Re: [PATCH v3 4/6] kvm powerpc/book3s-apiv2: Introduce kvm-hv specific PMU
From: Athira Rajeev <hidden>
Date: 2025-01-24 18:50:57
Also in:
kvm
quoted hunk ↗ jump to hunk
On 23 Jan 2025, at 5:37 PM, Vaibhav Jain [off-list ref] wrote: Introduce a new PMU named 'kvm-hv' 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 enable users to monitor active kvm-hv based guests. The patch creates necessary scaffolding to for the new PMU callbacks and introduces two new exports kvmppc_{,un}register_pmu() that are called from kvm-hv init and exit function to perform initialize and cleanup for the 'kvm-hv' PMU. The patch doesn't introduce any perf-events yet, which will be introduced in later patches Signed-off-by: Vaibhav Jain <redacted> --- Changelog v2->v3: * Fixed a build warning reported by kernel build robot. Link: https://lore.kernel.org/oe-kbuild-all/202501171030.3x0gqW8G-lkp@intel.com (local) v1->v2: * Fixed an issue of kvm-hv not loading on baremetal kvm [Gautam] --- arch/powerpc/include/asm/kvm_book3s.h | 20 ++++ arch/powerpc/kvm/Makefile | 6 ++ arch/powerpc/kvm/book3s_hv.c | 9 ++ arch/powerpc/kvm/book3s_hv_pmu.c | 133 ++++++++++++++++++++++++++ 4 files changed, 168 insertions(+) create mode 100644 arch/powerpc/kvm/book3s_hv_pmu.cdiff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h index e1ff291ba891..7a7854c65ebb 100644 --- a/arch/powerpc/include/asm/kvm_book3s.h +++ b/arch/powerpc/include/asm/kvm_book3s.h@@ -348,6 +348,26 @@ static inline bool kvmhv_is_nestedv1(void)#endif +/* kvm-ppc pmu registration */ +#if IS_ENABLED(CONFIG_KVM_BOOK3S_64_HV) +#ifdef CONFIG_PERF_EVENTS +int kvmppc_register_pmu(void); +void kvmppc_unregister_pmu(void); + +#else + +static inline int kvmppc_register_pmu(void) +{ + return 0; +} + +static inline void kvmppc_unregister_pmu(void) +{ + /* do nothing */ +} +#endif /* CONFIG_PERF_EVENTS */ +#endif /* CONFIG_KVM_BOOK3S_64_HV */ + int __kvmhv_nestedv2_reload_ptregs(struct kvm_vcpu *vcpu, struct pt_regs *regs); int __kvmhv_nestedv2_mark_dirty_ptregs(struct kvm_vcpu *vcpu, struct pt_regs *regs); int __kvmhv_nestedv2_mark_dirty(struct kvm_vcpu *vcpu, u16 iden);diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile index 4bd9d1230869..7645307ff277 100644 --- a/arch/powerpc/kvm/Makefile +++ b/arch/powerpc/kvm/Makefile@@ -92,6 +92,12 @@ kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \$(kvm-book3s_64-builtin-tm-objs-y) \ $(kvm-book3s_64-builtin-xics-objs-y) +# enable kvm_hv perf events +ifdef CONFIG_PERF_EVENTS +kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HANDLER) += \ + book3s_hv_pmu.o +endif + obj-$(CONFIG_GUEST_STATE_BUFFER_TEST) += test-guest-state-buffer.o endifdiff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 25429905ae90..6365b8126574 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c@@ -6662,6 +6662,14 @@ static int kvmppc_book3s_init_hv(void)return r; } + r = kvmppc_register_pmu(); + if (r == -EOPNOTSUPP) { + pr_info("KVM-HV: PMU not supported %d\n", r); + } else if (r) { + pr_err("KVM-HV: Unable to register PMUs %d\n", r); + goto err; + } + kvm_ops_hv.owner = THIS_MODULE; kvmppc_hv_ops = &kvm_ops_hv;@@ -6676,6 +6684,7 @@ static int kvmppc_book3s_init_hv(void)static void kvmppc_book3s_exit_hv(void) { + kvmppc_unregister_pmu(); kvmppc_uvmem_free(); kvmppc_free_host_rm_ops(); if (kvmppc_radix_possible())diff --git a/arch/powerpc/kvm/book3s_hv_pmu.c b/arch/powerpc/kvm/book3s_hv_pmu.c new file mode 100644 index 000000000000..8c6ed30b7654 --- /dev/null +++ b/arch/powerpc/kvm/book3s_hv_pmu.c@@ -0,0 +1,133 @@ +// 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
Hi Vaibhav All PMU specific code is under “arch/powerpc/perf in the kernel source. Here since we are introducing a kvm-hv specific PMU, can we please have it in arch/powerpc/perf ? Thanks Athira
+
+#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 = {
+ .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,
+};
+
+int kvmppc_register_pmu(void)
+{
+ int rc = -EOPNOTSUPP;
+
+ /* only support events for nestedv2 right now */
+ if (kvmhv_is_nestedv2()) {
+ /* Setup done now register the PMU */
+ pr_info("Registering kvm-hv pmu");
+
+ /* Register only if we arent already registered */
+ rc = (kvmppc_pmu.type == -1) ?
+ perf_pmu_register(&kvmppc_pmu, kvmppc_pmu.name,
+ -1) : 0;
+ }
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(kvmppc_register_pmu);
+
+void kvmppc_unregister_pmu(void)
+{
+ if (kvmhv_is_nestedv2()) {
+ if (kvmppc_pmu.type != -1)
+ perf_pmu_unregister(&kvmppc_pmu);
+
+ pr_info("kvmhv_pmu unregistered.\n");
+ }
+}
+EXPORT_SYMBOL_GPL(kvmppc_unregister_pmu);
--
2.48.1