From patchwork Sat Dec 16 17:41:32 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Berger X-Patchwork-Id: 10117305 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id A667660327 for ; Sat, 16 Dec 2017 17:59:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8C72329299 for ; Sat, 16 Dec 2017 17:59:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 81372292A5; Sat, 16 Dec 2017 17:59:00 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 24C6B29299 for ; Sat, 16 Dec 2017 17:59:00 +0000 (UTC) Received: from localhost ([::1]:51572 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQGjj-0002Gu-CZ for patchwork-qemu-devel@patchwork.kernel.org; Sat, 16 Dec 2017 12:58:59 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45931) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eQGTj-000635-Cy for qemu-devel@nongnu.org; Sat, 16 Dec 2017 12:42:30 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eQGTf-0008UX-C3 for qemu-devel@nongnu.org; Sat, 16 Dec 2017 12:42:27 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45830 helo=mx0a-001b2d01.pphosted.com) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eQGTf-0008Ty-63 for qemu-devel@nongnu.org; Sat, 16 Dec 2017 12:42:23 -0500 Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vBGHdUdn134491 for ; Sat, 16 Dec 2017 12:42:22 -0500 Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) by mx0b-001b2d01.pphosted.com with ESMTP id 2ew0h5k70f-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Sat, 16 Dec 2017 12:42:22 -0500 Received: from localhost by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Sat, 16 Dec 2017 10:42:19 -0700 Received: from b03ledav001.gho.boulder.ibm.com (b03ledav001.gho.boulder.ibm.com [9.17.130.232]) by b03cxnp08025.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id vBGHgJGH10355028; Sat, 16 Dec 2017 10:42:19 -0700 Received: from b03ledav001.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EED4C6E035; Sat, 16 Dec 2017 10:42:18 -0700 (MST) Received: from sbct-3.watson.ibm.com (unknown [9.47.158.153]) by b03ledav001.gho.boulder.ibm.com (Postfix) with ESMTP id 825566E03F; Sat, 16 Dec 2017 10:42:18 -0700 (MST) From: Stefan Berger To: qemu-devel@nongnu.org Date: Sat, 16 Dec 2017 12:41:32 -0500 X-Mailer: git-send-email 2.5.5 In-Reply-To: <1513446109-9013-1-git-send-email-stefanb@linux.vnet.ibm.com> References: <1513446109-9013-1-git-send-email-stefanb@linux.vnet.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 x-cbid: 17121617-0024-0000-0000-000017A9EF5C X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008213; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000244; SDB=6.00961141; UDB=6.00486146; IPR=6.00741136; BA=6.00005744; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00018575; XFM=3.00000015; UTC=2017-12-16 17:42:20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17121617-0025-0000-0000-00004DEC1151 Message-Id: <1513446109-9013-16-git-send-email-stefanb@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-12-16_11:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712160265 X-MIME-Autoconverted: from 8bit to quoted-printable by mx0b-001b2d01.pphosted.com id vBGHdUdn134491 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.158.5 Subject: [Qemu-devel] [PULL v1 15/32] tpm-passthrough: workaround a possible race X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, Stefan Berger , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Marc-André Lureau The TPM backend processing thread has common shared variable race issues. (they should not be so easy to reach since guest interaction with the device is slow compared to host emulation) An obvious one is setting op_cancelled from device thread after calling write(cancel_fd). The backend thread may return before the device thread has set the variable. Instead set it before cancellation. Even if the write() failed, the end result is command get possibly cancelled (even if cancellation came from external sources it doesn't matter much). It's worth to consider removing the backend processing thread for now. Signed-off-by: Marc-André Lureau Reviewed-by: Stefan Berger Signed-off-by: Stefan Berger --- hw/tpm/tpm_passthrough.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/hw/tpm/tpm_passthrough.c b/hw/tpm/tpm_passthrough.c index 788be38..73554aa 100644 --- a/hw/tpm/tpm_passthrough.c +++ b/hw/tpm/tpm_passthrough.c @@ -89,6 +89,7 @@ static int tpm_passthrough_unix_tx_bufs(TPMPassthruState *tpm_pt, bool is_selftest; const struct tpm_resp_hdr *hdr; + /* FIXME: protect shared variables or use other sync mechanism */ tpm_pt->tpm_op_canceled = false; tpm_pt->tpm_executing = true; *selftest_done = false; @@ -178,12 +179,11 @@ static void tpm_passthrough_cancel_cmd(TPMBackend *tb) */ if (tpm_pt->tpm_executing) { if (tpm_pt->cancel_fd >= 0) { + tpm_pt->tpm_op_canceled = true; n = write(tpm_pt->cancel_fd, "-", 1); if (n != 1) { error_report("Canceling TPM command failed: %s", strerror(errno)); - } else { - tpm_pt->tpm_op_canceled = true; } } else { error_report("Cannot cancel TPM command due to missing "