[{"id":1771999,"web_url":"http://patchwork.ozlabs.org/comment/1771999/","msgid":"<20170920150006.GB1859@perard.uk.xensource.com>","list_archive_url":null,"date":"2017-09-20T15:00:06","subject":"Re: [Qemu-devel] [PATCH 2/2] xen: dont try setting max grants\n\tmultiple times","submitter":{"id":4759,"url":"http://patchwork.ozlabs.org/api/people/4759/","name":"Anthony PERARD","email":"anthony.perard@citrix.com"},"content":"On Tue, Sep 19, 2017 at 01:50:55PM +0200, Juergen Gross wrote:\n> Trying to call xengnttab_set_max_grants() with the same file handle\n> might fail on some kernels, as this operation is allowed only once.\n> \n> This is a problem for the qdisk backend as blk_connect() can be\n> called multiple times for a domain, e.g. in case grub-xen is being\n> used to boot it.\n> \n> So instead of letting the generic backend code open the gnttab device\n> do it in blk_connect() and close it again in blk_disconnect.\n> \n> Signed-off-by: Juergen Gross \n> ---\n> hw/block/xen_disk.c | 12 +++++++++++-\n> 1 file changed, 11 insertions(+), 1 deletion(-)\n> \n> diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c\n> index 6632746250..7cff8863cb 100644\n> --- a/hw/block/xen_disk.c\n> +++ b/hw/block/xen_disk.c\n> @@ -1220,6 +1220,12 @@ static int blk_connect(struct XenDevice *xendev)\n> /* Add on the number needed for the ring pages */\n> max_grants += blkdev->nr_ring_ref;\n> \n> + blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0);\n> + if (blkdev->xendev.gnttabdev == NULL) {\n> + xen_pv_printf(xendev, 0, \"xengnttab_open failed: %s\\n\",\n> + strerror(errno));\n> + return -1;\n> + }\n> if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {\n> xen_pv_printf(xendev, 0, \"xengnttab_set_max_grants failed: %s\\n\",\n> strerror(errno));\n> @@ -1327,6 +1333,11 @@ static void blk_disconnect(struct XenDevice *xendev)\n> }\n> blkdev->feature_persistent = false;\n> }\n> +\n> + if (blkdev->xendev.gnttabdev) {\n> + xengnttab_close(blkdev->xendev.gnttabdev);\n> + blkdev->xendev.gnttabdev = NULL;\n> + }\n\nI think blk_disconnect needs to be called from blk_free in case where\nthe gnttabdev is not closed (like it is done when blk or the sring are\nnot cleared, in blk_free).\n\n> }\n\n> static int blk_free(struct XenDevice *xendev)\n> @@ -1363,7 +1374,6 @@ static void blk_event(struct XenDevice *xendev)\n> \n> struct XenDevOps xen_blkdev_ops = {\n> .size = sizeof(struct XenBlkDev),\n> - .flags = DEVOPS_FLAG_NEED_GNTDEV,\n> .alloc = blk_alloc,\n> .init = blk_init,\n> .initialise = blk_connect,\n> -- \n> 2.12.3\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":"ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; 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Wed, 20 Sep 2017 11:00:30 -0400"],"X-IronPort-AV":"E=Sophos;i=\"5.42,421,1500940800\"; d=\"scan'208\";a=\"448549563\"","Date":"Wed, 20 Sep 2017 16:00:06 +0100","From":"Anthony PERARD ","To":"Juergen Gross ","Message-ID":"<20170920150006.GB1859@perard.uk.xensource.com>","References":"<20170919115055.19278-1-jgross@suse.com>\n\t<20170919115055.19278-3-jgross@suse.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Disposition":"inline","In-Reply-To":"<20170919115055.19278-3-jgross@suse.com>","User-Agent":"Mutt/1.9.0 (2017-09-02)","X-detected-operating-system":"by eggs.gnu.org: Genre and OS details not\n\trecognized.","X-Received-From":"66.165.176.63","Subject":"Re: [Qemu-devel] [PATCH 2/2] xen: dont try setting max grants\n\tmultiple times","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"xen-devel@lists.xenproject.org, sstabellini@kernel.org,\n\tqemu-devel@nongnu.org, kraxel@redhat.com","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}},{"id":1773528,"web_url":"http://patchwork.ozlabs.org/comment/1773528/","msgid":"<912fbfb9-59b9-fceb-237f-3b201f6eaa38@suse.com>","list_archive_url":null,"date":"2017-09-22T12:03:47","subject":"Re: [Qemu-devel] [Xen-devel] [PATCH 2/2] xen: dont try setting max\n\tgrants multiple times","submitter":{"id":64874,"url":"http://patchwork.ozlabs.org/api/people/64874/","name":"Jürgen Groß","email":"jgross@suse.com"},"content":"On 20/09/17 17:00, Anthony PERARD wrote:\n> On Tue, Sep 19, 2017 at 01:50:55PM +0200, Juergen Gross wrote:\n>> Trying to call xengnttab_set_max_grants() with the same file handle\n>> might fail on some kernels, as this operation is allowed only once.\n>>\n>> This is a problem for the qdisk backend as blk_connect() can be\n>> called multiple times for a domain, e.g. in case grub-xen is being\n>> used to boot it.\n>>\n>> So instead of letting the generic backend code open the gnttab device\n>> do it in blk_connect() and close it again in blk_disconnect.\n>>\n>> Signed-off-by: Juergen Gross \n>> ---\n>> hw/block/xen_disk.c | 12 +++++++++++-\n>> 1 file changed, 11 insertions(+), 1 deletion(-)\n>>\n>> diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c\n>> index 6632746250..7cff8863cb 100644\n>> --- a/hw/block/xen_disk.c\n>> +++ b/hw/block/xen_disk.c\n>> @@ -1220,6 +1220,12 @@ static int blk_connect(struct XenDevice *xendev)\n>> /* Add on the number needed for the ring pages */\n>> max_grants += blkdev->nr_ring_ref;\n>> \n>> + blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0);\n>> + if (blkdev->xendev.gnttabdev == NULL) {\n>> + xen_pv_printf(xendev, 0, \"xengnttab_open failed: %s\\n\",\n>> + strerror(errno));\n>> + return -1;\n>> + }\n>> if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {\n>> xen_pv_printf(xendev, 0, \"xengnttab_set_max_grants failed: %s\\n\",\n>> strerror(errno));\n>> @@ -1327,6 +1333,11 @@ static void blk_disconnect(struct XenDevice *xendev)\n>> }\n>> blkdev->feature_persistent = false;\n>> }\n>> +\n>> + if (blkdev->xendev.gnttabdev) {\n>> + xengnttab_close(blkdev->xendev.gnttabdev);\n>> + blkdev->xendev.gnttabdev = NULL;\n>> + }\n> \n> I think blk_disconnect needs to be called from blk_free in case where\n> the gnttabdev is not closed (like it is done when blk or the sring are\n> not cleared, in blk_free).\n\nRight. Just calling it always from blk_free() should do the job.\n\nBTW: in practice this wouldn't be necessary as xen_pv_del_xendev()\nalready does the close, but this is just good luck. Better closing it\nvia blk_free() in case xen_pv_del_xendev() adds a test for\nDEVOPS_FLAG_NEED_GNTDEV.\n\n\nThanks,\n\nJuergen","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":"ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","Received":["from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xzBwt5ytCz9sPk\n\tfor ;\n\tFri, 22 Sep 2017 22:04:24 +1000 (AEST)","from localhost ([::1]:58475 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dvMgv-0006AT-Rv\n\tfor incoming@patchwork.ozlabs.org; Fri, 22 Sep 2017 08:04:21 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:46647)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dvMgW-0006AE-Fm\n\tfor qemu-devel@nongnu.org; Fri, 22 Sep 2017 08:04:00 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dvMgQ-0004dn-O1\n\tfor qemu-devel@nongnu.org; Fri, 22 Sep 2017 08:03:56 -0400","from mx2.suse.de ([195.135.220.15]:60804 helo=mx1.suse.de)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from ) id 1dvMgQ-0004c2-Hb\n\tfor qemu-devel@nongnu.org; Fri, 22 Sep 2017 08:03:50 -0400","from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254])\n\tby mx1.suse.de (Postfix) with ESMTP id 18F6EABF4;\n\tFri, 22 Sep 2017 12:03:48 +0000 (UTC)"],"X-Virus-Scanned":"by amavisd-new at test-mx.suse.de","To":"Anthony PERARD ","References":"<20170919115055.19278-1-jgross@suse.com>\n\t<20170919115055.19278-3-jgross@suse.com>\n\t<20170920150006.GB1859@perard.uk.xensource.com>","From":"Juergen Gross ","Message-ID":"<912fbfb9-59b9-fceb-237f-3b201f6eaa38@suse.com>","Date":"Fri, 22 Sep 2017 14:03:47 +0200","User-Agent":"Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101\n\tThunderbird/52.3.0","MIME-Version":"1.0","In-Reply-To":"<20170920150006.GB1859@perard.uk.xensource.com>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-US","Content-Transfer-Encoding":"7bit","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x (no\n\ttimestamps) [generic] [fuzzy]","X-Received-From":"195.135.220.15","Subject":"Re: [Qemu-devel] [Xen-devel] [PATCH 2/2] xen: dont try setting max\n\tgrants multiple times","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"xen-devel@lists.xenproject.org, sstabellini@kernel.org,\n\tqemu-devel@nongnu.org, kraxel@redhat.com","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}}]