From patchwork Thu Jan 19 20:05:53 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Gardon X-Patchwork-Id: 13108754 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 976A2C46467 for ; Thu, 19 Jan 2023 20:06:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230154AbjASUGL (ORCPT ); Thu, 19 Jan 2023 15:06:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229561AbjASUGG (ORCPT ); Thu, 19 Jan 2023 15:06:06 -0500 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F3E89B103 for ; Thu, 19 Jan 2023 12:06:04 -0800 (PST) Received: by mail-pj1-x1049.google.com with SMTP id a2-20020a17090acb8200b00225c0839b80so1520275pju.5 for ; Thu, 19 Jan 2023 12:06:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=PyMfEnDnfrKdzg8f7h+BNuociXX2rPzzxU9yOiZlUe8=; b=kEVNJ+GeN1h23ubqyvE0mfJeF9VNrlK9q6YL1lr31A95rJzyqpJrojspBD/WSzHO9B 9QuUZ9ijr9YlXKIT99RWsd6PrVtU9MYzyNqbM/Oa/74Aqnh2d+XfZsBI9b57lJ3+Q9O3 +c7MCorkeTxxEOHkB+fidhmIqu/3/CqHDIkJ62naISxulYoIfcrD4WJDSxLkRCYEfBO4 8ACVJAhYXq6XyzqISFK27JoBQiQt1B6Q09soqxwbZJiNWQg3Lq7nuAbbcuS4tIqD0qfO U/gMIMvNCETNviaJFfpxU8ZihHMvnzYHn6xuECmptbubgKBqKZ1F19ZwDzjO1w6yrhIr hY4g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=PyMfEnDnfrKdzg8f7h+BNuociXX2rPzzxU9yOiZlUe8=; b=Q1qgHGtRD26z2ia+tGTPG+wv/qJRFxY7KJvRMm7RyLG+xleGNOM/Rbg+xLy0d3QDmw SVxpiSpnt1kZSoQOL6XRCXzZRqeHvvnzr0rKeIDCiv9gfkXmBmO5I8wICaQwBkw4Aq0W 3aaGqpHfkCLDGyamiYuP23DsjNb1gv8gTsmYVY6ABf59YqfN8QzTddMwCc4+AXIxTKoa z5TS88A3c0hdiaYYJQQeMR9THc6n8GUW5GzurrdD7OA1FwDrnK8Jag2a0E7Qz4R2YTGQ lRPJaTqgepRHCr6y/ZaRuRpq+MoMpB3Rj09GGddxzg1v/O0sBdD+qMM4vRgUkQ5t+cp8 3aPw== X-Gm-Message-State: AFqh2kq1yvDrmtIXmt7fL6yeZBsB2nm51QBV6TuH86AViUugTXYeJox/ ywVxBbpxEEJaBoM3QOvGUawgHkittwzW X-Google-Smtp-Source: AMrXdXuHuO+ALB4puSMNIZI3NBCa59oXxbNaarT1MGaM4fqwJuDQHjggdf8OPTtKjgVq/n7cb3/d0rqIdLzw X-Received: from sweer.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:e45]) (user=bgardon job=sendgmr) by 2002:a17:90a:9114:b0:229:f43c:4049 with SMTP id k20-20020a17090a911400b00229f43c4049mr3789pjo.0.1674158758851; Thu, 19 Jan 2023 12:05:58 -0800 (PST) Date: Thu, 19 Jan 2023 20:05:53 +0000 In-Reply-To: <20230119200553.3922206-1-bgardon@google.com> Mime-Version: 1.0 References: <20230119200553.3922206-1-bgardon@google.com> X-Mailer: git-send-email 2.39.1.405.gd4c25cc71f-goog Message-ID: <20230119200553.3922206-2-bgardon@google.com> Subject: [RFC 2/2] selftests: KVM: Add page splitting test From: Ben Gardon To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Peter Xu , Sean Christopherson , David Matlack , Vipin Sharma , Ben Gardon Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Add a test for page splitting during dirty logging and for hugepage recovery after dirty logging. Page splitting represents non-trivial behavior, which is complicated by MANUAL_PROTECT mode, which causes pages to be split on the first clear, instead of when dirty logging is enabled. Add a test which makes asserions about page counts to help define the expected behavior of page splitting and to provid needed coverage of the behavior. This also helps ensure that a failure in eager page splitting is not covered up by splitting in the vCPU path. Tested by running the test on an Intel Haswell machine w/wo MANUAL_PROTECT. Signed-off-by: Ben Gardon --- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/kvm_util_base.h | 1 + .../kvm/x86_64/page_splitting_test.c | 311 ++++++++++++++++++ 3 files changed, 313 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/page_splitting_test.c diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 1750f91dd9362..057ebd709e77a 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -76,6 +76,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test TEST_GEN_PROGS_x86_64 += x86_64/nested_exceptions_test +TEST_GEN_PROGS_x86_64 += x86_64/page_splitting_test TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h index fbc2a79369b8b..98974a601b0af 100644 --- a/tools/testing/selftests/kvm/include/kvm_util_base.h +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h @@ -402,6 +402,7 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name) uint64_t data; __vm_get_stat(vm, stat_name, &data, 1); + return data; } diff --git a/tools/testing/selftests/kvm/x86_64/page_splitting_test.c b/tools/testing/selftests/kvm/x86_64/page_splitting_test.c new file mode 100644 index 0000000000000..4b5dcd4908b5a --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/page_splitting_test.c @@ -0,0 +1,311 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KVM dirty logging page splitting test + * + * Based on dirty_log_perf.c + * + * Copyright (C) 2018, Red Hat, Inc. + * Copyright (C) 2020, Google, Inc. + */ + +#include +#include +#include +#include +#include + +#include "kvm_util.h" +#include "test_util.h" +#include "memstress.h" +#include "guest_modes.h" + +/* How many host loops to run by default (one KVM_GET_DIRTY_LOG for each loop)*/ +#define TEST_HOST_LOOP_N 2UL + +static int NR_VCPUS = 2; +static int NR_SLOTS = 2; +static int NR_ITERATIONS = 2; +static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE; + +/* Host variables */ +static u64 dirty_log_manual_caps; +static bool host_quit; +static int iteration; +static int vcpu_last_completed_iteration[KVM_MAX_VCPUS]; + +struct kvm_page_stats { + uint64_t pages_4k; + uint64_t pages_2m; + uint64_t pages_1g; + uint64_t hugepages; +}; + +static void get_page_stats(struct kvm_vm *vm, struct kvm_page_stats *stats) +{ + stats->pages_4k = vm_get_stat(vm, "pages_4k"); + stats->pages_2m = vm_get_stat(vm, "pages_2m"); + stats->pages_1g = vm_get_stat(vm, "pages_1g"); + stats->hugepages = stats->pages_2m + stats->pages_1g; + + pr_debug("Page stats - 4K: %ld 2M: %ld 1G: %ld huge: %ld\n", + stats->pages_4k, stats->pages_2m, stats->pages_1g, + stats->hugepages); +} + +static void vcpu_worker(struct memstress_vcpu_args *vcpu_args) +{ + struct kvm_vcpu *vcpu = vcpu_args->vcpu; + int vcpu_idx = vcpu_args->vcpu_idx; + uint64_t pages_count = 0; + struct kvm_run *run; + int ret; + + run = vcpu->run; + + while (!READ_ONCE(host_quit)) { + int current_iteration = READ_ONCE(iteration); + + ret = _vcpu_run(vcpu); + + TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret); + TEST_ASSERT(get_ucall(vcpu, NULL) == UCALL_SYNC, + "Invalid guest sync status: exit_reason=%s\n", + exit_reason_str(run->exit_reason)); + + vcpu_last_completed_iteration[vcpu_idx] = current_iteration; + + if (current_iteration) + pages_count += vcpu_args->pages; + + /* Wait for the start of the next iteration to be signaled. */ + while (current_iteration == READ_ONCE(iteration) && + READ_ONCE(iteration) >= 0 && + !READ_ONCE(host_quit)) + ; + } +} + +struct test_params { + enum vm_mem_backing_src_type backing_src; +}; + +static void run_test(struct test_params *p) +{ + struct kvm_vm *vm; + unsigned long **bitmaps; + uint64_t guest_num_pages; + uint64_t host_num_pages; + uint64_t pages_per_slot; + int i; + uint64_t total_4k_pages; + struct kvm_page_stats stats_populated; + struct kvm_page_stats stats_dirty_logging_enabled; + struct kvm_page_stats stats_dirty_pass[NR_ITERATIONS]; + struct kvm_page_stats stats_clear_pass[NR_ITERATIONS]; + struct kvm_page_stats stats_dirty_logging_disabled; + struct kvm_page_stats stats_repopulated; + + vm = memstress_create_vm(VM_MODE_DEFAULT, NR_VCPUS, guest_percpu_mem_size, + NR_SLOTS, p->backing_src, false); + + guest_num_pages = (NR_VCPUS * guest_percpu_mem_size) >> vm->page_shift; + guest_num_pages = vm_adjust_num_guest_pages(VM_MODE_DEFAULT, guest_num_pages); + host_num_pages = vm_num_host_pages(VM_MODE_DEFAULT, guest_num_pages); + pages_per_slot = host_num_pages / NR_SLOTS; + + bitmaps = memstress_alloc_bitmaps(NR_SLOTS, pages_per_slot); + + if (dirty_log_manual_caps) + vm_enable_cap(vm, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2, + dirty_log_manual_caps); + + /* Start the iterations */ + iteration = 0; + host_quit = false; + + for (i = 0; i < NR_VCPUS; i++) + vcpu_last_completed_iteration[i] = -1; + + memstress_start_vcpu_threads(NR_VCPUS, vcpu_worker); + + /* Allow the vCPUs to populate memory */ + for (i = 0; i < NR_VCPUS; i++) { + while (READ_ONCE(vcpu_last_completed_iteration[i]) != + iteration) + ; + } + + pr_debug("\nGetting stats after populating memory:\n"); + get_page_stats(vm, &stats_populated); + + /* Enable dirty logging */ + memstress_enable_dirty_logging(vm, NR_SLOTS); + + pr_debug("\nGetting stats after enabling dirty logging:\n"); + get_page_stats(vm, &stats_dirty_logging_enabled); + + while (iteration < NR_ITERATIONS) { + /* + * Incrementing the iteration number will start the vCPUs + * dirtying memory again. + */ + iteration++; + + for (i = 0; i < NR_VCPUS; i++) { + while (READ_ONCE(vcpu_last_completed_iteration[i]) + != iteration) + ; + } + + pr_debug("\nGetting stats after dirtying memory on pass %d:\n", iteration); + get_page_stats(vm, &stats_dirty_pass[iteration - 1]); + + memstress_get_dirty_log(vm, bitmaps, NR_SLOTS); + + if (dirty_log_manual_caps) { + memstress_clear_dirty_log(vm, bitmaps, NR_SLOTS, pages_per_slot); + + pr_debug("\nGetting stats after clearing dirty log pass %d:\n", iteration); + get_page_stats(vm, &stats_clear_pass[iteration - 1]); + } + } + + /* Disable dirty logging */ + memstress_disable_dirty_logging(vm, NR_SLOTS); + + pr_debug("\nGetting stats after disabling dirty logging:\n"); + get_page_stats(vm, &stats_dirty_logging_disabled); + + /* Run vCPUs again to fault pages back in. */ + iteration++; + for (i = 0; i < NR_VCPUS; i++) { + while (READ_ONCE(vcpu_last_completed_iteration[i]) != iteration) + ; + } + + pr_debug("\nGetting stats after repopulating memory:\n"); + get_page_stats(vm, &stats_repopulated); + + /* + * Tell the vCPU threads to quit. No need to manually check that vCPUs + * have stopped running after disabling dirty logging, the join will + * wait for them to exit. + */ + host_quit = true; + memstress_join_vcpu_threads(NR_VCPUS); + + memstress_free_bitmaps(bitmaps, NR_SLOTS); + memstress_destroy_vm(vm); + + /* Make assertions about the page counts. */ + total_4k_pages = stats_populated.pages_4k; + total_4k_pages += stats_populated.pages_2m * 512; + total_4k_pages += stats_populated.pages_1g * 512 * 512; + + /* + * Check that all huge pages were split. Since large pages can only + * exist in the data slot, and the vCPUs should have dirtied all pages + * in the data slot, there should be no huge pages left after splitting. + * Splitting happens at dirty log enable time without + * KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 and after the first clear pass + * with that capability. + */ + if (dirty_log_manual_caps) { + TEST_ASSERT(stats_clear_pass[0].hugepages == 0, + "Unexpected huge page count after splitting. Expected 0, got %ld", + stats_clear_pass[0].hugepages); + TEST_ASSERT(stats_clear_pass[0].pages_4k == total_4k_pages, + "All memory should be mapped at 4k. Expected %ld 4k pages, got %ld", + total_4k_pages, stats_clear_pass[0].pages_4k); + } else { + TEST_ASSERT(stats_dirty_logging_enabled.hugepages == 0, + "Unexpected huge page count after splitting. Expected 0, got %ld", + stats_dirty_logging_enabled.hugepages); + TEST_ASSERT(stats_dirty_logging_enabled.pages_4k == total_4k_pages, + "All memory should be mapped at 4k. Expected %ld 4k pages, got %ld", + total_4k_pages, stats_dirty_logging_enabled.pages_4k); + } + + /* + * Once dirty logging is disabled and the vCPUs have touched all their + * memory again, the page counts should be the same as they were + * right after initial population of memory. + */ + TEST_ASSERT(stats_populated.pages_4k == stats_repopulated.pages_4k, + "4k page count did not return to its initial value after " + "dirty logging. Expected %ld, got %ld", + stats_populated.pages_4k, stats_repopulated.pages_4k); + TEST_ASSERT(stats_populated.pages_2m == stats_repopulated.pages_2m, + "2m page count did not return to its initial value after " + "dirty logging. Expected %ld, got %ld", + stats_populated.pages_2m, stats_repopulated.pages_2m); + TEST_ASSERT(stats_populated.pages_1g == stats_repopulated.pages_1g, + "1g page count did not return to its initial value after " + "dirty logging. Expected %ld, got %ld", + stats_populated.pages_1g, stats_repopulated.pages_1g); +} + +static void help(char *name) +{ + puts(""); + printf("usage: %s [-h] [-g] [-m mode] [-b vcpu bytes] [-s mem type]\n", + name); + puts(""); + printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n" + " makes KVM_GET_DIRTY_LOG clear the dirty log (i.e.\n" + " KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE is not enabled)\n" + " and writes will be tracked as soon as dirty logging is\n" + " enabled on the memslot (i.e. KVM_DIRTY_LOG_INITIALLY_SET\n" + " is not enabled).\n"); + printf(" -b: specify the size of the memory region which should be\n" + " dirtied by each vCPU. e.g. 10M or 3G.\n" + " (default: 1G)\n"); + backing_src_help("-s"); + puts(""); + exit(0); +} + +int main(int argc, char *argv[]) +{ + struct test_params p = { + .backing_src = VM_MEM_SRC_ANONYMOUS_HUGETLB, + }; + int opt; + + dirty_log_manual_caps = + kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2); + dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | + KVM_DIRTY_LOG_INITIALLY_SET); + + guest_modes_append_default(); + + while ((opt = getopt(argc, argv, "b:ghs:")) != -1) { + switch (opt) { + case 'b': + guest_percpu_mem_size = parse_size(optarg); + break; + case 'g': + dirty_log_manual_caps = 0; + break; + case 'h': + help(argv[0]); + break; + case 's': + p.backing_src = parse_backing_src_type(optarg); + break; + default: + help(argv[0]); + break; + } + } + + if (!is_backing_src_hugetlb(p.backing_src)) { + pr_info("This test will only work reliably with HugeTLB memory. " + "It can work with THP, but that is best effort."); + return KSFT_SKIP; + } + + run_test(&p); + + return 0; +}