From 2721e8da2de7271533ac36285332219f700d16ca Mon Sep 17 00:00:00 2001 From: Dapeng Mi Date: Wed, 29 Oct 2025 18:21:33 +0800 Subject: [PATCH] perf/x86/intel: Allocate arch-PEBS buffer and initialize PEBS_BASE MSR Arch-PEBS introduces a new MSR IA32_PEBS_BASE to store the arch-PEBS buffer physical address. This patch allocates arch-PEBS buffer and then initialize IA32_PEBS_BASE MSR with the buffer physical address. Co-developed-by: Kan Liang Signed-off-by: Kan Liang Signed-off-by: Dapeng Mi Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20251029102136.61364-10-dapeng1.mi@linux.intel.com --- arch/x86/events/intel/core.c | 11 ++++- arch/x86/events/intel/ds.c | 82 ++++++++++++++++++++++++++++----- arch/x86/events/perf_event.h | 11 ++++- arch/x86/include/asm/intel_ds.h | 3 +- 4 files changed, 92 insertions(+), 15 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index de4dbde28adcd..6e04d73dfae50 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -5227,7 +5227,13 @@ err: static int intel_pmu_cpu_prepare(int cpu) { - return intel_cpuc_prepare(&per_cpu(cpu_hw_events, cpu), cpu); + int ret; + + ret = intel_cpuc_prepare(&per_cpu(cpu_hw_events, cpu), cpu); + if (ret) + return ret; + + return alloc_arch_pebs_buf_on_cpu(cpu); } static void flip_smm_bit(void *data) @@ -5458,6 +5464,7 @@ static void intel_pmu_cpu_starting(int cpu) return; init_debug_store_on_cpu(cpu); + init_arch_pebs_on_cpu(cpu); /* * Deal with CPUs that don't clear their LBRs on power-up, and that may * even boot with LBRs enabled. @@ -5555,6 +5562,7 @@ static void free_excl_cntrs(struct cpu_hw_events *cpuc) static void intel_pmu_cpu_dying(int cpu) { fini_debug_store_on_cpu(cpu); + fini_arch_pebs_on_cpu(cpu); } void intel_cpuc_finish(struct cpu_hw_events *cpuc) @@ -5575,6 +5583,7 @@ static void intel_pmu_cpu_dead(int cpu) { struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu); + release_arch_pebs_buf_on_cpu(cpu); intel_cpuc_finish(cpuc); if (is_hybrid() && cpuc->pmu) diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index fe1bf373409e2..5c26a5235f94c 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -625,13 +625,18 @@ static int alloc_pebs_buffer(int cpu) int max, node = cpu_to_node(cpu); void *buffer, *insn_buff, *cea; - if (!x86_pmu.ds_pebs) + if (!intel_pmu_has_pebs()) return 0; buffer = dsalloc_pages(bsiz, GFP_KERNEL, cpu); if (unlikely(!buffer)) return -ENOMEM; + if (x86_pmu.arch_pebs) { + hwev->pebs_vaddr = buffer; + return 0; + } + /* * HSW+ already provides us the eventing ip; no need to allocate this * buffer then. @@ -644,7 +649,7 @@ static int alloc_pebs_buffer(int cpu) } per_cpu(insn_buffer, cpu) = insn_buff; } - hwev->ds_pebs_vaddr = buffer; + hwev->pebs_vaddr = buffer; /* Update the cpu entry area mapping */ cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.pebs_buffer; ds->pebs_buffer_base = (unsigned long) cea; @@ -660,17 +665,20 @@ static void release_pebs_buffer(int cpu) struct cpu_hw_events *hwev = per_cpu_ptr(&cpu_hw_events, cpu); void *cea; - if (!x86_pmu.ds_pebs) + if (!intel_pmu_has_pebs()) return; - kfree(per_cpu(insn_buffer, cpu)); - per_cpu(insn_buffer, cpu) = NULL; + if (x86_pmu.ds_pebs) { + kfree(per_cpu(insn_buffer, cpu)); + per_cpu(insn_buffer, cpu) = NULL; - /* Clear the fixmap */ - cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.pebs_buffer; - ds_clear_cea(cea, x86_pmu.pebs_buffer_size); - dsfree_pages(hwev->ds_pebs_vaddr, x86_pmu.pebs_buffer_size); - hwev->ds_pebs_vaddr = NULL; + /* Clear the fixmap */ + cea = &get_cpu_entry_area(cpu)->cpu_debug_buffers.pebs_buffer; + ds_clear_cea(cea, x86_pmu.pebs_buffer_size); + } + + dsfree_pages(hwev->pebs_vaddr, x86_pmu.pebs_buffer_size); + hwev->pebs_vaddr = NULL; } static int alloc_bts_buffer(int cpu) @@ -823,6 +831,56 @@ void reserve_ds_buffers(void) } } +inline int alloc_arch_pebs_buf_on_cpu(int cpu) +{ + if (!x86_pmu.arch_pebs) + return 0; + + return alloc_pebs_buffer(cpu); +} + +inline void release_arch_pebs_buf_on_cpu(int cpu) +{ + if (!x86_pmu.arch_pebs) + return; + + release_pebs_buffer(cpu); +} + +void init_arch_pebs_on_cpu(int cpu) +{ + struct cpu_hw_events *cpuc = per_cpu_ptr(&cpu_hw_events, cpu); + u64 arch_pebs_base; + + if (!x86_pmu.arch_pebs) + return; + + if (!cpuc->pebs_vaddr) { + WARN(1, "Fail to allocate PEBS buffer on CPU %d\n", cpu); + x86_pmu.pebs_active = 0; + return; + } + + /* + * 4KB-aligned pointer of the output buffer + * (__alloc_pages_node() return page aligned address) + * Buffer Size = 4KB * 2^SIZE + * contiguous physical buffer (__alloc_pages_node() with order) + */ + arch_pebs_base = virt_to_phys(cpuc->pebs_vaddr) | PEBS_BUFFER_SHIFT; + wrmsr_on_cpu(cpu, MSR_IA32_PEBS_BASE, (u32)arch_pebs_base, + (u32)(arch_pebs_base >> 32)); + x86_pmu.pebs_active = 1; +} + +inline void fini_arch_pebs_on_cpu(int cpu) +{ + if (!x86_pmu.arch_pebs) + return; + + wrmsr_on_cpu(cpu, MSR_IA32_PEBS_BASE, 0, 0); +} + /* * BTS */ @@ -2883,8 +2941,8 @@ static void intel_pmu_drain_arch_pebs(struct pt_regs *iregs, return; } - base = cpuc->ds_pebs_vaddr; - top = (void *)((u64)cpuc->ds_pebs_vaddr + + base = cpuc->pebs_vaddr; + top = (void *)((u64)cpuc->pebs_vaddr + (index.wr << ARCH_PEBS_INDEX_WR_SHIFT)); index.wr = 0; diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index ca5289980b527..13f411bca6bc5 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -283,8 +283,9 @@ struct cpu_hw_events { * Intel DebugStore bits */ struct debug_store *ds; - void *ds_pebs_vaddr; void *ds_bts_vaddr; + /* DS based PEBS or arch-PEBS buffer address */ + void *pebs_vaddr; u64 pebs_enabled; int n_pebs; int n_large_pebs; @@ -1617,6 +1618,14 @@ extern void intel_cpuc_finish(struct cpu_hw_events *cpuc); int intel_pmu_init(void); +int alloc_arch_pebs_buf_on_cpu(int cpu); + +void release_arch_pebs_buf_on_cpu(int cpu); + +void init_arch_pebs_on_cpu(int cpu); + +void fini_arch_pebs_on_cpu(int cpu); + void init_debug_store_on_cpu(int cpu); void fini_debug_store_on_cpu(int cpu); diff --git a/arch/x86/include/asm/intel_ds.h b/arch/x86/include/asm/intel_ds.h index 5dbeac48a5b93..023c2883f9f3e 100644 --- a/arch/x86/include/asm/intel_ds.h +++ b/arch/x86/include/asm/intel_ds.h @@ -4,7 +4,8 @@ #include #define BTS_BUFFER_SIZE (PAGE_SIZE << 4) -#define PEBS_BUFFER_SIZE (PAGE_SIZE << 4) +#define PEBS_BUFFER_SHIFT 4 +#define PEBS_BUFFER_SIZE (PAGE_SIZE << PEBS_BUFFER_SHIFT) /* The maximal number of PEBS events: */ #define MAX_PEBS_EVENTS_FMT4 8 -- 2.47.3