->env.spr_cb[SPR_PIR].default_value & > >> ~(cs->nr_threads - 1)) > >> + (POWERPC_CPU(cs)->env.core_index) > > > > Dont we want to keep the bitwise & with ~(cs->nr_threads - 1) ? > > How's it taken care ? For these accessors it actually just wants to have something that compares if a CPU belongs to the same core or not, so exact value doesn't really matter. Maybe the helpers should do that comparison. It could possibly even be a class method to be really clean, although that's more costly to call (but writing to a SMT shared register is pretty costly anyway so maybe doesn't matter). I'll think a bit more. Thanks, Nick
diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h index dac13d4dac..9a89083932 100644 --- a/target/ppc/cpu.h +++ b/target/ppc/cpu.h @@ -1247,6 +1247,9 @@ struct CPUArchState { /* when a memory exception occurs, the access type is stored here */ int access_type; + /* For SMT processors */ + int core_index; + #if !defined(CONFIG_USER_ONLY) /* MMU context, only relevant for full system emulation */ #if defined(TARGET_PPC64) @@ -1404,7 +1407,7 @@ struct CPUArchState { }; #define _CORE_ID(cs) \ - (POWERPC_CPU(cs)->env.spr_cb[SPR_PIR].default_value & ~(cs->nr_threads - 1)) + (POWERPC_CPU(cs)->env.core_index) #define THREAD_SIBLING_FOREACH(cs, cs_sibling) \ CPU_FOREACH(cs_sibling) \ diff --git a/hw/ppc/pnv_core.c b/hw/ppc/pnv_core.c index 9b5edd9e48..0f61aabb77 100644 --- a/hw/ppc/pnv_core.c +++ b/hw/ppc/pnv_core.c @@ -252,6 +252,8 @@ 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; + /* Set time-base frequency to 512 MHz */ cpu_ppc_tb_init(env, PNV_TIMEBASE_FREQ); } diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c index e7c9edd033..059d372c8a 100644 --- a/hw/ppc/spapr_cpu_core.c +++ b/hw/ppc/spapr_cpu_core.c @@ -300,16 +300,19 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *sc, int i, Error **errp) g_autofree char *id = NULL; CPUState *cs; PowerPCCPU *cpu; + CPUPPCState *env; obj = object_new(scc->cpu_type); cs = CPU(obj); cpu = POWERPC_CPU(obj); + env = &cpu->env; /* * All CPUs start halted. CPU0 is unhalted from the machine level reset code * and the rest are explicitly started up by the guest using an RTAS call. */ qdev_prop_set_bit(DEVICE(obj), "start-powered-off", true); + env->core_index = cc->core_id; cs->cpu_index = cc->core_id + i; if (!spapr_set_vcpu_id(cpu, cs->cpu_index, errp)) { return NULL;
The way SMT thread siblings are matched is clunky, using hard-coded logic that checks the PIR SPR. Change that to use a new core_index variable in the CPUPPCState, where all siblings have the same core_index. CPU realize routines have flexibility in setting core/sibling topology. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- target/ppc/cpu.h | 5 ++++- hw/ppc/pnv_core.c | 2 ++ hw/ppc/spapr_cpu_core.c | 3 +++ 3 files changed, 9 insertions(+), 1 deletion(-)