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[23.128.96.18]) by mx.google.com with ESMTP id gz17si1194787ejc.25.2021.03.05.02.54.36; Fri, 05 Mar 2021 02:54:58 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@suse.com header.s=susede1 header.b=b3d6Inoy; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=NONE dis=NONE) header.from=suse.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229672AbhCEKxe (ORCPT + 99 others); Fri, 5 Mar 2021 05:53:34 -0500 Received: from mx2.suse.de ([195.135.220.15]:60674 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229493AbhCEKx2 (ORCPT ); Fri, 5 Mar 2021 05:53:28 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1614941606; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=t9yhPDURsr1qBZgJ3eTwq5iF3yZRze/MqoqPnLfQxQg=; b=b3d6Inoy4CO1P5Iu4Pgi7Sllh2M+TW/Q+sz8yJT073httTuYXhL0owKskdvCbqMI5LAj1K 1mPZ0sHBrwgsMRGlmRsAzsZmzPWeWvFrir3JjKnWnezlPdebWzNnA8tFJoLp46lm6O4iwr dxYLVmL/drdmxxNTJcRHP+PnYRiR/3c= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B6388AEB3; Fri, 5 Mar 2021 10:53:26 +0000 (UTC) Subject: Re: [PATCH v3 2/8] xen/events: don't unmask an event channel when an eoi is pending To: Ross Lagerwall , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Boris Ostrovsky , Stefano Stabellini , stable@vger.kernel.org, Julien Grall References: <20210219154030.10892-1-jgross@suse.com> <20210219154030.10892-3-jgross@suse.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: Date: Fri, 5 Mar 2021 11:53:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vGgwMX0OVBhr9spvhVf2Y8thFVRPVW5Yi" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --vGgwMX0OVBhr9spvhVf2Y8thFVRPVW5Yi Content-Type: multipart/mixed; boundary="5IJGrGLpJ892MRBD4wVWZEDLWV7f7e1BF"; protected-headers="v1" From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= To: Ross Lagerwall , xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Boris Ostrovsky , Stefano Stabellini , stable@vger.kernel.org, Julien Grall Message-ID: Subject: Re: [PATCH v3 2/8] xen/events: don't unmask an event channel when an eoi is pending References: <20210219154030.10892-1-jgross@suse.com> <20210219154030.10892-3-jgross@suse.com> In-Reply-To: --5IJGrGLpJ892MRBD4wVWZEDLWV7f7e1BF Content-Type: multipart/mixed; boundary="------------E52438B6194F302B7C9C960C" Content-Language: en-US This is a multi-part message in MIME format. --------------E52438B6194F302B7C9C960C Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 23.02.21 10:26, Ross Lagerwall wrote: > On 2021-02-19 15:40, Juergen Gross wrote: >> An event channel should be kept masked when an eoi is pending for it. >> When being migrated to another cpu it might be unmasked, though. >> >> In order to avoid this keep three different flags for each event chann= el >> to be able to distinguish "normal" masking/unmasking from eoi related >> masking/unmasking and temporary masking. The event channel should only= >> be able to generate an interrupt if all flags are cleared. >> >> Cc: stable@vger.kernel.org >> Fixes: 54c9de89895e0a36047 ("xen/events: add a new late EOI evtchn fra= mework") >> Reported-by: Julien Grall >> Signed-off-by: Juergen Gross >=20 > I tested this patch series backported to a 4.19 kernel and found that > when doing a reboot loop of Windows with PV drivers, occasionally it wi= ll > end up in a state with some event channels pending and masked in dom0 > which breaks networking in the guest. >=20 > The issue seems to have been introduced with this patch, though at firs= t > glance it appears correct. I haven't yet looked into why it is happenin= g. > Have you seen anything like this with this patch? Sorry it took so long, but now I was able to look into this issue. I have managed to reproduce it with a pv Linux guest. I'm now adding some debug code to understand what is happening there. 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