| Message ID | 20240506145605.73794-1-gautam@linux.ibm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v6] arch/powerpc/kvm: Add support for reading VPA counters for pseries guests | expand |
On Mon, May 06, 2024 at 08:26:03PM GMT, Gautam Menghani wrote: > PAPR hypervisor has introduced three new counters in the VPA area of > LPAR CPUs for KVM L2 guest (see [1] for terminology) observability - 2 > for context switches from host to guest and vice versa, and 1 counter > for getting the total time spent inside the KVM guest. Add a tracepoint > that enables reading the counters for use by ftrace/perf. Note that this > tracepoint is only available for nestedv2 API (i.e, KVM on PowerVM). > > [1] Terminology: > a. L1 refers to the VM (LPAR) booted on top of PAPR hypervisor > b. L2 refers to the KVM guest booted on top of L1. > > Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> > Signed-off-by: Gautam Menghani <gautam@linux.ibm.com> > --- > v5 -> v6: > 1. Use TRACE_EVENT_FN to enable/disable counters only once. > 2. Remove the agg. counters from vcpu->arch. > 3. Use PACA to maintain old counter values instead of zeroing on every > entry. > 4. Simplify variable names > > v4 -> v5: > 1. Define helper functions for getting/setting the accumulation counter > in L2's VPA > > v3 -> v4: > 1. After vcpu_run, check the VPA flag instead of checking for tracepoint > being enabled for disabling the cs time accumulation. > > v2 -> v3: > 1. Move the counter disabling and zeroing code to a different function. > 2. Move the get_lppaca() inside the tracepoint_enabled() branch. > 3. Add the aggregation logic to maintain total context switch time. > > v1 -> v2: > 1. Fix the build error due to invalid struct member reference. > > arch/powerpc/include/asm/lppaca.h | 11 +++++-- > arch/powerpc/include/asm/paca.h | 5 +++ > arch/powerpc/kvm/book3s_hv.c | 52 +++++++++++++++++++++++++++++++ > arch/powerpc/kvm/trace_hv.h | 27 ++++++++++++++++ > 4 files changed, 92 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h > index 61ec2447dabf..f40a646bee3c 100644 > --- a/arch/powerpc/include/asm/lppaca.h > +++ b/arch/powerpc/include/asm/lppaca.h > @@ -62,7 +62,8 @@ struct lppaca { > u8 donate_dedicated_cpu; /* Donate dedicated CPU cycles */ > u8 fpregs_in_use; > u8 pmcregs_in_use; > - u8 reserved8[28]; > + u8 l2_counters_enable; /* Enable usage of counters for KVM guest */ > + u8 reserved8[27]; > __be64 wait_state_cycles; /* Wait cycles for this proc */ > u8 reserved9[28]; > __be16 slb_count; /* # of SLBs to maintain */ > @@ -92,9 +93,13 @@ struct lppaca { > /* cacheline 4-5 */ > > __be32 page_ins; /* CMO Hint - # page ins by OS */ > - u8 reserved12[148]; > + u8 reserved12[28]; > + volatile __be64 l1_to_l2_cs_tb; > + volatile __be64 l2_to_l1_cs_tb; > + volatile __be64 l2_runtime_tb; > + u8 reserved13[96]; > volatile __be64 dtl_idx; /* Dispatch Trace Log head index */ > - u8 reserved13[96]; > + u8 reserved14[96]; > } ____cacheline_aligned; > > #define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr) > diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h > index 1d58da946739..f20ac7a6efa4 100644 > --- a/arch/powerpc/include/asm/paca.h > +++ b/arch/powerpc/include/asm/paca.h > @@ -278,6 +278,11 @@ struct paca_struct { > struct mce_info *mce_info; > u8 mce_pending_irq_work; > #endif /* CONFIG_PPC_BOOK3S_64 */ > +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > + u64 l1_to_l2_cs; > + u64 l2_to_l1_cs; > + u64 l2_runtime_agg; > +#endif > } ____cacheline_aligned; > > extern void copy_mm_to_paca(struct mm_struct *mm); > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 8e86eb577eb8..ed69ad58bd02 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -4108,6 +4108,54 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu) > } > } > > +static inline int kvmhv_get_l2_counters_status(void) > +{ > + return get_lppaca()->l2_counters_enable; > +} > + > +static inline void kvmhv_set_l2_counters_status(int cpu, bool status) > +{ > + if (status) > + lppaca_of(cpu).l2_counters_enable = 1; > + else > + lppaca_of(cpu).l2_counters_enable = 0; > +} > + > +int kmvhv_counters_tracepoint_regfunc(void) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) { > + kvmhv_set_l2_counters_status(cpu, true); > + } > + return 0; > +} > + > +void kmvhv_counters_tracepoint_unregfunc(void) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) { > + kvmhv_set_l2_counters_status(cpu, false); > + } > +} > + > +static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu) > +{ > + struct lppaca *lp = get_lppaca(); > + u64 l1_to_l2_ns, l2_to_l1_ns, l2_runtime_ns; > + > + l1_to_l2_ns = tb_to_ns(be64_to_cpu(lp->l1_to_l2_cs_tb)); > + l2_to_l1_ns = tb_to_ns(be64_to_cpu(lp->l2_to_l1_cs_tb)); > + l2_runtime_ns = tb_to_ns(be64_to_cpu(lp->l2_runtime_tb)); > + trace_kvmppc_vcpu_stats(vcpu, l1_to_l2_ns - local_paca->l1_to_l2_cs, > + l2_to_l1_ns - local_paca->l2_to_l1_cs, > + l2_runtime_ns - local_paca->l2_runtime_agg); Depending on how the hypervisor works, if the vcpu was in l2 when the tracepoint is enabled, the counters may not be updated on exit and we may emit a trace with all values zero. If that is possible, it might be a good idea to only emit the trace if any of the counters are non-zero. Otherwise, this looks good to me. Acked-by: Naveen N Rao <naveen@kernel.org> - Naveen > + local_paca->l1_to_l2_cs = l1_to_l2_ns; > + local_paca->l2_to_l1_cs = l2_to_l1_ns; > + local_paca->l2_runtime_agg = l2_runtime_ns; > +} > + > static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, > unsigned long lpcr, u64 *tb) > { > @@ -4156,6 +4204,10 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, > > timer_rearm_host_dec(*tb); > > + /* Record context switch and guest_run_time data */ > + if (kvmhv_get_l2_counters_status()) > + do_trace_nested_cs_time(vcpu); > + > return trap; > } > > diff --git a/arch/powerpc/kvm/trace_hv.h b/arch/powerpc/kvm/trace_hv.h > index 8d57c8428531..dc118ab88f23 100644 > --- a/arch/powerpc/kvm/trace_hv.h > +++ b/arch/powerpc/kvm/trace_hv.h > @@ -238,6 +238,9 @@ > {H_MULTI_THREADS_ACTIVE, "H_MULTI_THREADS_ACTIVE"}, \ > {H_OUTSTANDING_COP_OPS, "H_OUTSTANDING_COP_OPS"} > > +int kmvhv_counters_tracepoint_regfunc(void); > +void kmvhv_counters_tracepoint_unregfunc(void); > + > TRACE_EVENT(kvm_guest_enter, > TP_PROTO(struct kvm_vcpu *vcpu), > TP_ARGS(vcpu), > @@ -512,6 +515,30 @@ TRACE_EVENT(kvmppc_run_vcpu_exit, > __entry->vcpu_id, __entry->exit, __entry->ret) > ); > > +TRACE_EVENT_FN(kvmppc_vcpu_stats, > + TP_PROTO(struct kvm_vcpu *vcpu, u64 l1_to_l2_cs, u64 l2_to_l1_cs, u64 l2_runtime), > + > + TP_ARGS(vcpu, l1_to_l2_cs, l2_to_l1_cs, l2_runtime), > + > + TP_STRUCT__entry( > + __field(int, vcpu_id) > + __field(u64, l1_to_l2_cs) > + __field(u64, l2_to_l1_cs) > + __field(u64, l2_runtime) > + ), > + > + TP_fast_assign( > + __entry->vcpu_id = vcpu->vcpu_id; > + __entry->l1_to_l2_cs = l1_to_l2_cs; > + __entry->l2_to_l1_cs = l2_to_l1_cs; > + __entry->l2_runtime = l2_runtime; > + ), > + > + TP_printk("VCPU %d: l1_to_l2_cs_time=%llu ns l2_to_l1_cs_time=%llu ns l2_runtime=%llu ns", > + __entry->vcpu_id, __entry->l1_to_l2_cs, > + __entry->l2_to_l1_cs, __entry->l2_runtime), > + kmvhv_counters_tracepoint_regfunc, kmvhv_counters_tracepoint_unregfunc > +); > #endif /* _TRACE_KVM_HV_H */ > > /* This part must be outside protection */ > -- > 2.44.0 >
On Tue May 7, 2024 at 12:56 AM AEST, Gautam Menghani wrote: > PAPR hypervisor has introduced three new counters in the VPA area of > LPAR CPUs for KVM L2 guest (see [1] for terminology) observability - 2 > for context switches from host to guest and vice versa, and 1 counter > for getting the total time spent inside the KVM guest. Add a tracepoint > that enables reading the counters for use by ftrace/perf. Note that this > tracepoint is only available for nestedv2 API (i.e, KVM on PowerVM). > > [1] Terminology: > a. L1 refers to the VM (LPAR) booted on top of PAPR hypervisor > b. L2 refers to the KVM guest booted on top of L1. > > Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com> > Signed-off-by: Gautam Menghani <gautam@linux.ibm.com> > --- > v5 -> v6: > 1. Use TRACE_EVENT_FN to enable/disable counters only once. > 2. Remove the agg. counters from vcpu->arch. > 3. Use PACA to maintain old counter values instead of zeroing on every > entry. > 4. Simplify variable names > > v4 -> v5: > 1. Define helper functions for getting/setting the accumulation counter > in L2's VPA > > v3 -> v4: > 1. After vcpu_run, check the VPA flag instead of checking for tracepoint > being enabled for disabling the cs time accumulation. > > v2 -> v3: > 1. Move the counter disabling and zeroing code to a different function. > 2. Move the get_lppaca() inside the tracepoint_enabled() branch. > 3. Add the aggregation logic to maintain total context switch time. > > v1 -> v2: > 1. Fix the build error due to invalid struct member reference. > > arch/powerpc/include/asm/lppaca.h | 11 +++++-- > arch/powerpc/include/asm/paca.h | 5 +++ > arch/powerpc/kvm/book3s_hv.c | 52 +++++++++++++++++++++++++++++++ > arch/powerpc/kvm/trace_hv.h | 27 ++++++++++++++++ > 4 files changed, 92 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h > index 61ec2447dabf..f40a646bee3c 100644 > --- a/arch/powerpc/include/asm/lppaca.h > +++ b/arch/powerpc/include/asm/lppaca.h > @@ -62,7 +62,8 @@ struct lppaca { > u8 donate_dedicated_cpu; /* Donate dedicated CPU cycles */ > u8 fpregs_in_use; > u8 pmcregs_in_use; > - u8 reserved8[28]; > + u8 l2_counters_enable; /* Enable usage of counters for KVM guest */ > + u8 reserved8[27]; > __be64 wait_state_cycles; /* Wait cycles for this proc */ > u8 reserved9[28]; > __be16 slb_count; /* # of SLBs to maintain */ > @@ -92,9 +93,13 @@ struct lppaca { > /* cacheline 4-5 */ > > __be32 page_ins; /* CMO Hint - # page ins by OS */ > - u8 reserved12[148]; > + u8 reserved12[28]; > + volatile __be64 l1_to_l2_cs_tb; > + volatile __be64 l2_to_l1_cs_tb; > + volatile __be64 l2_runtime_tb; I wonder if we shouldn't be moving over to use READ_ONCE for these instead of volatile. Probably doesn't really matter here. Maybe general audit of volatiles in arch/powerpc could be something to put in linuxppc issues. > + u8 reserved13[96]; > volatile __be64 dtl_idx; /* Dispatch Trace Log head index */ > - u8 reserved13[96]; > + u8 reserved14[96]; > } ____cacheline_aligned; > > #define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr) > diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h > index 1d58da946739..f20ac7a6efa4 100644 > --- a/arch/powerpc/include/asm/paca.h > +++ b/arch/powerpc/include/asm/paca.h > @@ -278,6 +278,11 @@ struct paca_struct { > struct mce_info *mce_info; > u8 mce_pending_irq_work; > #endif /* CONFIG_PPC_BOOK3S_64 */ > +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE > + u64 l1_to_l2_cs; > + u64 l2_to_l1_cs; > + u64 l2_runtime_agg; > +#endif > } ____cacheline_aligned; I don't think these really need to be in the paca. paca is for per-cpu stuff that is accessed in real mode, early interrupt entry, etc. > > extern void copy_mm_to_paca(struct mm_struct *mm); > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 8e86eb577eb8..ed69ad58bd02 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -4108,6 +4108,54 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu) > } > } > > +static inline int kvmhv_get_l2_counters_status(void) > +{ > + return get_lppaca()->l2_counters_enable; > +} > + > +static inline void kvmhv_set_l2_counters_status(int cpu, bool status) > +{ > + if (status) > + lppaca_of(cpu).l2_counters_enable = 1; > + else > + lppaca_of(cpu).l2_counters_enable = 0; > +} > + > +int kmvhv_counters_tracepoint_regfunc(void) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) { > + kvmhv_set_l2_counters_status(cpu, true); > + } > + return 0; > +} > + > +void kmvhv_counters_tracepoint_unregfunc(void) > +{ > + int cpu; > + > + for_each_possible_cpu(cpu) { > + kvmhv_set_l2_counters_status(cpu, false); > + } > +} > + > +static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu) > +{ > + struct lppaca *lp = get_lppaca(); > + u64 l1_to_l2_ns, l2_to_l1_ns, l2_runtime_ns; > + > + l1_to_l2_ns = tb_to_ns(be64_to_cpu(lp->l1_to_l2_cs_tb)); > + l2_to_l1_ns = tb_to_ns(be64_to_cpu(lp->l2_to_l1_cs_tb)); > + l2_runtime_ns = tb_to_ns(be64_to_cpu(lp->l2_runtime_tb)); > + trace_kvmppc_vcpu_stats(vcpu, l1_to_l2_ns - local_paca->l1_to_l2_cs, > + l2_to_l1_ns - local_paca->l2_to_l1_cs, > + l2_runtime_ns - local_paca->l2_runtime_agg); > + local_paca->l1_to_l2_cs = l1_to_l2_ns; > + local_paca->l2_to_l1_cs = l2_to_l1_ns; > + local_paca->l2_runtime_agg = l2_runtime_ns; > +} So you're just using the per-cpu values to cache the last value read so next time you can take a delta. Could you zero the counters before entry? Or just use local variables to read the before values. If you want to keep the same scheme, I think per-cpu variables should work. Otherwise, Reviewed-by: Nicholas Piggin <npiggin@gmail.com> > + > static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, > unsigned long lpcr, u64 *tb) > { > @@ -4156,6 +4204,10 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, > > timer_rearm_host_dec(*tb); > > + /* Record context switch and guest_run_time data */ > + if (kvmhv_get_l2_counters_status()) > + do_trace_nested_cs_time(vcpu); > + > return trap; > } > > diff --git a/arch/powerpc/kvm/trace_hv.h b/arch/powerpc/kvm/trace_hv.h > index 8d57c8428531..dc118ab88f23 100644 > --- a/arch/powerpc/kvm/trace_hv.h > +++ b/arch/powerpc/kvm/trace_hv.h > @@ -238,6 +238,9 @@ > {H_MULTI_THREADS_ACTIVE, "H_MULTI_THREADS_ACTIVE"}, \ > {H_OUTSTANDING_COP_OPS, "H_OUTSTANDING_COP_OPS"} > > +int kmvhv_counters_tracepoint_regfunc(void); > +void kmvhv_counters_tracepoint_unregfunc(void); > + > TRACE_EVENT(kvm_guest_enter, > TP_PROTO(struct kvm_vcpu *vcpu), > TP_ARGS(vcpu), > @@ -512,6 +515,30 @@ TRACE_EVENT(kvmppc_run_vcpu_exit, > __entry->vcpu_id, __entry->exit, __entry->ret) > ); > > +TRACE_EVENT_FN(kvmppc_vcpu_stats, > + TP_PROTO(struct kvm_vcpu *vcpu, u64 l1_to_l2_cs, u64 l2_to_l1_cs, u64 l2_runtime), > + > + TP_ARGS(vcpu, l1_to_l2_cs, l2_to_l1_cs, l2_runtime), > + > + TP_STRUCT__entry( > + __field(int, vcpu_id) > + __field(u64, l1_to_l2_cs) > + __field(u64, l2_to_l1_cs) > + __field(u64, l2_runtime) > + ), > + > + TP_fast_assign( > + __entry->vcpu_id = vcpu->vcpu_id; > + __entry->l1_to_l2_cs = l1_to_l2_cs; > + __entry->l2_to_l1_cs = l2_to_l1_cs; > + __entry->l2_runtime = l2_runtime; > + ), > + > + TP_printk("VCPU %d: l1_to_l2_cs_time=%llu ns l2_to_l1_cs_time=%llu ns l2_runtime=%llu ns", > + __entry->vcpu_id, __entry->l1_to_l2_cs, > + __entry->l2_to_l1_cs, __entry->l2_runtime), > + kmvhv_counters_tracepoint_regfunc, kmvhv_counters_tracepoint_unregfunc > +); > #endif /* _TRACE_KVM_HV_H */ > > /* This part must be outside protection */
Gautam Menghani <gautam@linux.ibm.com> writes: > PAPR hypervisor has introduced three new counters in the VPA area of > LPAR CPUs for KVM L2 guest (see [1] for terminology) observability - 2 > for context switches from host to guest and vice versa, and 1 counter > for getting the total time spent inside the KVM guest. Add a tracepoint > that enables reading the counters for use by ftrace/perf. Note that this > tracepoint is only available for nestedv2 API (i.e, KVM on PowerVM). ... > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 8e86eb577eb8..ed69ad58bd02 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -4108,6 +4108,54 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu) > } > } > > +static inline int kvmhv_get_l2_counters_status(void) > +{ > + return get_lppaca()->l2_counters_enable; > +} This is breaking the powernv build: $ make powernv_defconfig ; make -s -j (nproc) make[1]: Entering directory '/home/michael/linux/.build' GEN Makefile # # configuration written to .config # make[1]: Leaving directory '/home/michael/linux/.build' ../arch/powerpc/kvm/book3s_hv.c: In function ‘kvmhv_get_l2_counters_status’: ../arch/powerpc/kvm/book3s_hv.c:4113:16: error: implicit declaration of function ‘get_lppaca’; did you mean ‘get_paca’? [-Werror=implicit-function-declaration] 4113 | return get_lppaca()->l2_counters_enable; | ^~~~~~~~~~ | get_paca ../arch/powerpc/kvm/book3s_hv.c:4113:28: error: invalid type argument of ‘->’ (have ‘int’) 4113 | return get_lppaca()->l2_counters_enable; | ^~ In file included from ../arch/powerpc/include/asm/paravirt.h:9, from ../arch/powerpc/include/asm/qspinlock.h:7, from ../arch/powerpc/include/asm/spinlock.h:7, from ../include/linux/spinlock.h:95, from ../include/linux/sched.h:2138, from ../include/linux/hardirq.h:9, from ../include/linux/kvm_host.h:7, from ../arch/powerpc/kvm/book3s_hv.c:18: ../arch/powerpc/kvm/book3s_hv.c: In function ‘kvmhv_set_l2_counters_status’: ../arch/powerpc/include/asm/lppaca.h:105:41: error: ‘struct paca_struct’ has no member named ‘lppaca_ptr’ 105 | #define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr) | ^~ ../arch/powerpc/kvm/book3s_hv.c:4119:17: note: in expansion of macro ‘lppaca_of’ 4119 | lppaca_of(cpu).l2_counters_enable = 1; | ^~~~~~~~~ ../arch/powerpc/include/asm/lppaca.h:105:41: error: ‘struct paca_struct’ has no member named ‘lppaca_ptr’ 105 | #define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr) | ^~ ../arch/powerpc/kvm/book3s_hv.c:4121:17: note: in expansion of macro ‘lppaca_of’ 4121 | lppaca_of(cpu).l2_counters_enable = 0; | ^~~~~~~~~ ../arch/powerpc/kvm/book3s_hv.c: In function ‘do_trace_nested_cs_time’: ../arch/powerpc/kvm/book3s_hv.c:4145:29: error: initialization of ‘struct lppaca *’ from ‘int’ makes pointer from integer without a cast [-Werror=int-conversion] 4145 | struct lppaca *lp = get_lppaca(); | ^~~~~~~~~~ ../arch/powerpc/kvm/book3s_hv.c: In function ‘kvmhv_get_l2_counters_status’: ../arch/powerpc/kvm/book3s_hv.c:4114:1: error: control reaches end of non-void function [-Werror=return-type] 4114 | } | ^ cc1: all warnings being treated as errors make[5]: *** [../scripts/Makefile.build:244: arch/powerpc/kvm/book3s_hv.o] Error 1 make[5]: *** Waiting for unfinished jobs.... make[4]: *** [../scripts/Makefile.build:485: arch/powerpc/kvm] Error 2 make[4]: *** Waiting for unfinished jobs.... make[3]: *** [../scripts/Makefile.build:485: arch/powerpc] Error 2 make[3]: *** Waiting for unfinished jobs.... make[2]: *** [/home/michael/linux/Makefile:1919: .] Error 2 make[1]: *** [/home/michael/linux/Makefile:240: __sub-make] Error 2 make: *** [Makefile:240: __sub-make] Error 2 cheers
On Wed May 8, 2024 at 10:36 PM AEST, Michael Ellerman wrote: > Gautam Menghani <gautam@linux.ibm.com> writes: > > PAPR hypervisor has introduced three new counters in the VPA area of > > LPAR CPUs for KVM L2 guest (see [1] for terminology) observability - 2 > > for context switches from host to guest and vice versa, and 1 counter > > for getting the total time spent inside the KVM guest. Add a tracepoint > > that enables reading the counters for use by ftrace/perf. Note that this > > tracepoint is only available for nestedv2 API (i.e, KVM on PowerVM). > ... > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > > index 8e86eb577eb8..ed69ad58bd02 100644 > > --- a/arch/powerpc/kvm/book3s_hv.c > > +++ b/arch/powerpc/kvm/book3s_hv.c > > @@ -4108,6 +4108,54 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu) > > } > > } > > > > +static inline int kvmhv_get_l2_counters_status(void) > > +{ > > + return get_lppaca()->l2_counters_enable; > > +} > > This is breaking the powernv build: [...] All the nested KVM code should really go under CONFIG_PSERIES. Possibly even moved out to its own file. For now maybe you could just ifdef these few functions and replace with noop variants for !PSERIES. Thanks, Nick
diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h index 61ec2447dabf..f40a646bee3c 100644 --- a/arch/powerpc/include/asm/lppaca.h +++ b/arch/powerpc/include/asm/lppaca.h @@ -62,7 +62,8 @@ struct lppaca { u8 donate_dedicated_cpu; /* Donate dedicated CPU cycles */ u8 fpregs_in_use; u8 pmcregs_in_use; - u8 reserved8[28]; + u8 l2_counters_enable; /* Enable usage of counters for KVM guest */ + u8 reserved8[27]; __be64 wait_state_cycles; /* Wait cycles for this proc */ u8 reserved9[28]; __be16 slb_count; /* # of SLBs to maintain */ @@ -92,9 +93,13 @@ struct lppaca { /* cacheline 4-5 */ __be32 page_ins; /* CMO Hint - # page ins by OS */ - u8 reserved12[148]; + u8 reserved12[28]; + volatile __be64 l1_to_l2_cs_tb; + volatile __be64 l2_to_l1_cs_tb; + volatile __be64 l2_runtime_tb; + u8 reserved13[96]; volatile __be64 dtl_idx; /* Dispatch Trace Log head index */ - u8 reserved13[96]; + u8 reserved14[96]; } ____cacheline_aligned; #define lppaca_of(cpu) (*paca_ptrs[cpu]->lppaca_ptr) diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h index 1d58da946739..f20ac7a6efa4 100644 --- a/arch/powerpc/include/asm/paca.h +++ b/arch/powerpc/include/asm/paca.h @@ -278,6 +278,11 @@ struct paca_struct { struct mce_info *mce_info; u8 mce_pending_irq_work; #endif /* CONFIG_PPC_BOOK3S_64 */ +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE + u64 l1_to_l2_cs; + u64 l2_to_l1_cs; + u64 l2_runtime_agg; +#endif } ____cacheline_aligned; extern void copy_mm_to_paca(struct mm_struct *mm); diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 8e86eb577eb8..ed69ad58bd02 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -4108,6 +4108,54 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu) } } +static inline int kvmhv_get_l2_counters_status(void) +{ + return get_lppaca()->l2_counters_enable; +} + +static inline void kvmhv_set_l2_counters_status(int cpu, bool status) +{ + if (status) + lppaca_of(cpu).l2_counters_enable = 1; + else + lppaca_of(cpu).l2_counters_enable = 0; +} + +int kmvhv_counters_tracepoint_regfunc(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + kvmhv_set_l2_counters_status(cpu, true); + } + return 0; +} + +void kmvhv_counters_tracepoint_unregfunc(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + kvmhv_set_l2_counters_status(cpu, false); + } +} + +static void do_trace_nested_cs_time(struct kvm_vcpu *vcpu) +{ + struct lppaca *lp = get_lppaca(); + u64 l1_to_l2_ns, l2_to_l1_ns, l2_runtime_ns; + + l1_to_l2_ns = tb_to_ns(be64_to_cpu(lp->l1_to_l2_cs_tb)); + l2_to_l1_ns = tb_to_ns(be64_to_cpu(lp->l2_to_l1_cs_tb)); + l2_runtime_ns = tb_to_ns(be64_to_cpu(lp->l2_runtime_tb)); + trace_kvmppc_vcpu_stats(vcpu, l1_to_l2_ns - local_paca->l1_to_l2_cs, + l2_to_l1_ns - local_paca->l2_to_l1_cs, + l2_runtime_ns - local_paca->l2_runtime_agg); + local_paca->l1_to_l2_cs = l1_to_l2_ns; + local_paca->l2_to_l1_cs = l2_to_l1_ns; + local_paca->l2_runtime_agg = l2_runtime_ns; +} + static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb) { @@ -4156,6 +4204,10 @@ static int kvmhv_vcpu_entry_nestedv2(struct kvm_vcpu *vcpu, u64 time_limit, timer_rearm_host_dec(*tb); + /* Record context switch and guest_run_time data */ + if (kvmhv_get_l2_counters_status()) + do_trace_nested_cs_time(vcpu); + return trap; } diff --git a/arch/powerpc/kvm/trace_hv.h b/arch/powerpc/kvm/trace_hv.h index 8d57c8428531..dc118ab88f23 100644 --- a/arch/powerpc/kvm/trace_hv.h +++ b/arch/powerpc/kvm/trace_hv.h @@ -238,6 +238,9 @@ {H_MULTI_THREADS_ACTIVE, "H_MULTI_THREADS_ACTIVE"}, \ {H_OUTSTANDING_COP_OPS, "H_OUTSTANDING_COP_OPS"} +int kmvhv_counters_tracepoint_regfunc(void); +void kmvhv_counters_tracepoint_unregfunc(void); + TRACE_EVENT(kvm_guest_enter, TP_PROTO(struct kvm_vcpu *vcpu), TP_ARGS(vcpu), @@ -512,6 +515,30 @@ TRACE_EVENT(kvmppc_run_vcpu_exit, __entry->vcpu_id, __entry->exit, __entry->ret) ); +TRACE_EVENT_FN(kvmppc_vcpu_stats, + TP_PROTO(struct kvm_vcpu *vcpu, u64 l1_to_l2_cs, u64 l2_to_l1_cs, u64 l2_runtime), + + TP_ARGS(vcpu, l1_to_l2_cs, l2_to_l1_cs, l2_runtime), + + TP_STRUCT__entry( + __field(int, vcpu_id) + __field(u64, l1_to_l2_cs) + __field(u64, l2_to_l1_cs) + __field(u64, l2_runtime) + ), + + TP_fast_assign( + __entry->vcpu_id = vcpu->vcpu_id; + __entry->l1_to_l2_cs = l1_to_l2_cs; + __entry->l2_to_l1_cs = l2_to_l1_cs; + __entry->l2_runtime = l2_runtime; + ), + + TP_printk("VCPU %d: l1_to_l2_cs_time=%llu ns l2_to_l1_cs_time=%llu ns l2_runtime=%llu ns", + __entry->vcpu_id, __entry->l1_to_l2_cs, + __entry->l2_to_l1_cs, __entry->l2_runtime), + kmvhv_counters_tracepoint_regfunc, kmvhv_counters_tracepoint_unregfunc +); #endif /* _TRACE_KVM_HV_H */ /* This part must be outside protection */