Re: [PATCH v5 08/14] RISC-V: KVM: Add SBI PMU extension support

[Atish Patra]

On Sun, Feb 5, 2023 at 2:31 AM Conor Dooley <conor@xxxxxxxxxx> wrote:
>
>
>
> On 5 February 2023 02:15:09 GMT+01:00, Atish Patra <atishp@xxxxxxxxxxxx> wrote:
> >SBI PMU extension allows KVM guests to configure/start/stop/query about
> >the PMU counters in virtualized enviornment as well.
> >
> >In order to allow that, KVM implements the entire SBI PMU extension.
> >
> >Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
> >Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
>
> Hey Atish,
> CI is still complaining about something in this patch:
> https://gist.github.com/conor-pwbot/8f8d6a60a65b0b44d96c9c3b220e3efd
>

This is an invalid warning as vcpu_sbi_ext_pmu is used as an extern variable in
arch/riscv/kvm/vcpu_sbi.c. That's how every sbi extension code defines the
kvm_vcpu_sbi_extension in its own respective file.


> I'm without a laptop this weekend, so apologies for
> the lack of investigation as to whether there's a
> reason for it.
>
> Cheers,
> Conor.
>
>
> >---
> > arch/riscv/kvm/Makefile       |  2 +-
> > arch/riscv/kvm/vcpu_sbi.c     | 11 +++++
> > arch/riscv/kvm/vcpu_sbi_pmu.c | 87 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 99 insertions(+), 1 deletion(-)
> > create mode 100644 arch/riscv/kvm/vcpu_sbi_pmu.c
> >was > >diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
> >index 5de1053..278e97c 100644
> >--- a/arch/riscv/kvm/Makefile
> >+++ b/arch/riscv/kvm/Makefile
> >@@ -25,4 +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-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o
> >+kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o vcpu_sbi_pmu.o
> >diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> >index fe2897e..15fde15 100644
> >--- a/arch/riscv/kvm/vcpu_sbi.c
> >+++ b/arch/riscv/kvm/vcpu_sbi.c
> >@@ -20,6 +20,16 @@ static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01 = {
> > };
> > #endif
> >
> >+#ifdef CONFIG_RISCV_PMU_SBI
> >+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu;
> >+#else
> >+static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu = {
> >+      .extid_start = -1UL,
> >+      .extid_end = -1UL,
> >+      .handler = NULL,
> >+};
> >+#endif
> >+
> > static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
> >       &vcpu_sbi_ext_v01
> >       &vcpu_sbi_ext_base,
> >@@ -28,6 +38,7 @@ static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
> >       &vcpu_sbi_ext_rfence,
> >       &vcpu_sbi_ext_srst,
> >       &vcpu_sbi_ext_hsm,
> >+      &vcpu_sbi_ext_pmu,
> >       &vcpu_sbi_ext_experimental,
> >       &vcpu_sbi_ext_vendor,
> > };
> >diff --git a/arch/riscv/kvm/vcpu_sbi_pmu.c b/arch/riscv/kvm/vcpu_sbi_pmu.c
> >new file mode 100644
> >index 0000000..9fdc1e1
> >--- /dev/null
> >+++ b/arch/riscv/kvm/vcpu_sbi_pmu.c
> >@@ -0,0 +1,87 @@
> >+// 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 <asm/csr.h>
> >+#include <asm/sbi.h>
> >+#include <asm/kvm_vcpu_sbi.h>
> >+
> >+static int kvm_sbi_ext_pmu_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
> >+                                 struct kvm_vcpu_sbi_return *retdata)
> >+{
> >+      int ret = 0;
> >+      struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
> >+      struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> >+      unsigned long funcid = cp->a6;
> >+      u64 temp;
> >+
> >+      /* Return not supported if PMU is not initialized */
> >+      if (!kvpmu->init_done) {
> >+              retdata->err_val = SBI_ERR_NOT_SUPPORTED;
> >+              return 0;
> >+      }
> >+
> >+      switch (funcid) {
> >+      case SBI_EXT_PMU_NUM_COUNTERS:
> >+              ret = kvm_riscv_vcpu_pmu_num_ctrs(vcpu, retdata);
> >+              break;
> >+      case SBI_EXT_PMU_COUNTER_GET_INFO:
> >+              ret = kvm_riscv_vcpu_pmu_ctr_info(vcpu, cp->a0, retdata);
> >+              break;
> >+      case SBI_EXT_PMU_COUNTER_CFG_MATCH:
> >+#if defined(CONFIG_32BIT)
> >+              temp = ((uint64_t)cp->a5 << 32) | cp->a4;
> >+#else
> >+              temp = cp->a4;
> >+#endif
> >+              /*
> >+               * This can fail if perf core framework fails to create an event.
> >+               * Forward the error to userspace because it's an error happened
> >+               * within the host kernel. The other option would be to convert
> >+               * this an SBI error and forward to the guest.
> >+               */
> >+              ret = kvm_riscv_vcpu_pmu_ctr_cfg_match(vcpu, cp->a0, cp->a1,
> >+                                                     cp->a2, cp->a3, temp, retdata);
> >+              break;
> >+      case SBI_EXT_PMU_COUNTER_START:
> >+#if defined(CONFIG_32BIT)
> >+              temp = ((uint64_t)cp->a4 << 32) | cp->a3;
> >+#else
> >+              temp = cp->a3;
> >+#endif
> >+              ret = kvm_riscv_vcpu_pmu_ctr_start(vcpu, cp->a0, cp->a1, cp->a2,
> >+                                                 temp, retdata);
> >+              break;
> >+      case SBI_EXT_PMU_COUNTER_STOP:
> >+              ret = kvm_riscv_vcpu_pmu_ctr_stop(vcpu, cp->a0, cp->a1, cp->a2, retdata);
> >+              break;
> >+      case SBI_EXT_PMU_COUNTER_FW_READ:
> >+              ret = kvm_riscv_vcpu_pmu_ctr_read(vcpu, cp->a0, retdata);
> >+              break;
> >+      default:
> >+              retdata->err_val = SBI_ERR_NOT_SUPPORTED;
> >+      }
> >+
> >+      return ret;
> >+}
> >+
> >+static unsigned long kvm_sbi_ext_pmu_probe(struct kvm_vcpu *vcpu)
> >+{
> >+      struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu);
> >+
> >+      return kvpmu->init_done;
> >+}
> >+
> >+const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pmu = {
> >+      .extid_start = SBI_EXT_PMU,
> >+      .extid_end = SBI_EXT_PMU,
> >+      .handler = kvm_sbi_ext_pmu_handler,
> >+      .probe = kvm_sbi_ext_pmu_probe,
> >+};



-- 
Regards,
Atish