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Message-ID: <CAOnJCU+=A1GXvaQis5RrDabPAvAZccmc9HF1KU4ReuRTSx5pCQ@mail.gmail.com>
Date: Tue, 31 Jan 2023 14:46:36 -0800
From: Atish Patra <atishp@...shpatra.org>
To: Anup Patel <anup@...infault.org>
Cc: Atish Patra <atishp@...osinc.com>, linux-kernel@...r.kernel.org,
Andrew Jones <ajones@...tanamicro.com>,
Guo Ren <guoren@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org,
linux-riscv@...ts.infradead.org,
Mark Rutland <mark.rutland@....com>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Sergey Matyukevich <sergey.matyukevich@...tacore.com>,
Will Deacon <will@...nel.org>
Subject: Re: [PATCH v3 11/14] RISC-V: KVM: Implement trap & emulate for hpmcounters
On Sun, Jan 29, 2023 at 4:44 AM Anup Patel <anup@...infault.org> wrote:
>
> On Fri, Jan 27, 2023 at 11:56 PM Atish Patra <atishp@...osinc.com> wrote:
> >
> > As the KVM guests only see the virtual PMU counters, all hpmcounter
> > access should trap and KVM emulates the read access on behalf of guests.
> >
> > Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
> > Signed-off-by: Atish Patra <atishp@...osinc.com>
> > ---
> > arch/riscv/include/asm/kvm_vcpu_pmu.h | 16 ++++++++++
> > arch/riscv/kvm/vcpu_insn.c | 4 ++-
> > arch/riscv/kvm/vcpu_pmu.c | 45 ++++++++++++++++++++++++++-
> > 3 files changed, 63 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> > index 3f43a43..022d45d 100644
> > --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h
> > +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> > @@ -43,6 +43,19 @@ struct kvm_pmu {
> > #define vcpu_to_pmu(vcpu) (&(vcpu)->arch.pmu)
> > #define pmu_to_vcpu(pmu) (container_of((pmu), struct kvm_vcpu, arch.pmu))
> >
> > +#if defined(CONFIG_32BIT)
> > +#define KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS \
> > +{ .base = CSR_CYCLEH, .count = 31, .func = kvm_riscv_vcpu_pmu_read_hpm }, \
> > +{ .base = CSR_CYCLE, .count = 31, .func = kvm_riscv_vcpu_pmu_read_hpm },
> > +#else
> > +#define KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS \
> > +{ .base = CSR_CYCLE, .count = 31, .func = kvm_riscv_vcpu_pmu_read_hpm },
> > +#endif
> > +
> > +int kvm_riscv_vcpu_pmu_read_hpm(struct kvm_vcpu *vcpu, unsigned int csr_num,
> > + unsigned long *val, unsigned long new_val,
> > + unsigned long wr_mask);
> > +
> > int kvm_riscv_vcpu_pmu_num_ctrs(struct kvm_vcpu *vcpu, struct kvm_vcpu_sbi_ext_data *edata);
> > int kvm_riscv_vcpu_pmu_ctr_info(struct kvm_vcpu *vcpu, unsigned long cidx,
> > struct kvm_vcpu_sbi_ext_data *edata);
> > @@ -65,6 +78,9 @@ void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu);
> > #else
> > struct kvm_pmu {
> > };
> > +#define KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS \
> > +{ .base = 0, .count = 0, .func = NULL },
> > +
>
> Redundant newline here.
>
Fixed.
> >
> > static inline int kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
> > {
> > diff --git a/arch/riscv/kvm/vcpu_insn.c b/arch/riscv/kvm/vcpu_insn.c
> > index 0bb5276..f689337 100644
> > --- a/arch/riscv/kvm/vcpu_insn.c
> > +++ b/arch/riscv/kvm/vcpu_insn.c
> > @@ -213,7 +213,9 @@ struct csr_func {
> > unsigned long wr_mask);
> > };
> >
> > -static const struct csr_func csr_funcs[] = { };
> > +static const struct csr_func csr_funcs[] = {
> > + KVM_RISCV_VCPU_HPMCOUNTER_CSR_FUNCS
> > +};
> >
> > /**
> > * kvm_riscv_vcpu_csr_return -- Handle CSR read/write after user space
> > diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> > index 7713927..894053a 100644
> > --- a/arch/riscv/kvm/vcpu_pmu.c
> > +++ b/arch/riscv/kvm/vcpu_pmu.c
> > @@ -17,6 +17,44 @@
> >
> > #define kvm_pmu_num_counters(pmu) ((pmu)->num_hw_ctrs + (pmu)->num_fw_ctrs)
> >
> > +static int pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
> > + unsigned long *out_val)
> > +{
> > + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> > + struct kvm_pmc *pmc;
> > + u64 enabled, running;
> > +
> > + pmc = &kvpmu->pmc[cidx];
> > + if (!pmc->perf_event)
> > + return -EINVAL;
> > +
> > + pmc->counter_val += perf_event_read_value(pmc->perf_event, &enabled, &running);
> > + *out_val = pmc->counter_val;
> > +
> > + return 0;
> > +}
> > +
> > +int kvm_riscv_vcpu_pmu_read_hpm(struct kvm_vcpu *vcpu, unsigned int csr_num,
> > + unsigned long *val, unsigned long new_val,
> > + unsigned long wr_mask)
> > +{
> > + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> > + int cidx, ret = KVM_INSN_CONTINUE_NEXT_SEPC;
> > +
> > + if (!kvpmu || !kvpmu->init_done)
> > + return KVM_INSN_EXIT_TO_USER_SPACE;
>
> As discussed previously, this should be KVM_INSN_ILLEGAL_TRAP.
>
Done.
> > +
> > + if (wr_mask)
> > + return KVM_INSN_ILLEGAL_TRAP;
> > +
> > + cidx = csr_num - CSR_CYCLE;
> > +
> > + if (pmu_ctr_read(vcpu, cidx, val) < 0)
> > + return KVM_INSN_EXIT_TO_USER_SPACE;
>
> Same as above.
>
Done.
> > +
> > + return ret;
> > +}
> > +
> > int kvm_riscv_vcpu_pmu_num_ctrs(struct kvm_vcpu *vcpu, struct kvm_vcpu_sbi_ext_data *edata)
> > {
> > struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> > @@ -69,7 +107,12 @@ int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_ba
> > int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
> > struct kvm_vcpu_sbi_ext_data *edata)
> > {
> > - /* TODO */
> > + int ret;
> > +
> > + ret = pmu_ctr_read(vcpu, cidx, &edata->out_val);
> > + if (ret == -EINVAL)
> > + edata->err_val = SBI_ERR_INVALID_PARAM;
> > +
> > return 0;
> > }
> >
> > --
> > 2.25.1
> >
>
> Regards,
> Anup
--
Regards,
Atish
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