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[23.128.96.18]) by mx.google.com with ESMTP id lg10si29452571ejb.120.2021.01.04.05.27.30; Mon, 04 Jan 2021 05:27:53 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727176AbhADNZJ (ORCPT + 99 others); Mon, 4 Jan 2021 08:25:09 -0500 Received: from mga07.intel.com ([134.134.136.100]:23246 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726502AbhADNZI (ORCPT ); Mon, 4 Jan 2021 08:25:08 -0500 IronPort-SDR: MJ2GCXb2/8ShcWClvkKUweoyFOaGV3xFZEbY03xHPMdXokvGVCvsbucWcv+YfkeX3ojghhNUet xER6HYivHlvQ== X-IronPort-AV: E=McAfee;i="6000,8403,9853"; a="241034316" X-IronPort-AV: E=Sophos;i="5.78,474,1599548400"; d="scan'208";a="241034316" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Jan 2021 05:22:12 -0800 IronPort-SDR: wJ1Uqk9JEYlvUZTTzHukE3gWww3UgbyKka/qbz8lmWUVRQ0Gvro6zCdm0uZ9WIMu6nMw+AjmWy 2AN5Rluwa6TQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.78,474,1599548400"; d="scan'208";a="461944553" Received: from clx-ap-likexu.sh.intel.com ([10.239.48.108]) by fmsmga001.fm.intel.com with ESMTP; 04 Jan 2021 05:22:09 -0800 From: Like Xu To: Peter Zijlstra , Paolo Bonzini , eranian@google.com, kvm@vger.kernel.org Cc: Ingo Molnar , Sean Christopherson , Thomas Gleixner , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Andi Kleen , Kan Liang , wei.w.wang@intel.com, luwei.kang@intel.com, linux-kernel@vger.kernel.org Subject: [PATCH v3 04/17] perf: x86/ds: Handle guest PEBS overflow PMI and inject it to guest Date: Mon, 4 Jan 2021 21:15:29 +0800 Message-Id: <20210104131542.495413-5-like.xu@linux.intel.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210104131542.495413-1-like.xu@linux.intel.com> References: <20210104131542.495413-1-like.xu@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With PEBS virtualization, the PEBS records get delivered to the guest, and host still sees the PEBS overflow PMI from guest PEBS counters. This would normally result in a spurious host PMI and we needs to inject that PEBS overflow PMI into the guest, so that the guest PMI handler can handle the PEBS records. Check for this case in the host perf PEBS handler. If a PEBS overflow PMI occurs and it's not generated from host side (via check host DS), a fake event will be triggered. The fake event causes the KVM PMI callback to be called, thereby injecting the PEBS overflow PMI into the guest. No matter how many guest PEBS counters are overflowed, only triggering one fake event is enough. The guest PEBS handler would retrieve the correct information from its own PEBS records buffer. A guest PEBS overflow PMI would be missed when a PEBS counter is enabled on the host side and coincidentally a host PEBS overflow PMI based on host DS_AREA is also triggered right after vm-exit due to the guest PEBS overflow PMI based on guest DS_AREA. In that case, KVM will disable guest PEBS before vm-entry once there's a host PEBS counter enabled on the same CPU. Originally-by: Andi Kleen Co-developed-by: Kan Liang Signed-off-by: Kan Liang Signed-off-by: Like Xu --- arch/x86/events/intel/ds.c | 62 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 62 insertions(+) diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c index b47cc4226934..c499bdb58373 100644 --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -1721,6 +1721,65 @@ intel_pmu_save_and_restart_reload(struct perf_event *event, int count) return 0; } +/* + * We may be running with guest PEBS events created by KVM, and the + * PEBS records are logged into the guest's DS and invisible to host. + * + * In the case of guest PEBS overflow, we only trigger a fake event + * to emulate the PEBS overflow PMI for guest PBES counters in KVM. + * The guest will then vm-entry and check the guest DS area to read + * the guest PEBS records. + * + * The guest PEBS overflow PMI may be dropped when both the guest and + * the host use PEBS. Therefore, KVM will not enable guest PEBS once + * the host PEBS is enabled since it may bring a confused unknown NMI. + * + * The contents and other behavior of the guest event do not matter. + */ +static int intel_pmu_handle_guest_pebs(struct cpu_hw_events *cpuc, + struct pt_regs *iregs, + struct debug_store *ds) +{ + struct perf_sample_data data; + struct perf_event *event = NULL; + u64 guest_pebs_idxs = cpuc->pebs_enabled & ~cpuc->intel_ctrl_host_mask; + int bit; + + /* + * Ideally, we should check guest DS to understand if it's + * a guest PEBS overflow PMI from guest PEBS counters. + * However, it brings high overhead to retrieve guest DS in host. + * So we check host DS instead for performance. + * + * If PEBS interrupt threshold on host is not exceeded in a NMI, there + * must be a PEBS overflow PMI generated from the guest PEBS counters. + * There is no ambiguity since the reported event in the PMI is guest + * only. It gets handled correctly on a case by case base for each event. + * + * Note: KVM disables the co-existence of guest PEBS and host PEBS. + */ + if (!guest_pebs_idxs || !in_nmi() || + ds->pebs_index >= ds->pebs_interrupt_threshold) + return 0; + + for_each_set_bit(bit, (unsigned long *)&guest_pebs_idxs, + INTEL_PMC_IDX_FIXED + x86_pmu.num_counters_fixed) { + + event = cpuc->events[bit]; + if (!event->attr.precise_ip) + continue; + + perf_sample_data_init(&data, 0, event->hw.last_period); + if (perf_event_overflow(event, &data, iregs)) + x86_pmu_stop(event, 0); + + /* Inject one fake event is enough. */ + return 1; + } + + return 0; +} + static __always_inline void __intel_pmu_pebs_event(struct perf_event *event, struct pt_regs *iregs, @@ -1965,6 +2024,9 @@ static void intel_pmu_drain_pebs_icl(struct pt_regs *iregs, struct perf_sample_d if (!x86_pmu.pebs_active) return; + if (intel_pmu_handle_guest_pebs(cpuc, iregs, ds)) + return; + base = (struct pebs_basic *)(unsigned long)ds->pebs_buffer_base; top = (struct pebs_basic *)(unsigned long)ds->pebs_index; -- 2.29.2