From patchwork Tue Jul 19 02:08:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Gavin Shan X-Patchwork-Id: 592040 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 42FB5C43334 for ; Tue, 19 Jul 2022 00:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235547AbiGSAJR (ORCPT ); Mon, 18 Jul 2022 20:09:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236407AbiGSAJL (ORCPT ); Mon, 18 Jul 2022 20:09:11 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6ECB21FA for ; Mon, 18 Jul 2022 17:09:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1658189349; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=NEVx0pB2HnnThMov1umNo2N7MZ+/Y6MEAU+qrFJg/CQ=; b=X6VBX/3+3GzP8iqzHyJidvwtPSPc7HVwoK0kl5zR9lXdbEgo3FNwZ2W+1ydT7gLzCs1nb7 JibTfDqiFoHVCcmIpn6amBoSXbQwqhtAXsigZ0INpJXBpHPG0GvDnG97G4Sm/bXr8jCGsm Dvsj4hxwYLLZO3FHmJOybIv5wK40WAE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-438-GID_6yVGPdS7z3RsC3m02w-1; Mon, 18 Jul 2022 20:08:59 -0400 X-MC-Unique: GID_6yVGPdS7z3RsC3m02w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5A989811E7A; Tue, 19 Jul 2022 00:08:59 +0000 (UTC) Received: from gshan.redhat.com (vpn2-54-37.bne.redhat.com [10.64.54.37]) by smtp.corp.redhat.com (Postfix) with ESMTPS id F0E111121314; Tue, 19 Jul 2022 00:08:55 +0000 (UTC) From: Gavin Shan To: kvmarm@lists.cs.columbia.edu Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, oliver.upton@linux.dev, seanjc@google.com, shuah@kernel.org, maz@kernel.org, pbonzini@redhat.com, shan.gavin@gmail.com Subject: [PATCH v4] KVM: selftests: Fix target thread to be migrated in rseq_test Date: Tue, 19 Jul 2022 10:08:30 +0800 Message-Id: <20220719020830.3479482-1-gshan@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org In rseq_test, there are two threads, which are vCPU thread and migration worker separately. Unfortunately, the test has the wrong PID passed to sched_setaffinity() in the migration worker. It forces migration on the migration worker because zeroed PID represents the calling thread, which is the migration worker itself. It means the vCPU thread is never enforced to migration and it can migrate at any time, which eventually leads to failure as the following logs show. host# uname -r 5.19.0-rc6-gavin+ host# # cat /proc/cpuinfo | grep processor | tail -n 1 processor : 223 host# pwd /home/gavin/sandbox/linux.main/tools/testing/selftests/kvm host# for i in `seq 1 100`; do \ echo "--------> $i"; ./rseq_test; done --------> 1 --------> 2 --------> 3 --------> 4 --------> 5 --------> 6 ==== Test Assertion Failure ==== rseq_test.c:265: rseq_cpu == cpu pid=3925 tid=3925 errno=4 - Interrupted system call 1 0x0000000000401963: main at rseq_test.c:265 (discriminator 2) 2 0x0000ffffb044affb: ?? ??:0 3 0x0000ffffb044b0c7: ?? ??:0 4 0x0000000000401a6f: _start at ??:? rseq CPU = 4, sched CPU = 27 Fix the issue by passing correct parameter, TID of the vCPU thread, to sched_setaffinity() in the migration worker. Fixes: 61e52f1630f5 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs") Suggested-by: Sean Christopherson Signed-off-by: Gavin Shan Reviewed-by: Oliver Upton --- v4: Pick the code change as Sean suggested. --- tools/testing/selftests/kvm/rseq_test.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c index 4158da0da2bb..2237d1aac801 100644 --- a/tools/testing/selftests/kvm/rseq_test.c +++ b/tools/testing/selftests/kvm/rseq_test.c @@ -82,8 +82,9 @@ static int next_cpu(int cpu) return cpu; } -static void *migration_worker(void *ign) +static void *migration_worker(void *__rseq_tid) { + pid_t rseq_tid = (pid_t)(unsigned long)__rseq_tid; cpu_set_t allowed_mask; int r, i, cpu; @@ -106,7 +107,7 @@ static void *migration_worker(void *ign) * stable, i.e. while changing affinity is in-progress. */ smp_wmb(); - r = sched_setaffinity(0, sizeof(allowed_mask), &allowed_mask); + r = sched_setaffinity(rseq_tid, sizeof(allowed_mask), &allowed_mask); TEST_ASSERT(!r, "sched_setaffinity failed, errno = %d (%s)", errno, strerror(errno)); smp_wmb(); @@ -231,7 +232,8 @@ int main(int argc, char *argv[]) vm = vm_create_default(VCPU_ID, 0, guest_code); ucall_init(vm, NULL); - pthread_create(&migration_thread, NULL, migration_worker, 0); + pthread_create(&migration_thread, NULL, migration_worker, + (void *)(unsigned long)gettid()); for (i = 0; !done; i++) { vcpu_run(vm, VCPU_ID);