Received: by 2002:a25:7ec1:0:0:0:0:0 with SMTP id z184csp7243517ybc; Thu, 28 Nov 2019 13:47:52 -0800 (PST) X-Google-Smtp-Source: APXvYqwqeaL8+xJrfBVLsef77EdXUiJnDViUt05jHSRMzX5QveGhKzC3vJMlhnDVBg/GgpZ72Z8+ X-Received: by 2002:a05:6402:311b:: with SMTP id dc27mr17700988edb.106.1574977672368; Thu, 28 Nov 2019 13:47:52 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1574977672; cv=none; d=google.com; s=arc-20160816; b=LtlOjEX0uKoo1WEUclDlQxaXAR+bxOu9zfQD0P74wUjv8kpfHYgAYgF3VMoAQ6LAsy 4Skpvw5kmDjgBtqFomJrD7a+dDi42QUd+JK0xwDbVRLt99xG6irgB/swKATLqtZSw5/K UQqtwOc/Mr42jDcrB5EHJb/sCq+dCe7B0gAWjzUyD3fr2jFG/zsWSpIHNk5SRsqJM1YO LJP/9xXHvZ2pTKWzbzQ4i0CXBbjzKnhUmaaNX0t82Fi9fJudGcU8LPb8kAAUOx+VDAAG +W6L4EDHzKL9iceLt8tRVnKVU3sE7vfZNlWqlaLPN05SiJHm8QN2G4/1ATVWozfAuFnT Yisw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-language :content-transfer-encoding:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:from:references:cc:to:subject:dkim-signature; bh=6XI4go+lb9shS5sonxMMGanusVftbZ4ONKKqMMScI5Q=; b=hWfiAayvOtf7nXjeyvTngBXEMhCkj5zucRx87OElvUzbp+OxLSNc1yB+yIozCQ6H8i egEeBfMaGJs4lB8S7V+TKGyDfuK8G2YZSYzgmBuJ0swtoC4KWkzryZnx0ktyZMhiyeej u9pUePf0aaQMqAdrVlADcI0P0599ppE0kiwHSX+8Tn2m99oeho6L/hU83f7fM63aA9Wf eQVO5syOV7bh8Y2W1S5hhtHggHO6crOvoqI/mpDo1kjyQqlQMSXHFtjdAKb3MKQTBioM 8QBbUX3J8DFujmYpWuLtWp4vLxkVyIvFr4xsuhOJUqLKqguYleCWDfPyrfNFIi+t4O1T 7JLw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2019-08-05 header.b=pJvQnCW1; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id dm19si5923693edb.214.2019.11.28.13.47.28; Thu, 28 Nov 2019 13:47:52 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2019-08-05 header.b=pJvQnCW1; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726721AbfK1VqL (ORCPT + 99 others); Thu, 28 Nov 2019 16:46:11 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:54378 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726558AbfK1VqL (ORCPT ); Thu, 28 Nov 2019 16:46:11 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xASLYDh9031956; Thu, 28 Nov 2019 21:38:21 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2019-08-05; bh=6XI4go+lb9shS5sonxMMGanusVftbZ4ONKKqMMScI5Q=; b=pJvQnCW19zjfJNwgHAxvfq8Nx8U9li8CBnYcaAB9ozBNszoJ3S/Olk0QPLzrvNh37dTA aJHWnn2+vW85sgb9/PuZwqzg7fpIC7XfXYBYJfBqBAxnU/fkRimp+HXCveicgn5syRtR l5uawUvQLs/xTWLOHEGcD3XWH0UnGinZpZOnWRyN+ivFFy8U9LC3sdnZdu/xf4aqwvyJ l5toovQJDS8lxWWcn/etzXxMN89x3sS2xr02DWLipbbVZl/CvzGZtUV113KwidPoXKzc peiVSD8BdaiPloLpamr/LBRXsuLAoZnWl8AYnVvFqAgUgpj6Oywd0G80R7Ot8mkSvefg nQ== Received: from aserp3020.oracle.com (aserp3020.oracle.com [141.146.126.70]) by userp2120.oracle.com with ESMTP id 2wewdrn34h-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Nov 2019 21:38:21 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xASLcIGq050314; Thu, 28 Nov 2019 21:38:21 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 2wjh0kme7v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Nov 2019 21:38:18 +0000 Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id xASLbq47029213; Thu, 28 Nov 2019 21:37:52 GMT Received: from bostrovs-us.us.oracle.com (/10.152.32.65) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Nov 2019 13:37:52 -0800 Subject: Re: [PATCH v2] xen/events: remove event handling recursion detection To: Juergen Gross , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Stefano Stabellini References: <20191128084545.13831-1-jgross@suse.com> From: Boris Ostrovsky Autocrypt: addr=boris.ostrovsky@oracle.com; prefer-encrypt=mutual; keydata= mQINBFH8CgsBEAC0KiOi9siOvlXatK2xX99e/J3OvApoYWjieVQ9232Eb7GzCWrItCzP8FUV PQg8rMsSd0OzIvvjbEAvaWLlbs8wa3MtVLysHY/DfqRK9Zvr/RgrsYC6ukOB7igy2PGqZd+M MDnSmVzik0sPvB6xPV7QyFsykEgpnHbvdZAUy/vyys8xgT0PVYR5hyvhyf6VIfGuvqIsvJw5 C8+P71CHI+U/IhsKrLrsiYHpAhQkw+Zvyeml6XSi5w4LXDbF+3oholKYCkPwxmGdK8MUIdkM d7iYdKqiP4W6FKQou/lC3jvOceGupEoDV9botSWEIIlKdtm6C4GfL45RD8V4B9iy24JHPlom woVWc0xBZboQguhauQqrBFooHO3roEeM1pxXjLUbDtH4t3SAI3gt4dpSyT3EvzhyNQVVIxj2 FXnIChrYxR6S0ijSqUKO0cAduenhBrpYbz9qFcB/GyxD+ZWY7OgQKHUZMWapx5bHGQ8bUZz2 SfjZwK+GETGhfkvNMf6zXbZkDq4kKB/ywaKvVPodS1Poa44+B9sxbUp1jMfFtlOJ3AYB0WDS Op3d7F2ry20CIf1Ifh0nIxkQPkTX7aX5rI92oZeu5u038dHUu/dO2EcuCjl1eDMGm5PLHDSP 0QUw5xzk1Y8MG1JQ56PtqReO33inBXG63yTIikJmUXFTw6lLJwARAQABtDNCb3JpcyBPc3Ry b3Zza3kgKFdvcmspIDxib3Jpcy5vc3Ryb3Zza3lAb3JhY2xlLmNvbT6JAjgEEwECACIFAlH8 CgsCGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEIredpCGysGyasEP/j5xApopUf4g 9Fl3UxZuBx+oduuw3JHqgbGZ2siA3EA4bKwtKq8eT7ekpApn4c0HA8TWTDtgZtLSV5IdH+9z JimBDrhLkDI3Zsx2CafL4pMJvpUavhc5mEU8myp4dWCuIylHiWG65agvUeFZYK4P33fGqoaS VGx3tsQIAr7MsQxilMfRiTEoYH0WWthhE0YVQzV6kx4wj4yLGYPPBtFqnrapKKC8yFTpgjaK jImqWhU9CSUAXdNEs/oKVR1XlkDpMCFDl88vKAuJwugnixjbPFTVPyoC7+4Bm/FnL3iwlJVE qIGQRspt09r+datFzPqSbp5Fo/9m4JSvgtPp2X2+gIGgLPWp2ft1NXHHVWP19sPgEsEJXSr9 tskM8ScxEkqAUuDs6+x/ISX8wa5Pvmo65drN+JWA8EqKOHQG6LUsUdJolFM2i4Z0k40BnFU/ kjTARjrXW94LwokVy4x+ZYgImrnKWeKac6fMfMwH2aKpCQLlVxdO4qvJkv92SzZz4538az1T m+3ekJAimou89cXwXHCFb5WqJcyjDfdQF857vTn1z4qu7udYCuuV/4xDEhslUq1+GcNDjAhB nNYPzD+SvhWEsrjuXv+fDONdJtmLUpKs4Jtak3smGGhZsqpcNv8nQzUGDQZjuCSmDqW8vn2o hWwveNeRTkxh+2x1Qb3GT46uuQINBFH8CgsBEADGC/yx5ctcLQlB9hbq7KNqCDyZNoYu1HAB Hal3MuxPfoGKObEktawQPQaSTB5vNlDxKihezLnlT/PKjcXC2R1OjSDinlu5XNGc6mnky03q yymUPyiMtWhBBftezTRxWRslPaFWlg/h/Y1iDuOcklhpr7K1h1jRPCrf1yIoxbIpDbffnuyz kuto4AahRvBU4Js4sU7f/btU+h+e0AcLVzIhTVPIz7PM+Gk2LNzZ3/on4dnEc/qd+ZZFlOQ4 KDN/hPqlwA/YJsKzAPX51L6Vv344pqTm6Z0f9M7YALB/11FO2nBB7zw7HAUYqJeHutCwxm7i BDNt0g9fhviNcJzagqJ1R7aPjtjBoYvKkbwNu5sWDpQ4idnsnck4YT6ctzN4I+6lfkU8zMzC gM2R4qqUXmxFIS4Bee+gnJi0Pc3KcBYBZsDK44FtM//5Cp9DrxRQOh19kNHBlxkmEb8kL/pw XIDcEq8MXzPBbxwHKJ3QRWRe5jPNpf8HCjnZz0XyJV0/4M1JvOua7IZftOttQ6KnM4m6WNIZ 2ydg7dBhDa6iv1oKdL7wdp/rCulVWn8R7+3cRK95SnWiJ0qKDlMbIN8oGMhHdin8cSRYdmHK kTnvSGJNlkis5a+048o0C6jI3LozQYD/W9wq7MvgChgVQw1iEOB4u/3FXDEGulRVko6xCBU4 SQARAQABiQIfBBgBAgAJBQJR/AoLAhsMAAoJEIredpCGysGyfvMQAIywR6jTqix6/fL0Ip8G jpt3uk//QNxGJE3ZkUNLX6N786vnEJvc1beCu6EwqD1ezG9fJKMl7F3SEgpYaiKEcHfoKGdh 30B3Hsq44vOoxR6zxw2B/giADjhmWTP5tWQ9548N4VhIZMYQMQCkdqaueSL+8asp8tBNP+TJ PAIIANYvJaD8xA7sYUXGTzOXDh2THWSvmEWWmzok8er/u6ZKdS1YmZkUy8cfzrll/9hiGCTj u3qcaOM6i/m4hqtvsI1cOORMVwjJF4+IkC5ZBoeRs/xW5zIBdSUoC8L+OCyj5JETWTt40+lu qoqAF/AEGsNZTrwHJYu9rbHH260C0KYCNqmxDdcROUqIzJdzDKOrDmebkEVnxVeLJBIhYZUd t3Iq9hdjpU50TA6sQ3mZxzBdfRgg+vaj2DsJqI5Xla9QGKD+xNT6v14cZuIMZzO7w0DoojM4 ByrabFsOQxGvE0w9Dch2BDSI2Xyk1zjPKxG1VNBQVx3flH37QDWpL2zlJikW29Ws86PHdthh Fm5PY8YtX576DchSP6qJC57/eAAe/9ztZdVAdesQwGb9hZHJc75B+VNm4xrh/PJO6c1THqdQ 19WVJ+7rDx3PhVncGlbAOiiiE3NOFPJ1OQYxPKtpBUukAlOTnkKE6QcA4zckFepUkfmBV1wM Jg6OxFYd01z+a+oL Message-ID: Date: Thu, 28 Nov 2019 16:37:27 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191128084545.13831-1-jgross@suse.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9455 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911280189 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9455 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911280188 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/28/19 3:45 AM, Juergen Gross wrote: > - > static void __xen_evtchn_do_upcall(void) > { > struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); > - int cpu = get_cpu(); > - unsigned count; > + int cpu = smp_processor_id(); > > do { > vcpu_info->evtchn_upcall_pending = 0; > > - if (__this_cpu_inc_return(xed_nesting_count) - 1) > - goto out; > - > xen_evtchn_handle_events(cpu); > > BUG_ON(!irqs_disabled()); > > - count = __this_cpu_read(xed_nesting_count); > - __this_cpu_write(xed_nesting_count, 0); > - } while (count != 1 || vcpu_info->evtchn_upcall_pending); > - > -out: > + rmb(); /* Hypervisor can set upcall pending. */ virt_rmb() perhaps then? -boris > > - put_cpu(); > + } while (vcpu_info->evtchn_upcall_pending); > } > > void xen_evtchn_do_upcall(struct pt_regs *regs)