From nobody Thu Jan 23 05:54:27 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1737457134; cv=none; d=zohomail.com; s=zohoarc; b=n1ApOIc9xgFMBMch+HB6W3qzIRMpJ9/OaamtLjt6tDsULB2hczoKonQCnxr232p3aVpJpQZTSdDfaXCHvKhPa8u/hZL7VjRMZ4rSTEuCXfPf1guY2mvW6VEPKTgEVT8xVmpZevMAaEl40oW4FDlndrKuIWFQGXrlvcypwxmIq0A= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1737457134; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=XxRDZtd5Utt5iRwmjAyBTVlmUz2KjyWXBIEy7zrcS7g=; b=mIZdAmYI8c27mHLt2/yNb/3pb9zeaqXaJJeVubU0NtI47G0VgNEFXbJLrH0cSl7Imxb7Gh4Plnab7L2+dCCCFHxA37dM01gReLbZAxwoQqie2HESNEjnFIJwEvMCWmia+ogfPGm6Pd5ShtAR4ssIMjkXUY2ro1aLAIwmydIxPWA= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1737457134458227.69454302232236; Tue, 21 Jan 2025 02:58:54 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1taBw9-0006hU-9I; Tue, 21 Jan 2025 05:56:49 -0500 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 1taBvs-0006eM-5k for qemu-devel@nongnu.org; Tue, 21 Jan 2025 05:56:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1taBvo-000567-2a for qemu-devel@nongnu.org; Tue, 21 Jan 2025 05:56:29 -0500 Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-621-wa6ChJUMNHuyVtQLXbHX1Q-1; Tue, 21 Jan 2025 05:56:25 -0500 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E81231956055 for ; Tue, 21 Jan 2025 10:56:24 +0000 (UTC) Received: from thuth-p1g4.redhat.com (unknown [10.39.192.56]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E535219560A7; Tue, 21 Jan 2025 10:56:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1737456987; 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: in-reply-to:in-reply-to:references:references; bh=XxRDZtd5Utt5iRwmjAyBTVlmUz2KjyWXBIEy7zrcS7g=; b=hTwF0T+8EhmomTi5M+IO0GWEIZeLg68+PsJ/SPfotplV/lL8U/BGo8esTxfHn3z+293ZfZ P6K043wdNmc4S9UQj3q32Y9Iy8z2UYQbcN6q5yfXkpIARrfdpP5p6pFtaIxa2Q55HiHJFh B38qgsTQIbAEd0nWojPIY3KA4eFrufk= X-MC-Unique: wa6ChJUMNHuyVtQLXbHX1Q-1 X-Mimecast-MFC-AGG-ID: wa6ChJUMNHuyVtQLXbHX1Q From: Thomas Huth To: qemu-devel@nongnu.org Cc: Stefan Hajnoczi , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , "Richard W.M. Jones" Subject: [PULL 3/9] crypto: fix bogus error benchmarking pbkdf on fast machines Date: Tue, 21 Jan 2025 11:56:05 +0100 Message-ID: <20250121105613.1286672-4-thuth@redhat.com> In-Reply-To: <20250121105613.1286672-1-thuth@redhat.com> References: <20250121105613.1286672-1-thuth@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-3, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1737457135353019000 From: Daniel P. Berrang=C3=A9 We're seeing periodic reports of errors like: $ qemu-img create -f luks --object secret,data=3D123456,id=3Dsec0 \ -o key-secret=3Dsec0 luks-info.img 1M Formatting 'luks-info.img', fmt=3Dluks size=3D1048576 key-secret=3Dsec0 qemu-img: luks-info.img: Unable to get accurate CPU usage This error message comes from a recent attempt to workaround a kernel bug with measuring rusage in long running processes: commit c72cab5ad9f849bbcfcf4be7952b8b8946cc626e Author: Tiago Pasqualini Date: Wed Sep 4 20:52:30 2024 -0300 crypto: run qcrypto_pbkdf2_count_iters in a new thread Unfortunately this has a subtle bug on machines which are very fast. On the first time around the loop, the 'iterations' value is quite small (1 << 15), and so will run quite fast. Testing has shown that some machines can complete this benchmarking task in as little as 7 milliseconds. Unfortunately the 'getrusage' data is not updated at the time of the 'getrusage' call, it is done asynchronously by the scheduler. The 7 millisecond completion time for the benchmark is short enough that 'getrusage' sometimes reports 0 accumulated execution time. As a result the 'delay_ms =3D=3D 0' sanity check in the above commit is triggering non-deterministically on such machines. The benchmarking loop intended to run multiple times, increasing the 'iterations' value until the benchmark ran for > 500 ms, but the sanity check doesn't allow this to happen. To fix it, we keep a loop counter and only run the sanity check after we've been around the loop more than 5 times. At that point the 'iterations' value is high enough that even with infrequent updates of 'getrusage' accounting data on fast machines, we should see a non-zero value. Fixes: https://lore.kernel.org/qemu-devel/ffe542bb-310c-4616-b0ca-13182f849= fd1@redhat.com/ Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=3D2336437 Reported-by: Thomas Huth Reported-by: Richard W.M. Jones Tested-by: Thomas Huth Signed-off-by: Daniel P. Berrang=C3=A9 Message-ID: <20250109093746.1216300-1-berrange@redhat.com> Signed-off-by: Thomas Huth --- crypto/pbkdf.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/crypto/pbkdf.c b/crypto/pbkdf.c index 0dd7c3aeaa..2989fc0a40 100644 --- a/crypto/pbkdf.c +++ b/crypto/pbkdf.c @@ -107,7 +107,7 @@ static void *threaded_qcrypto_pbkdf2_count_iters(void *= data) size_t nsalt =3D iters_data->nsalt; size_t nout =3D iters_data->nout; Error **errp =3D iters_data->errp; - + size_t scaled =3D 0; uint64_t ret =3D -1; g_autofree uint8_t *out =3D g_new(uint8_t, nout); uint64_t iterations =3D (1 << 15); @@ -131,7 +131,17 @@ static void *threaded_qcrypto_pbkdf2_count_iters(void = *data) =20 delta_ms =3D end_ms - start_ms; =20 - if (delta_ms =3D=3D 0) { /* sanity check */ + /* + * For very small 'iterations' values, CPU (or crypto + * accelerator) might be fast enough that the scheduler + * hasn't incremented getrusage() data, or incremented + * it by a very small amount, resulting in delta_ms =3D=3D 0. + * Once we've scaled 'iterations' x10, 5 times, we really + * should be seeing delta_ms !=3D 0, so sanity check at + * that point. + */ + if (scaled > 5 && + delta_ms =3D=3D 0) { /* sanity check */ error_setg(errp, "Unable to get accurate CPU usage"); goto cleanup; } else if (delta_ms > 500) { @@ -141,6 +151,7 @@ static void *threaded_qcrypto_pbkdf2_count_iters(void *= data) } else { iterations =3D (iterations * 1000 / delta_ms); } + scaled++; } =20 iterations =3D iterations * 1000 / delta_ms; --=20 2.48.1