RISC-V: KVM: Implement get event info function

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.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Acked-by: Paul Walmsley <pjw@kernel.org>
Link: https://lore.kernel.org/r/20250909-pmu_event_info-v6-7-d8f80cacb884@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>

diff --git a/arch/riscv/include/asm/kvm_vcpu_pmu.h b/arch/riscv/include/asm/kvm_vcpu_pmu.h
index 1d85b6617508845025336e847f3fe4b7198c67ee..9a930afc8f57139945907bf5ab7461447b6a4c71 100644 (file)
--- 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 f8514086bd6b073cbba73416ab29ced80e1b520a..a2fae70ee174c10c27cdcc5e5881cafc89897679 100644 (file)
--- a/arch/riscv/kvm/vcpu_pmu.c
+++ b/arch/riscv/kvm/vcpu_pmu.c
@@ -449,6 +449,65 @@ out:
        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)
+{
+       struct riscv_pmu_event_info *einfo = NULL;
+       int shmem_size = num_events * sizeof(*einfo);
+       gpa_t shmem;
+       u32 eidx, etype;
+       u64 econfig;
+       int ret;
+
+       if (flags != 0 || (saddr_low & (SZ_16 - 1) || num_events == 0)) {
+               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;
+               }
+       }
+
+       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);
+               einfo[i].output = (ret > 0) ? 1 : 0;
+       }
+
+       ret = kvm_vcpu_write_guest(vcpu, shmem, einfo, shmem_size);
+       if (ret) {
+               ret = SBI_ERR_INVALID_ADDRESS;
+               goto free_mem;
+       }
+
+       ret = 0;
+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 e4be34e03e8384503cb83c910e2343647e952473..a020d979d1795a9ce5ac2dab335757b7795bd28e 100644 (file)
--- 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;
        }