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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2023 Rivos Inc
*
* Authors:
* Atish Patra <atishp@rivosinc.com>
*/
#define pr_fmt(fmt) "riscv-kvm-pmu: " fmt
#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>
#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) {
/*
* In absence of sscofpmf in the platform, the guest OS may use
* the legacy PMU driver to read cycle/instret. In that case,
* just return 0 to avoid any illegal trap. However, any other
* hpmcounter access should result in illegal trap as they must
* be access through SBI PMU only.
*/
if (csr_num == CSR_CYCLE || csr_num == CSR_INSTRET) {
*val = 0;
return ret;
} else {
return KVM_INSN_ILLEGAL_TRAP;
}
}
/* The counter CSR are read only. Thus, any write should result in illegal traps */
if (wr_mask)
return KVM_INSN_ILLEGAL_TRAP;
cidx = csr_num - CSR_CYCLE;
if (pmu_ctr_read(vcpu, cidx, val) < 0)
return KVM_INSN_ILLEGAL_TRAP;
return ret;
}
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_KVM_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 flags, u64 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 flags,
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 flags,
unsigned long eidx, u64 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)
{
int ret;
ret = pmu_ctr_read(vcpu, cidx, &retdata->out_val);
if (ret == -EINVAL)
retdata->err_val = SBI_ERR_INVALID_PARAM;
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;
/*
* PMU functionality should be only available to guests if privilege mode
* filtering is available in the host. Otherwise, guest will always count
* events while the execution is in hypervisor mode.
*/
if (!riscv_isa_extension_available(NULL, SSCOFPMF))
return;
ret = riscv_pmu_get_hpm_info(&hpm_width, &num_hw_ctrs);
if (ret < 0 || !hpm_width || !num_hw_ctrs)
return;
/*
* Increase the number of hardware counters to offset the time counter.
*/
kvpmu->num_hw_ctrs = num_hw_ctrs + 1;
kvpmu->num_fw_ctrs = SBI_PMU_FW_MAX;
if (kvpmu->num_hw_ctrs > RISCV_KVM_MAX_HW_CTRS) {
pr_warn_once("Limiting the hardware counters to 32 as specified by the ISA");
kvpmu->num_hw_ctrs = RISCV_KVM_MAX_HW_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);
}
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