Hi Atish,
On 2024-11-19 2:29 PM, Atish Patra wrote:
> The new get_event_info funciton allows the guest to query the presence
> of multiple events with single SBI call. Currently, the perf driver
> in linux guest invokes it for all the standard SBI PMU events. Support
> the SBI function implementation in KVM as well.
>
> Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
> ---
> arch/riscv/include/asm/kvm_vcpu_pmu.h | 3 ++
> arch/riscv/kvm/vcpu_pmu.c | 67 +++++++++++++++++++++++++++++++++++
> arch/riscv/kvm/vcpu_sbi_pmu.c | 3 ++
> 3 files changed, 73 insertions(+)
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> index 1d85b6617508..9a930afc8f57 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_pmu.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_pmu.h
> @@ -98,6 +98,9 @@ void kvm_riscv_vcpu_pmu_init(struct kvm_vcpu *vcpu);
> int kvm_riscv_vcpu_pmu_snapshot_set_shmem(struct kvm_vcpu *vcpu, unsigned long saddr_low,
> unsigned long saddr_high, unsigned long flags,
> struct kvm_vcpu_sbi_return *retdata);
> +int kvm_riscv_vcpu_pmu_event_info(struct kvm_vcpu *vcpu, unsigned long saddr_low,
> + unsigned long saddr_high, unsigned long num_events,
> + unsigned long flags, struct kvm_vcpu_sbi_return *retdata);
> void kvm_riscv_vcpu_pmu_deinit(struct kvm_vcpu *vcpu);
> void kvm_riscv_vcpu_pmu_reset(struct kvm_vcpu *vcpu);
>
> diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c
> index efd66835c2b8..a30f7ec31479 100644
> --- a/arch/riscv/kvm/vcpu_pmu.c
> +++ b/arch/riscv/kvm/vcpu_pmu.c
> @@ -456,6 +456,73 @@ int kvm_riscv_vcpu_pmu_snapshot_set_shmem(struct kvm_vcpu *vcpu, unsigned long s
> return 0;
> }
>
> +int kvm_riscv_vcpu_pmu_event_info(struct kvm_vcpu *vcpu, unsigned long saddr_low,
> + unsigned long saddr_high, unsigned long num_events,
> + unsigned long flags, struct kvm_vcpu_sbi_return *retdata)
> +{
> + unsigned long hva;
> + struct riscv_pmu_event_info *einfo;
> + int shmem_size = num_events * sizeof(*einfo);
> + bool writable;
> + gpa_t shmem;
> + u32 eidx, etype;
> + u64 econfig;
> + int ret;
> +
> + if (flags != 0 || (saddr_low & (SZ_16 - 1))) {
> + ret = SBI_ERR_INVALID_PARAM;
> + goto out;
> + }
> +
> + shmem = saddr_low;
> + if (saddr_high != 0) {
> + if (IS_ENABLED(CONFIG_32BIT)) {
> + shmem |= ((gpa_t)saddr_high << 32);
> + } else {
> + ret = SBI_ERR_INVALID_ADDRESS;
> + goto out;
> + }
> + }
> +
> + hva = kvm_vcpu_gfn_to_hva_prot(vcpu, shmem >> PAGE_SHIFT, &writable);
> + if (kvm_is_error_hva(hva) || !writable) {
> + ret = SBI_ERR_INVALID_ADDRESS;
This only checks the first page if the address crosses a page boundary. Maybe
that is okay since kvm_vcpu_read_guest()/kvm_vcpu_write_guest() will fail if a
later page is inaccessible?
> + goto out;
> + }
> +
> + einfo = kzalloc(shmem_size, GFP_KERNEL);
> + if (!einfo)
> + return -ENOMEM;
> +
> + ret = kvm_vcpu_read_guest(vcpu, shmem, einfo, shmem_size);
> + if (ret) {
> + ret = SBI_ERR_FAILURE;
> + goto free_mem;
> + }
> +
> + for (int i = 0; i < num_events; i++) {
> + eidx = einfo[i].event_idx;
> + etype = kvm_pmu_get_perf_event_type(eidx);
> + econfig = kvm_pmu_get_perf_event_config(eidx, einfo[i].event_data);
> + ret = riscv_pmu_get_event_info(etype, econfig, NULL);
> + if (ret > 0)
> + einfo[i].output = 1;
This also needs to write `output` in the else case to indicate that the event is
not supported; the spec does not require the caller to initialize bit 0 of
output to zero.
Regards,
Samuel
> + }
> +
> + kvm_vcpu_write_guest(vcpu, shmem, einfo, shmem_size);
> + if (ret) {
> + ret = SBI_ERR_FAILURE;
> + goto free_mem;
> + }
> +
> +free_mem:
> + kfree(einfo);
> +out:
> + retdata->err_val = ret;
> +
> + return 0;
> +}
> +
> int kvm_riscv_vcpu_pmu_num_ctrs(struct kvm_vcpu *vcpu,
> struct kvm_vcpu_sbi_return *retdata)
> {
> diff --git a/arch/riscv/kvm/vcpu_sbi_pmu.c b/arch/riscv/kvm/vcpu_sbi_pmu.c
> index e4be34e03e83..a020d979d179 100644
> --- a/arch/riscv/kvm/vcpu_sbi_pmu.c
> +++ b/arch/riscv/kvm/vcpu_sbi_pmu.c
> @@ -73,6 +73,9 @@ static int kvm_sbi_ext_pmu_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> case SBI_EXT_PMU_SNAPSHOT_SET_SHMEM:
> ret = kvm_riscv_vcpu_pmu_snapshot_set_shmem(vcpu, cp->a0, cp->a1, cp->a2, retdata);
> break;
> + case SBI_EXT_PMU_EVENT_GET_INFO:
> + ret = kvm_riscv_vcpu_pmu_event_info(vcpu, cp->a0, cp->a1, cp->a2, cp->a3, retdata);
> + break;
> default:
> retdata->err_val = SBI_ERR_NOT_SUPPORTED;
> }
>
