Re: [PATCH v4 07/14] RISC-V: KVM: Add skeleton support for perf

From: Anup Patel
Date: Wed Feb 01 2023 - 23:03:19 EST

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In reply to: Atish Patra: "[PATCH v4 07/14] RISC-V: KVM: Add skeleton support for perf"
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On Thu, Feb 2, 2023 at 4:42 AM Atish Patra <atishp@xxxxxxxxxxxx> wrote:
>
> This patch only adds barebone structure of perf implementation. Most of
> the function returns zero at this point and will be implemented
> fully in the future.
>
> Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>

Looks good to me.

Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>

Regards,
Anup

> ---
> arch/riscv/include/asm/kvm_host.h | 4 +
> arch/riscv/include/asm/kvm_vcpu_pmu.h | 78 +++++++++++++++
> arch/riscv/kvm/Makefile | 1 +
> arch/riscv/kvm/vcpu.c | 7 ++
> arch/riscv/kvm/vcpu_pmu.c | 136 ++++++++++++++++++++++++++
> 5 files changed, 226 insertions(+)
> create mode 100644 arch/riscv/include/asm/kvm_vcpu_pmu.h
> create mode 100644 arch/riscv/kvm/vcpu_pmu.c
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 93f43a3..b90be9a 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -18,6 +18,7 @@
> #include <asm/kvm_vcpu_insn.h>
> #include <asm/kvm_vcpu_sbi.h>
> #include <asm/kvm_vcpu_timer.h>
> +#include <asm/kvm_vcpu_pmu.h>
>
> #define KVM_MAX_VCPUS 1024
>
> @@ -228,6 +229,9 @@ struct kvm_vcpu_arch {
>
> /* Don't run the VCPU (blocked) */
> bool pause;
> +
> + /* Performance monitoring context */
> + struct kvm_pmu pmu_context;
> };
>
> static inline void kvm_arch_hardware_unsetup(void) {}
> diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> new file mode 100644
> index 0000000..e2b4038
> --- /dev/null
> +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> @@ -0,0 +1,78 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2023 Rivos Inc
> + *
> + * Authors:
> + * Atish Patra <atishp@xxxxxxxxxxxx>
> + */
> +
> +#ifndef __KVM_VCPU_RISCV_PMU_H
> +#define __KVM_VCPU_RISCV_PMU_H
> +
> +#include <linux/perf/riscv_pmu.h>
> +#include <asm/kvm_vcpu_sbi.h>
> +#include <asm/sbi.h>
> +
> +#ifdef CONFIG_RISCV_PMU_SBI
> +#define RISCV_KVM_MAX_FW_CTRS 32
> +
> +#if RISCV_KVM_MAX_FW_CTRS > 32
> +#error "Maximum firmware counter can't exceed 32 without increasing the RISCV_MAX_COUNTERS"
> +#endif
> +
> +#define RISCV_MAX_COUNTERS 64
> +
> +/* Per virtual pmu counter data */
> +struct kvm_pmc {
> + u8 idx;
> + struct perf_event *perf_event;
> + uint64_t counter_val;
> + union sbi_pmu_ctr_info cinfo;
> + /* Event monitoring status */
> + bool started;
> +};
> +
> +/* PMU data structure per vcpu */
> +struct kvm_pmu {
> + struct kvm_pmc pmc[RISCV_MAX_COUNTERS];
> + /* Number of the virtual firmware counters available */
> + int num_fw_ctrs;
> + /* Number of the virtual hardware counters available */
> + int num_hw_ctrs;
> + /* A flag to indicate that pmu initialization is done */
> + bool init_done;
> + /* Bit map of all the virtual counter used */
> + DECLARE_BITMAP(pmc_in_use, RISCV_MAX_COUNTERS);
> +};
> +
> +#define vcpu_to_pmu(vcpu) (&(vcpu)->arch.pmu_context)
> +#define pmu_to_vcpu(pmu) (container_of((pmu), struct kvm_vcpu, arch.pmu_context))
> +
> +int kvm_riscv_vcpu_pmu_num_ctrs(struct kvm_vcpu *vcpu, struct kvm_vcpu_sbi_return *retdata);
> +int kvm_riscv_vcpu_pmu_ctr_info(struct kvm_vcpu *vcpu, unsigned long cidx,
> + struct kvm_vcpu_sbi_return *retdata);
> +int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> + unsigned long ctr_mask, unsigned long flag, uint64_t ival,
> + struct kvm_vcpu_sbi_return *retdata);
> +int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> + unsigned long ctr_mask, unsigned long flag,
> + struct kvm_vcpu_sbi_return *retdata);
> +int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> + unsigned long ctr_mask, unsigned long flag,
> + unsigned long eidx, uint64_t evtdata,
> + struct kvm_vcpu_sbi_return *retdata);
> +int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
> + struct kvm_vcpu_sbi_return *retdata);
> +void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu);
> +void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu);
> +void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu);
> +
> +#else
> +struct kvm_pmu {
> +};
> +
> +static inline void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu) {}
> +static inline void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu) {}
> +static inline void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu) {}
> +#endif /* CONFIG_RISCV_PMU_SBI */
> +#endif /* !__KVM_VCPU_RISCV_PMU_H */
> diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
> index 019df920..5de1053 100644
> --- a/arch/riscv/kvm/Makefile
> +++ b/arch/riscv/kvm/Makefile
> @@ -25,3 +25,4 @@ kvm-y += vcpu_sbi_base.o
> kvm-y += vcpu_sbi_replace.o
> kvm-y += vcpu_sbi_hsm.o
> kvm-y += vcpu_timer.o
> +kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 7c08567..7d010b0 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -138,6 +138,8 @@ static void kvm_riscv_reset_vcpu(struct kvm_vcpu *vcpu)
> WRITE_ONCE(vcpu->arch.irqs_pending, 0);
> WRITE_ONCE(vcpu->arch.irqs_pending_mask, 0);
>
> + kvm_riscv_vcpu_pmu_reset(vcpu);
> +
> vcpu->arch.hfence_head = 0;
> vcpu->arch.hfence_tail = 0;
> memset(vcpu->arch.hfence_queue, 0, sizeof(vcpu->arch.hfence_queue));
> @@ -194,6 +196,9 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> /* Setup VCPU timer */
> kvm_riscv_vcpu_timer_init(vcpu);
>
> + /* setup performance monitoring */
> + kvm_riscv_vcpu_pmu_init(vcpu);
> +
> /* Reset VCPU */
> kvm_riscv_reset_vcpu(vcpu);
>
> @@ -216,6 +221,8 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
> /* Cleanup VCPU timer */
> kvm_riscv_vcpu_timer_deinit(vcpu);
>
> + kvm_riscv_vcpu_pmu_deinit(vcpu);
> +
> /* Free unused pages pre-allocated for G-stage page table mappings */
> kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
> }
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> new file mode 100644
> index 0000000..2dad37f
> --- /dev/null
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -0,0 +1,136 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023 Rivos Inc
> + *
> + * Authors:
> + * Atish Patra <atishp@xxxxxxxxxxxx>
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/kvm_host.h>
> +#include <linux/perf/riscv_pmu.h>
> +#include <asm/csr.h>
> +#include <asm/kvm_vcpu_sbi.h>
> +#include <asm/kvm_vcpu_pmu.h>
> +#include <linux/kvm_host.h>
> +
> +#define kvm_pmu_num_counters(pmu) ((pmu)->num_hw_ctrs + (pmu)->num_fw_ctrs)
> +
> +int kvm_riscv_vcpu_pmu_num_ctrs(struct kvm_vcpu *vcpu, struct kvm_vcpu_sbi_return *retdata)
> +{
> + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> +
> + retdata->out_val = kvm_pmu_num_counters(kvpmu);
> +
> + return 0;
> +}
> +
> +int kvm_riscv_vcpu_pmu_ctr_info(struct kvm_vcpu *vcpu, unsigned long cidx,
> + struct kvm_vcpu_sbi_return *retdata)
> +{
> + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> +
> + if (cidx > RISCV_MAX_COUNTERS || cidx == 1) {
> + retdata->err_val = SBI_ERR_INVALID_PARAM;
> + return 0;
> + }
> +
> + retdata->out_val = kvpmu->pmc[cidx].cinfo.value;
> +
> + return 0;
> +}
> +
> +int kvm_riscv_vcpu_pmu_ctr_start(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> + unsigned long ctr_mask, unsigned long flag, uint64_t ival,
> + struct kvm_vcpu_sbi_return *retdata)
> +{
> + /* TODO */
> + return 0;
> +}
> +
> +int kvm_riscv_vcpu_pmu_ctr_stop(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> + unsigned long ctr_mask, unsigned long flag,
> + struct kvm_vcpu_sbi_return *retdata)
> +{
> + /* TODO */
> + return 0;
> +}
> +
> +int kvm_riscv_vcpu_pmu_ctr_cfg_match(struct kvm_vcpu *vcpu, unsigned long ctr_base,
> + unsigned long ctr_mask, unsigned long flag,
> + unsigned long eidx, uint64_t evtdata,
> + struct kvm_vcpu_sbi_return *retdata)
> +{
> + /* TODO */
> + return 0;
> +}
> +
> +int kvm_riscv_vcpu_pmu_ctr_read(struct kvm_vcpu *vcpu, unsigned long cidx,
> + struct kvm_vcpu_sbi_return *retdata)
> +{
> + /* TODO */
> + return 0;
> +}
> +
> +void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu)
> +{
> + int i = 0, ret, num_hw_ctrs = 0, hpm_width = 0;
> + struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> + struct kvm_pmc *pmc;
> +
> + ret = riscv_pmu_get_hpm_info(&hpm_width, &num_hw_ctrs);
> + if (ret < 0 || !hpm_width || !num_hw_ctrs)
> + return;
> +
> + /*
> + * It is guranteed that RISCV_KVM_MAX_FW_CTRS can't exceed 32 as
> + * that may exceed total number of counters more than RISCV_MAX_COUNTERS
> + */
> + kvpmu->num_hw_ctrs = num_hw_ctrs;
> + kvpmu->num_fw_ctrs = RISCV_KVM_MAX_FW_CTRS;
> +
> + /*
> + * There is no correlation between the logical hardware counter and virtual counters.
> + * However, we need to encode a hpmcounter CSR in the counter info field so that
> + * KVM can trap n emulate the read. This works well in the migration use case as
> + * KVM doesn't care if the actual hpmcounter is available in the hardware or not.
> + */
> + for (i = 0; i < kvm_pmu_num_counters(kvpmu); i++) {
> + /* TIME CSR shouldn't be read from perf interface */
> + if (i == 1)
> + continue;
> + pmc = &kvpmu->pmc[i];
> + pmc->idx = i;
> + if (i < kvpmu->num_hw_ctrs) {
> + pmc->cinfo.type = SBI_PMU_CTR_TYPE_HW;
> + if (i < 3)
> + /* CY, IR counters */
> + pmc->cinfo.width = 63;
> + else
> + pmc->cinfo.width = hpm_width;
> + /*
> + * The CSR number doesn't have any relation with the logical
> + * hardware counters. The CSR numbers are encoded sequentially
> + * to avoid maintaining a map between the virtual counter
> + * and CSR number.
> + */
> + pmc->cinfo.csr = CSR_CYCLE + i;
> + } else {
> + pmc->cinfo.type = SBI_PMU_CTR_TYPE_FW;
> + pmc->cinfo.width = BITS_PER_LONG - 1;
> + }
> + }
> +
> + kvpmu->init_done = true;
> +}
> +
> +void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu)
> +{
> + /* TODO */
> +}
> +
> +void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu)
> +{
> + kvm_riscv_vcpu_pmu_deinit(vcpu);
> +}
> --
> 2.25.1
>

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In reply to: Atish Patra: "[PATCH v4 07/14] RISC-V: KVM: Add skeleton support for perf"
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