Athira Rajeev <atrajeev@xxxxxxxxxxxxx> writes: >> On 24 Feb 2025, at 6:45 PM, Vaibhav Jain <vaibhav@xxxxxxxxxxxxx> wrote: >> >> Introduce a new PMU named 'kvm-hv' inside a new module named 'kvm-hv-pmu' >> to report Book3s kvm-hv specific performance counters. This will expose >> KVM-HV specific performance attributes to user-space via kernel's PMU >> infrastructure and would enableusers to monitor active kvm-hv based guests. >> >> The patch creates necessary scaffolding to for the new PMU callbacks and >> introduces the new kernel module name 'kvm-hv-pmu' which is built with >> CONFIG_KVM_BOOK3S_HV_PMU. The patch doesn't introduce any perf-events yet, >> which will be introduced in later patches >> >> Signed-off-by: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx> >> >> --- >> Changelog >> >> v3->v4: >> * Introduced a new kernel module named 'kmv-hv-pmu' to host the new PMU >> instead of building the as part of KVM-HV module. [ Maddy ] >> * Moved the code from arch/powerpc/kvm to arch/powerpc/perf [ Atheera ] >> * Added a new config named KVM_BOOK3S_HV_PMU to arch/powerpc/kvm/Kconfig >> >> v2->v3: >> * Fixed a build warning reported by kernel build robot. >> Link: >> https://lore.kernel.org/oe-kbuild-all/202501171030.3x0gqW8G-lkp@xxxxxxxxx >> >> v1->v2: >> * Fixed an issue of kvm-hv not loading on baremetal kvm [Gautam] >> --- >> arch/powerpc/kvm/Kconfig | 13 ++++ >> arch/powerpc/perf/Makefile | 2 + >> arch/powerpc/perf/kvm-hv-pmu.c | 138 +++++++++++++++++++++++++++++++++ >> 3 files changed, 153 insertions(+) >> create mode 100644 arch/powerpc/perf/kvm-hv-pmu.c >> >> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig >> index dbfdc126bf14..5f0ce19e7e27 100644 >> --- a/arch/powerpc/kvm/Kconfig >> +++ b/arch/powerpc/kvm/Kconfig >> @@ -83,6 +83,7 @@ config KVM_BOOK3S_64_HV >> depends on KVM_BOOK3S_64 && PPC_POWERNV >> select KVM_BOOK3S_HV_POSSIBLE >> select KVM_GENERIC_MMU_NOTIFIER >> + select KVM_BOOK3S_HV_PMU >> select CMA >> help >> Support running unmodified book3s_64 guest kernels in >> @@ -171,6 +172,18 @@ config KVM_BOOK3S_HV_NESTED_PMU_WORKAROUND >> those buggy L1s which saves the L2 state, at the cost of performance >> in all nested-capable guest entry/exit. >> >> +config KVM_BOOK3S_HV_PMU >> + tristate "Hypervisor Perf events for KVM Book3s-HV" >> + depends on KVM_BOOK3S_64_HV && HV_PERF_CTRS >> + help >> + Enable Book3s-HV Hypervisor Perf events PMU named 'kvm-hv'. These >> + Perf events give an overview of hypervisor performance overall >> + instead of a specific guests. Currently the PMU reports >> + L0-Hypervisor stats on a kvm-hv enabled PSeries LPAR like: >> + * Total/Used Guest-Heap >> + * Total/Used Guest Page-table Memory >> + * Total amount of Guest Page-table Memory reclaimed >> + >> config KVM_BOOKE_HV >> bool >> >> diff --git a/arch/powerpc/perf/Makefile b/arch/powerpc/perf/Makefile >> index ac2cf58d62db..7f53fcb7495a 100644 >> --- a/arch/powerpc/perf/Makefile >> +++ b/arch/powerpc/perf/Makefile >> @@ -18,6 +18,8 @@ obj-$(CONFIG_HV_PERF_CTRS) += hv-24x7.o hv-gpci.o hv-common.o >> >> obj-$(CONFIG_VPA_PMU) += vpa-pmu.o >> >> +obj-$(CONFIG_KVM_BOOK3S_HV_PMU) += kvm-hv-pmu.o >> + >> obj-$(CONFIG_PPC_8xx) += 8xx-pmu.o >> >> obj-$(CONFIG_PPC64) += $(obj64-y) >> diff --git a/arch/powerpc/perf/kvm-hv-pmu.c b/arch/powerpc/perf/kvm-hv-pmu.c >> new file mode 100644 >> index 000000000000..c154f54e09e2 >> --- /dev/null >> +++ b/arch/powerpc/perf/kvm-hv-pmu.c >> @@ -0,0 +1,138 @@ >> +// SPDX-License-Identifier: GPL-2.0 >> +/* >> + * Description: PMUs specific to running nested KVM-HV guests >> + * on Book3S processors (specifically POWER9 and later). >> + */ >> + >> +#define pr_fmt(fmt) "kvmppc-pmu: " fmt >> + >> +#include "asm-generic/local64.h" >> +#include <linux/kernel.h> >> +#include <linux/errno.h> >> +#include <linux/ratelimit.h> >> +#include <linux/kvm_host.h> >> +#include <linux/gfp_types.h> >> +#include <linux/pgtable.h> >> +#include <linux/perf_event.h> >> +#include <linux/spinlock_types.h> >> +#include <linux/spinlock.h> >> + >> +#include <asm/types.h> >> +#include <asm/kvm_ppc.h> >> +#include <asm/kvm_book3s.h> >> +#include <asm/mmu.h> >> +#include <asm/pgalloc.h> >> +#include <asm/pte-walk.h> >> +#include <asm/reg.h> >> +#include <asm/plpar_wrappers.h> >> +#include <asm/firmware.h> >> + >> +enum kvmppc_pmu_eventid { >> + KVMPPC_EVENT_MAX, >> +}; >> + >> +static struct attribute *kvmppc_pmu_events_attr[] = { >> + NULL, >> +}; >> + >> +static const struct attribute_group kvmppc_pmu_events_group = { >> + .name = "events", >> + .attrs = kvmppc_pmu_events_attr, >> +}; >> + >> +PMU_FORMAT_ATTR(event, "config:0"); >> +static struct attribute *kvmppc_pmu_format_attr[] = { >> + &format_attr_event.attr, >> + NULL, >> +}; >> + >> +static struct attribute_group kvmppc_pmu_format_group = { >> + .name = "format", >> + .attrs = kvmppc_pmu_format_attr, >> +}; >> + >> +static const struct attribute_group *kvmppc_pmu_attr_groups[] = { >> + &kvmppc_pmu_events_group, >> + &kvmppc_pmu_format_group, >> + NULL, >> +}; >> + >> +static int kvmppc_pmu_event_init(struct perf_event *event) >> +{ >> + unsigned int config = event->attr.config; >> + >> + pr_debug("%s: Event(%p) id=%llu cpu=%x on_cpu=%x config=%u", >> + __func__, event, event->id, event->cpu, >> + event->oncpu, config); >> + >> + if (event->attr.type != event->pmu->type) >> + return -ENOENT; >> + >> + if (config >= KVMPPC_EVENT_MAX) >> + return -EINVAL; >> + >> + local64_set(&event->hw.prev_count, 0); >> + local64_set(&event->count, 0); >> + >> + return 0; >> +} >> + >> +static void kvmppc_pmu_del(struct perf_event *event, int flags) >> +{ >> +} >> + >> +static int kvmppc_pmu_add(struct perf_event *event, int flags) >> +{ >> + return 0; >> +} >> + >> +static void kvmppc_pmu_read(struct perf_event *event) >> +{ >> +} >> + >> +/* L1 wide counters PMU */ >> +static struct pmu kvmppc_pmu = { >> + .module = THIS_MODULE, >> + .task_ctx_nr = perf_sw_context, >> + .name = "kvm-hv", >> + .event_init = kvmppc_pmu_event_init, >> + .add = kvmppc_pmu_add, >> + .del = kvmppc_pmu_del, >> + .read = kvmppc_pmu_read, >> + .attr_groups = kvmppc_pmu_attr_groups, >> + .type = -1, >> +}; >> + >> +static int __init kvmppc_register_pmu(void) >> +{ >> + int rc = -EOPNOTSUPP; >> + >> + /* only support events for nestedv2 right now */ >> + if (kvmhv_is_nestedv2()) { > > We don’t need PVR check here ? Description of module says this is > supported for power9 and later. The hcalls this module depends on, are only available to LPAR/KVM-Guest running with api-v2 support hence this is needed. >> + /* Setup done now register the PMU */ >> + pr_info("Registering kvm-hv pmu"); >> + >> + /* Register only if we arent already registered */ > Not sure why we need this… Have you seen any issue without this ? I don’t see any similar check in arch/powerpc/perf/vpa-pmu.c , > This check is taken from the previous version of this patch which prevented struct pmu initialization multiple times. However with now a seperate module this check is probably not needed. >> + rc = (kvmppc_pmu.type == -1) ? >> + perf_pmu_register(&kvmppc_pmu, kvmppc_pmu.name, >> + -1) : 0; >> + } >> + >> + return rc; >> +} >> + >> +static void __exit kvmppc_unregister_pmu(void) >> +{ >> + if (kvmhv_is_nestedv2()) { >> + if (kvmppc_pmu.type != -1) >> + perf_pmu_unregister(&kvmppc_pmu); >> + >> + pr_info("kvmhv_pmu unregistered.\n"); >> + } >> +} >> + >> +module_init(kvmppc_register_pmu); >> +module_exit(kvmppc_unregister_pmu); >> +MODULE_DESCRIPTION("KVM PPC Book3s-hv PMU"); >> +MODULE_AUTHOR("Vaibhav Jain <vaibhav@xxxxxxxxxxxxx>"); >> +MODULE_LICENSE("GPL"); >> -- >> 2.48.1 >> >> >> > -- Cheers ~ Vaibhav
