From patchwork Wed Jul 10 04:51:12 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhao Liu X-Patchwork-Id: 13728876 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E4342C3DA41 for ; Wed, 10 Jul 2024 04:37:52 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sRP3s-0005fe-SO; Wed, 10 Jul 2024 00:36:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sRP3q-0005cf-SX; Wed, 10 Jul 2024 00:36:10 -0400 Received: from mgamail.intel.com ([198.175.65.11]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sRP3n-0006sb-BR; Wed, 10 Jul 2024 00:36:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1720586167; x=1752122167; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=PibKnXq9Pq/c31n0bxDbMaIs/xxPngjdmk6sa7uOb+M=; b=PNR8O2C+RRsR0rGfo1/PTbXkEbki8HKZS0F8kXaK42MVvFJGTZVo08A8 roTknVBtK/djTSB7N5SrqYtv4l/Kz0GjbUo6GBma+QtGxC4g10tsuokPV NyEehUKFfNt6meXP5trGqkcB4TGvB1/rbQtQY5ZEXyaDej40doCnl9ZBn laItybsiqOwluuA7FnzMP+KKLDviQdpqut0h/q26etv7Tzlj4rTC2KKri LpGgXXdmcLxWtz2iMsvo2uNENXj1MZacgqaaQOPRSjFXXkB8DSpfMZNvI ZG6zpYqM5o2xBWZetOEF1koloMeEb05MwIBrzj+47wtHkO0kvruoRjM5D g==; X-CSE-ConnectionGUID: XjmujolvREKUrI/PnxFGRw== X-CSE-MsgGUID: eAblcny/Rtm+9inTddTCiw== X-IronPort-AV: E=McAfee;i="6700,10204,11128"; a="28473753" X-IronPort-AV: E=Sophos;i="6.09,197,1716274800"; d="scan'208";a="28473753" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Jul 2024 21:35:56 -0700 X-CSE-ConnectionGUID: xL+EWwXbRIeKbL4iBoT2oQ== X-CSE-MsgGUID: SL/LYDmCRTOQF7RGGpwW5g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.09,197,1716274800"; d="scan'208";a="79238097" Received: from liuzhao-optiplex-7080.sh.intel.com ([10.239.160.36]) by fmviesa001.fm.intel.com with ESMTP; 09 Jul 2024 21:35:51 -0700 From: Zhao Liu To: Paolo Bonzini , Eric Blake , Markus Armbruster , Michael Roth , =?utf-8?q?Daniel_P_=2E_Berrang=C3=A9?= , Eduardo Habkost , Marcelo Tosatti , Shaoqin Huang , Eric Auger , Peter Maydell , Laurent Vivier , Thomas Huth , Sebastian Ott , Gavin Shan Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, qemu-arm@nongnu.org, Zhenyu Wang , Dapeng Mi , Yuan Yao , Xiong Zhang , Mingwei Zhang , Jim Mattson , Zhao Liu Subject: [RFC 0/5] accel/kvm: Support KVM PMU filter Date: Wed, 10 Jul 2024 12:51:12 +0800 Message-Id: <20240710045117.3164577-1-zhao1.liu@intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Received-SPF: pass client-ip=198.175.65.11; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -44 X-Spam_score: -4.5 X-Spam_bar: ---- X-Spam_report: (-4.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.144, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi QEMU maintainers, arm and PMU folks, I picked up Shaoqing's previous work [1] on the KVM PMU filter for arm, and now is trying to support this feature for x86 with a JSON-compatible API. While arm and x86 use different KVM ioctls to configure the PMU filter, considering they all have similar inputs (PMU event + action), it is still possible to abstract a generic, cross-architecture kvm-pmu-filter object and provide users with a sufficiently generic or near-consistent QAPI interface. That's what I did in this series, a new kvm-pmu-filter object, with the API like: -object '{"qom-type":"kvm-pmu-filter","id":"f0","events":[{"action":"allow","format":"raw","code":"0xc4"}]}' For i386, this object is inserted into kvm accelerator and is extended to support fixed-counter and more formats ("x86-default" and "x86-masked-entry"): -accel kvm,pmu-filter=f0 \ -object pmu='{"qom-type":"kvm-pmu-filter","id":"f0","x86-fixed-counter":{"action":"allow","bitmap":"0x0"},"events":[{"action":"allow","format":"x86-masked-entry","select":"0xc4","mask":"0xff","match":"0","exclude":true},{"action":"allow","format":"x86-masked-entry","select":"0xc5","mask":"0xff","match":"0","exclude":true}]}' This object can still be added as the property to the arch CPU if it is desired as a per CPU feature (as Shaoqin did for arm before). Welcome your feedback and comments! Introduction ============ Formats supported in kvm-pmu-filter ----------------------------------- This series supports 3 formats: * raw format (general format). This format indicates the code that has been encoded to be able to index the PMU events, and which can be delivered directly to the KVM ioctl. For arm, this means the event code, and for i386, this means the raw event with the layout like: select high bit | umask | select low bits * x86-default format (i386 specific) x86 commonly uses select&umask to identify PMU events, and this format is used to support the select&umask. Then QEMU will encode select and umask into a raw format code. * x86-masked-entry (i386 specific) This is a special format that x86's KVM_SET_PMU_EVENT_FILTER supports. Hexadecimal value string ------------------------ In practice, the values associated with PMU events (code for arm, select& umask for x86) are often expressed in hexadecimal. Further, from linux perf related information (tools/perf/pmu-events/arch/*/*/*.json), x86/ arm64/riscv/nds32/powerpc all prefer the hexadecimal numbers and only s390 uses decimal value. Therefore, it is necessary to support hexadecimal in order to honor PMU conventions. However, unfortunately, standard JSON (RFC 8259) does not support hexadecimal numbers. So I can only consider using the numeric string in the QAPI and then parsing it to a number. To achieve this, I defined two versions of PMU-related structures in kvm.json: * a native version that accepts numeric values, which is used for QEMU's internal code processing, * and a variant version that accepts numeric string, which is used to receive user input. kvm-pmu-filter object will take care of converting the string version of the event/counter information into the numeric version. The related implementation can be found in patch 1. CPU property v.s. KVM property ------------------------------ In Shaoqin's previous implementation [1], KVM PMU filter is made as a arm CPU property. This is because arm uses a per CPU ioctl (KVM_SET_DEVICE_ATTR) to configure KVM PMU filter. However, for x86, the dependent ioctl (KVM_SET_PMU_EVENT_FILTER) is per VM. In the meantime, considering that for hybrid architecture, maybe in the future there will be a new per vCPU ioctl, or there will be practices to support filter fixed counter by configuring CPUIDs. Based on the above thoughts, for x86, it is not appropriate to make the current per-VM ioctl-based PMU filter a CPU property. Instead, I make it a kvm property and configure it via "-accel kvm,pmu-filter=obj_id". So in summary, it is feasible to use the KVM PMU filter as either a CPU or a KVM property, depending on whether it is used as a CPU feature or a VM feature. The kvm-pmu-filter object, as an abstraction, is general enough to support filter configurations for different scopes (per-CPU or per-VM). [1]: https://lore.kernel.org/qemu-devel/20240409024940.180107-1-shahuang@redhat.com/ Thanks and Best Regards, Zhao --- Zhao Liu (5): qapi/qom: Introduce kvm-pmu-filter object i386/kvm: Support initial KVM PMU filter i386/kvm: Support event with select&umask format in KVM PMU filter i386/kvm: Support event with masked entry format in KVM PMU filter i386/kvm: Support fixed counter in KVM PMU filter MAINTAINERS | 1 + accel/kvm/kvm-pmu.c | 367 +++++++++++++++++++++++++++++++++++++ accel/kvm/meson.build | 1 + include/sysemu/kvm-pmu.h | 43 +++++ include/sysemu/kvm_int.h | 2 + qapi/kvm.json | 255 ++++++++++++++++++++++++++ qapi/meson.build | 1 + qapi/qapi-schema.json | 1 + qapi/qom.json | 3 + target/i386/kvm/kvm.c | 211 +++++++++++++++++++++ target/i386/kvm/kvm_i386.h | 1 + 11 files changed, 886 insertions(+) create mode 100644 accel/kvm/kvm-pmu.c create mode 100644 include/sysemu/kvm-pmu.h create mode 100644 qapi/kvm.json