| Message ID | 20240403080452.1007601-12-atishp@rivosinc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | RISC-V SBI v2.0 PMU improvements and Perf sampling in KVM guest | expand |
On Wed, Apr 03, 2024 at 01:04:40AM -0700, Atish Patra wrote: > Currently, we return a linux error code if creating a perf event failed > in kvm. That shouldn't be necessary as guest can continue to operate > without perf profiling or profiling with firmware counters. > > Return appropriate SBI error code to indicate that PMU configuration > failed. An error message in kvm already describes the reason for failure. > > Fixes: 0cb74b65d2e5 ("RISC-V: KVM: Implement perf support without sampling") > Reviewed-by: Anup Patel <anup@brainfault.org> > Signed-off-by: Atish Patra <atishp@rivosinc.com> > --- > arch/riscv/kvm/vcpu_pmu.c | 14 +++++++++----- > arch/riscv/kvm/vcpu_sbi_pmu.c | 6 +++--- > 2 files changed, 12 insertions(+), 8 deletions(-) > > diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c > index b5159ce4592d..2d9929bbc2c8 100644 > --- a/arch/riscv/kvm/vcpu_pmu.c > +++ b/arch/riscv/kvm/vcpu_pmu.c > @@ -229,8 +229,9 @@ static int kvm_pmu_validate_counter_mask(struct kvm_pmu *kvpmu, unsigned long ct > return 0; > } > > -static int kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_attr *attr, > - unsigned long flags, unsigned long eidx, unsigned long evtdata) > +static long kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_attr *attr, > + unsigned long flags, unsigned long eidx, > + unsigned long evtdata) > { > struct perf_event *event; > > @@ -454,7 +455,8 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba > unsigned long eidx, u64 evtdata, > struct kvm_vcpu_sbi_return *retdata) > { > - int ctr_idx, ret, sbiret = 0; > + int ctr_idx, sbiret = 0; > + long ret; > bool is_fevent; > unsigned long event_code; > u32 etype = kvm_pmu_get_perf_event_type(eidx); > @@ -513,8 +515,10 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba > kvpmu->fw_event[event_code].started = true; > } else { > ret = kvm_pmu_create_perf_event(pmc, &attr, flags, eidx, evtdata); > - if (ret) > - return ret; > + if (ret) { > + sbiret = SBI_ERR_NOT_SUPPORTED; I'm still not sure about this. I replied in the v4 thread about it. Thanks, drew > + goto out; > + } > } > > set_bit(ctr_idx, kvpmu->pmc_in_use); > diff --git a/arch/riscv/kvm/vcpu_sbi_pmu.c b/arch/riscv/kvm/vcpu_sbi_pmu.c > index 7eca72df2cbd..e1633606c98b 100644 > --- a/arch/riscv/kvm/vcpu_sbi_pmu.c > +++ b/arch/riscv/kvm/vcpu_sbi_pmu.c > @@ -42,9 +42,9 @@ static int kvm_sbi_ext_pmu_handler(struct kvm_vcpu *vcpu, struct kvm_run *run, > #endif > /* > * This can fail if perf core framework fails to create an event. > - * Forward the error to userspace because it's an error which > - * happened within the host kernel. The other option would be > - * to convert to an SBI error and forward to the guest. > + * No need to forward the error to userspace and exit the guest. > + * The operation can continue without profiling. Forward the > + * appropriate SBI error to the guest. > */ > ret = kvm_riscv_vcpu_pmu_ctr_cfg_match(vcpu, cp->a0, cp->a1, > cp->a2, cp->a3, temp, retdata); > -- > 2.34.1 >
diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c index b5159ce4592d..2d9929bbc2c8 100644 --- a/arch/riscv/kvm/vcpu_pmu.c +++ b/arch/riscv/kvm/vcpu_pmu.c @@ -229,8 +229,9 @@ static int kvm_pmu_validate_counter_mask(struct kvm_pmu *kvpmu, unsigned long ct return 0; } -static int kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_attr *attr, - unsigned long flags, unsigned long eidx, unsigned long evtdata) +static long kvm_pmu_create_perf_event(struct kvm_pmc *pmc, struct perf_event_attr *attr, + unsigned long flags, unsigned long eidx, + unsigned long evtdata) { struct perf_event *event; @@ -454,7 +455,8 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba unsigned long eidx, u64 evtdata, struct kvm_vcpu_sbi_return *retdata) { - int ctr_idx, ret, sbiret = 0; + int ctr_idx, sbiret = 0; + long ret; bool is_fevent; unsigned long event_code; u32 etype = kvm_pmu_get_perf_event_type(eidx); @@ -513,8 +515,10 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba kvpmu->fw_event[event_code].started = true; } else { ret = kvm_pmu_create_perf_event(pmc, &attr, flags, eidx, evtdata); - if (ret) - return ret; + if (ret) { + sbiret = SBI_ERR_NOT_SUPPORTED; + goto out; + } } set_bit(ctr_idx, kvpmu->pmc_in_use); diff --git a/arch/riscv/kvm/vcpu_sbi_pmu.c b/arch/riscv/kvm/vcpu_sbi_pmu.c index 7eca72df2cbd..e1633606c98b 100644 --- a/arch/riscv/kvm/vcpu_sbi_pmu.c +++ b/arch/riscv/kvm/vcpu_sbi_pmu.c @@ -42,9 +42,9 @@ static int kvm_sbi_ext_pmu_handler(struct kvm_vcpu *vcpu, struct kvm_run *run, #endif /* * This can fail if perf core framework fails to create an event. - * Forward the error to userspace because it's an error which - * happened within the host kernel. The other option would be - * to convert to an SBI error and forward to the guest. + * No need to forward the error to userspace and exit the guest. + * The operation can continue without profiling. Forward the + * appropriate SBI error to the guest. */ ret = kvm_riscv_vcpu_pmu_ctr_cfg_match(vcpu, cp->a0, cp->a1, cp->a2, cp->a3, temp, retdata);
Currently, we return a linux error code if creating a perf event failed in kvm. That shouldn't be necessary as guest can continue to operate without perf profiling or profiling with firmware counters. Return appropriate SBI error code to indicate that PMU configuration failed. An error message in kvm already describes the reason for failure. Fixes: 0cb74b65d2e5 ("RISC-V: KVM: Implement perf support without sampling") Reviewed-by: Anup Patel <anup@brainfault.org> Signed-off-by: Atish Patra <atishp@rivosinc.com> --- arch/riscv/kvm/vcpu_pmu.c | 14 +++++++++----- arch/riscv/kvm/vcpu_sbi_pmu.c | 6 +++--- 2 files changed, 12 insertions(+), 8 deletions(-)