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

From: Conor Dooley
Date: Tue Feb 07 2023 - 01:25:05 EST



On 7 February 2023 06:10:57 GMT, Atish Patra <atishp@xxxxxxxxxxxxxx> wrote:
>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.

Ah, so the user is in another patch.

>> I'm without a laptop this weekend, so apologies for
>> the lack of investigation as to whether there's a
>> reason for it.

Hard to check these things from a phone!
Sorry for bothering you so.

>>
>> 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,
>> >+};
>
>
>