From patchwork Thu Sep 16 18:15:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oliver Upton X-Patchwork-Id: 12500045 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21611C433EF for ; Thu, 16 Sep 2021 18:56:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CE9760E52 for ; Thu, 16 Sep 2021 18:56:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236175AbhIPS6K (ORCPT ); Thu, 16 Sep 2021 14:58:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241917AbhIPS5e (ORCPT ); Thu, 16 Sep 2021 14:57:34 -0400 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4CE8C04A162 for ; Thu, 16 Sep 2021 11:16:07 -0700 (PDT) Received: by mail-qv1-xf49.google.com with SMTP id j4-20020ad454c4000000b0037a900dda7aso63133856qvx.14 for ; Thu, 16 Sep 2021 11:16:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=Jo3jDqyeYJxHTghdjTSap/sGN1bxajOYxVwklxu7bWA=; b=pWQvEGHm7bH1GMoSyq55V3ReY1YWle4IuUb8kruzdacZ4VmBhZuy/dsiBGld1eWAWu VnM5YsMlT2tx4amwEWzQa8jFI64K9cvTtbU6T4xKWsrb6eMWZdta8qPZt+mTwfHlOVG/ URpoaWL8fEaqR3YJNWi2jYhsvuEItlvyALgXgVoNGNF1fxJsn0yIAPK5W2qTD4NoiQqX FzLf1I955MRZRQ776dVyXYg27ZXw99UzznImKCa+BGMtyBG8fBTeWHNjWix36y39YIZE FR7Y8D1hyWKwco9OmQgDTvlhdJh6b1zwLMSu8omzxXZHNeLZxA8fTSm1DvM0PGIGDi9/ RiRA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=Jo3jDqyeYJxHTghdjTSap/sGN1bxajOYxVwklxu7bWA=; b=iTsENqCEc0HCSGJAgnSyrO2mL1ZiKCxiyph+9QPkf9uS3IVGXtkErqw8+H2SbDM+9t oJ/dNtQLPOuhFv/fW5zY8Cdj4WSPaHteffN/9sj+2ng4tAf/16NR5DxAspYXM3EFapHp gdfXi2Kiiaahkw3rnCsMs6VIWKZOFPHYnNaBEnPKZ5FuLZvN7D8pbprmWtwa8JlcIpbC SZdETS/c3MjWG+oOqePGQfywxcUrSmYZXXYlmqdyPMy1Z72Q5mXJE4Tw039K9edOPFwB fGivKsrtx2suDsKP/lVF+tclcdwl+FwkWIahn6SMO+wqaBt0KbDATV9eM6VJwiMcn+Vc o+QA== X-Gm-Message-State: AOAM530ghR+176vWuv1hQasQrzv/SWEQROvXOSf6SJHb43SOAWjVKwXn GKGGy5FOqnLg5NEGACXtrUyFeC/mUGLu4SoQ8nedddUDECoowPYEvEHQnkyG+tjJ296sgc3Koyj WebWCHH8mI62vMpf2t41YJsGUfo9LgIextEDj+OCH1QTHzICPHzCbvD8LGQ== X-Google-Smtp-Source: ABdhPJwDiSi0ZPRJseGEFzbAQlsEdEq5dnm1i+UY0kiUdKyUyLjB/6Jh3NrJjzqszbTMYIxokAGG2QBgAjw= X-Received: from oupton.c.googlers.com ([fda3:e722:ac3:cc00:2b:ff92:c0a8:404]) (user=oupton job=sendgmr) by 2002:a05:6214:431:: with SMTP id a17mr6551202qvy.48.1631816166794; Thu, 16 Sep 2021 11:16:06 -0700 (PDT) Date: Thu, 16 Sep 2021 18:15:54 +0000 In-Reply-To: <20210916181555.973085-1-oupton@google.com> Message-Id: <20210916181555.973085-9-oupton@google.com> Mime-Version: 1.0 References: <20210916181555.973085-1-oupton@google.com> X-Mailer: git-send-email 2.33.0.464.g1972c5931b-goog Subject: [PATCH v8 8/9] selftests: KVM: Add counter emulation benchmark From: Oliver Upton To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu Cc: Paolo Bonzini , Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Andrew Jones , Will Deacon , Catalin Marinas , Oliver Upton Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Add a test case for counter emulation on arm64. A side effect of how KVM handles physical counter offsetting on non-ECV systems is that the virtual counter will always hit hardware and the physical could be emulated. Force emulation by writing a nonzero offset to the physical counter and compare the elapsed cycles to a direct read of the hardware register. Reviewed-by: Ricardo Koller Signed-off-by: Oliver Upton Reviewed-by: Andrew Jones --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../kvm/aarch64/counter_emulation_benchmark.c | 207 ++++++++++++++++++ 3 files changed, 209 insertions(+) create mode 100644 tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index aa5a5197716e..ae2564b27af0 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -1,4 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only +/aarch64/counter_emulation_benchmark /aarch64/debug-exceptions /aarch64/get-reg-list /aarch64/psci_cpu_on_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index fd61d0063c50..3c80899b40ee 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -86,6 +86,7 @@ TEST_GEN_PROGS_x86_64 += steal_time TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test TEST_GEN_PROGS_x86_64 += system_counter_offset_test +TEST_GEN_PROGS_aarch64 += aarch64/counter_emulation_benchmark TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list TEST_GEN_PROGS_aarch64 += aarch64/psci_cpu_on_test diff --git a/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c new file mode 100644 index 000000000000..48dbd9459102 --- /dev/null +++ b/tools/testing/selftests/kvm/aarch64/counter_emulation_benchmark.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * counter_emulation_benchmark.c -- test to measure the effects of counter + * emulation on guest reads of the physical counter. + * + * Copyright (c) 2021, Google LLC. + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include + +#include "kvm_util.h" +#include "processor.h" +#include "test_util.h" + +#define VCPU_ID 0 + +static struct counter_values { + uint64_t cntvct_start; + uint64_t cntpct; + uint64_t cntvct_end; +} counter_values; + +static uint64_t nr_iterations = 1000; + +static void do_test(void) +{ + /* + * Open-coded approach instead of using helper methods to keep a tight + * interval around the physical counter read. + */ + asm volatile("isb\n\t" + "mrs %[cntvct_start], cntvct_el0\n\t" + "isb\n\t" + "mrs %[cntpct], cntpct_el0\n\t" + "isb\n\t" + "mrs %[cntvct_end], cntvct_el0\n\t" + "isb\n\t" + : [cntvct_start] "=r"(counter_values.cntvct_start), + [cntpct] "=r"(counter_values.cntpct), + [cntvct_end] "=r"(counter_values.cntvct_end)); +} + +static void guest_main(void) +{ + int i; + + for (i = 0; i < nr_iterations; i++) { + do_test(); + GUEST_SYNC(i); + } + + for (i = 0; i < nr_iterations; i++) { + do_test(); + GUEST_SYNC(i); + } +} + +static void enter_guest(struct kvm_vm *vm) +{ + struct ucall uc; + + vcpu_ioctl(vm, VCPU_ID, KVM_RUN, NULL); + + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_SYNC: + break; + case UCALL_ABORT: + TEST_ASSERT(false, "%s at %s:%ld", (const char *)uc.args[0], + __FILE__, uc.args[1]); + break; + default: + TEST_ASSERT(false, "unexpected exit: %s", + exit_reason_str(vcpu_state(vm, VCPU_ID)->exit_reason)); + break; + } +} + +static double counter_frequency(void) +{ + uint32_t freq; + + asm volatile("mrs %0, cntfrq_el0" + : "=r" (freq)); + + return freq / 1000000.0; +} + +static void log_csv(FILE *csv, bool trapped) +{ + double freq = counter_frequency(); + + fprintf(csv, "%s,%.02f,%lu,%lu,%lu\n", + trapped ? "true" : "false", freq, + counter_values.cntvct_start, + counter_values.cntpct, + counter_values.cntvct_end); +} + +static double run_loop(struct kvm_vm *vm, FILE *csv, bool trapped) +{ + double avg = 0; + int i; + + for (i = 0; i < nr_iterations; i++) { + uint64_t delta; + + enter_guest(vm); + sync_global_from_guest(vm, counter_values); + + if (csv) + log_csv(csv, trapped); + + delta = counter_values.cntvct_end - counter_values.cntvct_start; + avg = ((avg * i) + delta) / (i + 1); + } + + return avg; +} + +static void setup_counter(struct kvm_vm *vm, uint64_t offset) +{ + vcpu_access_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL, + KVM_ARM_VCPU_TIMER_PHYS_OFFSET, &offset, + true); +} + +static void run_tests(struct kvm_vm *vm, FILE *csv) +{ + double avg_trapped, avg_native, freq; + + freq = counter_frequency(); + + if (csv) + fputs("trapped,freq_mhz,cntvct_start,cntpct,cntvct_end\n", csv); + + /* no physical offsetting; kvm allows reads of cntpct_el0 */ + setup_counter(vm, 0); + avg_native = run_loop(vm, csv, false); + + /* force emulation of the physical counter */ + setup_counter(vm, 1); + avg_trapped = run_loop(vm, csv, true); + + pr_info("%lu iterations: average cycles (@%.02fMHz) native: %.02f, trapped: %.02f\n", + nr_iterations, freq, avg_native, avg_trapped); +} + +static void usage(const char *program_name) +{ + fprintf(stderr, + "Usage: %s [-h] [-o csv_file] [-n iterations]\n" + " -h prints this message\n" + " -n number of test iterations (default: %lu)\n" + " -o csv file to write data\n", + program_name, nr_iterations); +} + +int main(int argc, char **argv) +{ + struct kvm_vm *vm; + FILE *csv = NULL; + int opt; + + while ((opt = getopt(argc, argv, "hn:o:")) != -1) { + switch (opt) { + case 'o': + csv = fopen(optarg, "w"); + if (!csv) { + fprintf(stderr, "failed to open file '%s': %d\n", + optarg, errno); + exit(1); + } + break; + case 'n': + nr_iterations = strtoul(optarg, NULL, 0); + break; + default: + fprintf(stderr, "unrecognized option: '-%c'\n", opt); + /* fallthrough */ + case 'h': + usage(argv[0]); + exit(1); + } + } + + vm = vm_create_default(VCPU_ID, 0, guest_main); + sync_global_to_guest(vm, nr_iterations); + ucall_init(vm, NULL); + + if (_vcpu_has_device_attr(vm, VCPU_ID, KVM_ARM_VCPU_TIMER_CTRL, + KVM_ARM_VCPU_TIMER_PHYS_OFFSET)) { + print_skip("KVM_ARM_VCPU_TIMER_PHYS_OFFSET not supported."); + exit(KSFT_SKIP); + } + + run_tests(vm, csv); + kvm_vm_free(vm); + + if (csv) + fclose(csv); +}