From patchwork Fri Jan 12 05:53:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shaoqin Huang X-Patchwork-Id: 187581 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:7300:2411:b0:101:2151:f287 with SMTP id m17csp1926776dyi; Thu, 11 Jan 2024 21:54:49 -0800 (PST) X-Google-Smtp-Source: AGHT+IExdZZn2ocxcFq97muRr1G26hPs5I+fifasgvGh+Va6JrTE3bNp7eXXBCrcInn0lSdryi6l X-Received: by 2002:aa7:d997:0:b0:557:708d:3579 with SMTP id u23-20020aa7d997000000b00557708d3579mr354832eds.18.1705038889131; Thu, 11 Jan 2024 21:54:49 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1705038889; cv=none; d=google.com; s=arc-20160816; b=aUT4p2bELErsVO+H1K5saLcwQSvVcwK/gHb1SvyiDPKL/hc9+bZD7WKMmBaPgcCHOY n+yx1+eL8Fd6neggBSL/q4WfyNOKnN6xjKM3M6aUaEkba+eBq/CsqSc1wf26BPUHZSkk SsoE1cRpA1oLG0QYQrVVrrLL5miBLkoRvUyy3K36gWD7A2SAunbWLuLkHzZvGCUNq6iW tjacwL6ZX05DS5YpBikF0/V4iVMv4hvjqVt/ydSfuESy2RlKJ938ijChp/JJyBM3CKzb pquwoq+oSWhghsQxvAWpOEbJ44Fv8uuhXBoMuLk0qPRKdsP02KBzIatAPT6KJ9yZ/UvP XWIg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:list-unsubscribe :list-subscribe:list-id:precedence:message-id:date:subject:cc:to :from:dkim-signature; bh=GP1qDRaGGYNkvm0KV8/GWSP2DF/3SQkemClyjrO5cH0=; fh=gg2S/NH6mAOLgAhlwgYStEZ8nPD/NS4k6nuZ1Bg5fAo=; b=Mb2eJSO55aCHxBQvfV2a80j2jm4OHww0IXOC9Bbi/9iLH56QJrRwhKKNO5wN+bE4L1 roja1f/q1EOyA6hqi4k+71y/u0bRQJLTJTs0E2/qyVBfe47/U6T9wtvv7oc1ZYoUpt/X uxgDN0+nMyRt83uDf52GzKDJDIZbJvzgqeCJa14tkrWmAnlOSFRNtmmPxHkKA5Pulm4C R4VTTp6fYJz42nbYJDOBKqRIA4IqNeJfeO6TP4RKrcQUoIYcBGqwS+UGKtg5JO2sColK /Bq8LMxiCjj1MV9U60EveqbOpJ77x4covTP8nnQ+r9XcKNzPrmkYeW918yCfLgSJ5pdv YJTQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=HLV487+N; spf=pass (google.com: domain of linux-kernel+bounces-24331-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) smtp.mailfrom="linux-kernel+bounces-24331-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from am.mirrors.kernel.org (am.mirrors.kernel.org. [147.75.80.249]) by mx.google.com with ESMTPS id a17-20020a05640213d100b00557c2158c99si1200084edx.259.2024.01.11.21.54.48 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jan 2024 21:54:49 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-24331-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=HLV487+N; spf=pass (google.com: domain of linux-kernel+bounces-24331-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) smtp.mailfrom="linux-kernel+bounces-24331-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id B82B41F26A83 for ; Fri, 12 Jan 2024 05:54:48 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E56615C8E0; Fri, 12 Jan 2024 05:54:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HLV487+N" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E30E5C8E1 for ; Fri, 12 Jan 2024 05:54:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705038855; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=GP1qDRaGGYNkvm0KV8/GWSP2DF/3SQkemClyjrO5cH0=; b=HLV487+NzSsBjIfOkTb7gWLs4XhclLkzE8SMgkZowmv7R+qviZoqrbHYcfTOjD3jZbI9dp qmQsYs7Roex4TYIwUrstcvj8jAwCeqr50t+Qnviil5Ew1/G5hpCOxin+cqjyIWWg08mnJ6 tWEQmb4N3K2HQmQebKoF2JFrs/Snqxg= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-91-nYBvnK9GMumwfMd65qae7A-1; Fri, 12 Jan 2024 00:53:46 -0500 X-MC-Unique: nYBvnK9GMumwfMd65qae7A-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E5F6B85A588; Fri, 12 Jan 2024 05:53:45 +0000 (UTC) Received: from virt-mtcollins-01.lab.eng.rdu2.redhat.com (virt-mtcollins-01.lab.eng.rdu2.redhat.com [10.8.1.196]) by smtp.corp.redhat.com (Postfix) with ESMTP id CA8BE2026D66; Fri, 12 Jan 2024 05:53:45 +0000 (UTC) From: Shaoqin Huang To: Paolo Bonzini , Sean Christopherson Cc: Oliver Upton , Marc Zyngier , Peter Xu , kvmarm@lists.linux.dev, Shaoqin Huang , Shuah Khan , kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] KVM: selftests: Fix the dirty_log_test semaphore imbalance Date: Fri, 12 Jan 2024 00:53:39 -0500 Message-Id: <20240112055340.19372-1-shahuang@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1787862858077120094 X-GMAIL-MSGID: 1787862858077120094 When execute the dirty_log_test on some aarch64 machine, it sometimes trigger the ASSERT: ==== Test Assertion Failure ==== dirty_log_test.c:384: dirty_ring_vcpu_ring_full pid=14854 tid=14854 errno=22 - Invalid argument 1 0x00000000004033eb: dirty_ring_collect_dirty_pages at dirty_log_test.c:384 2 0x0000000000402d27: log_mode_collect_dirty_pages at dirty_log_test.c:505 3 (inlined by) run_test at dirty_log_test.c:802 4 0x0000000000403dc7: for_each_guest_mode at guest_modes.c:100 5 0x0000000000401dff: main at dirty_log_test.c:941 (discriminator 3) 6 0x0000ffff9be173c7: ?? ??:0 7 0x0000ffff9be1749f: ?? ??:0 8 0x000000000040206f: _start at ??:? Didn't continue vcpu even without ring full The dirty_log_test fails when execute the dirty-ring test, this is because the sem_vcpu_cont and the sem_vcpu_stop is non-zero value when execute the dirty_ring_collect_dirty_pages() function. When those two sem_t variables are non-zero, the dirty_ring_wait_vcpu() at the beginning of the dirty_ring_collect_dirty_pages() will not wait for the vcpu to stop, but continue to execute the following code. In this case, before vcpu stop, if the dirty_ring_vcpu_ring_full is true, and the dirty_ring_collect_dirty_pages() has passed the check for the dirty_ring_vcpu_ring_full but hasn't execute the check for the continued_vcpu, the vcpu stop, and set the dirty_ring_vcpu_ring_full to false. Then dirty_ring_collect_dirty_pages() will trigger the ASSERT. Why sem_vcpu_cont and sem_vcpu_stop can be non-zero value? It's because the dirty_ring_before_vcpu_join() execute the sem_post(&sem_vcpu_cont) at the end of each dirty-ring test. It can cause two cases: 1. sem_vcpu_cont be non-zero. When we set the host_quit to be true, the vcpu_worker directly see the host_quit to be true, it quit. So the log_mode_before_vcpu_join() function will set the sem_vcpu_cont to 1, since the vcpu_worker has quit, it won't consume it. 2. sem_vcpu_stop be non-zero. When we set the host_quit to be true, the vcpu_worker has entered the guest state, the next time it exit from guest state, it will set the sem_vcpu_stop to 1, and then see the host_quit, no one will consume the sem_vcpu_stop. When execute more and more dirty-ring tests, the sem_vcpu_cont and sem_vcpu_stop can be larger and larger, which makes many code paths don't wait for the sem_t. Thus finally cause the problem. To fix this problem, we can wait a while before set the host_quit to true, which gives the vcpu time to enter the guest state, so it will exit again. Then we can wait the vcpu to exit, and let it continue again, then the vcpu will see the host_quit. Thus the sem_vcpu_cont and sem_vcpu_stop will be both zero when test finished. Signed-off-by: Shaoqin Huang --- v1->v2: - Fix the real logic bug, not just fresh the context. v1: https://lore.kernel.org/all/20231116093536.22256-1-shahuang@redhat.com/ --- tools/testing/selftests/kvm/dirty_log_test.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c index 936f3a8d1b83..a6e0ff46a07c 100644 --- a/tools/testing/selftests/kvm/dirty_log_test.c +++ b/tools/testing/selftests/kvm/dirty_log_test.c @@ -417,7 +417,8 @@ static void dirty_ring_after_vcpu_run(struct kvm_vcpu *vcpu, int ret, int err) static void dirty_ring_before_vcpu_join(void) { - /* Kick another round of vcpu just to make sure it will quit */ + /* Wait vcpu exit, and let it continue to see the host_quit. */ + dirty_ring_wait_vcpu(); sem_post(&sem_vcpu_cont); } @@ -719,6 +720,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) struct kvm_vm *vm; unsigned long *bmap; uint32_t ring_buf_idx = 0; + int sem_val; if (!log_mode_supported()) { print_skip("Log mode '%s' not supported", @@ -726,6 +728,11 @@ static void run_test(enum vm_guest_mode mode, void *arg) return; } + sem_getvalue(&sem_vcpu_stop, &sem_val); + assert(sem_val == 0); + sem_getvalue(&sem_vcpu_cont, &sem_val); + assert(sem_val == 0); + /* * We reserve page table for 2 times of extra dirty mem which * will definitely cover the original (1G+) test range. Here @@ -825,6 +832,13 @@ static void run_test(enum vm_guest_mode mode, void *arg) sync_global_to_guest(vm, iteration); } + /* + * + * Before we set the host_quit, let the vcpu has time to run, to make + * sure we consume the sem_vcpu_stop and the vcpu consume the + * sem_vcpu_cont, to keep the semaphore balance. + */ + usleep(p->interval * 1000); /* Tell the vcpu thread to quit */ host_quit = true; log_mode_before_vcpu_join();