[{"id":1768926,"web_url":"http://patchwork.ozlabs.org/comment/1768926/","msgid":"<20170915005415.GB5250@umbus.fritz.box>","list_archive_url":null,"date":"2017-09-15T00:54:15","subject":"Re: [Qemu-devel] [PATCH 1/3] kvm: check KVM_CAP_SYNC_MMU with\n\tkvm_vm_check_extension()","submitter":{"id":47,"url":"http://patchwork.ozlabs.org/api/people/47/","name":"David Gibson","email":"david@gibson.dropbear.id.au"},"content":"On Thu, Sep 14, 2017 at 09:25:22PM +0200, Greg Kurz wrote:\n> On a server-class ppc host, this capability depends on the KVM type,\n> ie, HV or PR. If both KVM are present in the kernel, we will always\n> get the HV specific value, even if we explicitely requested PR on\n> the command line.\n> \n> This can have an impact if we're using hugepages or a balloon device.\n> \n> Since we've already created the VM at the time any user calls\n> kvm_has_sync_mmu(), switching to kvm_vm_check_extension() is\n> enough to fix any potential issue.\n> \n> It is okay for the other archs that also implement KVM_CAP_SYNC_MMU,\n> ie, mips, s390, x86 and arm, because they don't depend on the VM being\n> created or not.\n> \n> Signed-off-by: Greg Kurz \n\nReviewed-by: David Gibson \n\n> ---\n> accel/kvm/kvm-all.c | 2 +-\n> 1 file changed, 1 insertion(+), 1 deletion(-)\n> \n> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c\n> index f85553a85194..323c567cfb68 100644\n> --- a/accel/kvm/kvm-all.c\n> +++ b/accel/kvm/kvm-all.c\n> @@ -2234,7 +2234,7 @@ int kvm_device_access(int fd, int group, uint64_t attr,\n> /* Return 1 on success, 0 on failure */\n> int kvm_has_sync_mmu(void)\n> {\n> - return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);\n> + return kvm_vm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);\n> }\n> \n> int kvm_has_vcpu_events(void)\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; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=gibson.dropbear.id.au\n\theader.i=@gibson.dropbear.id.au header.b=\"EG+rdd8P\"; \n\tdkim-atps=neutral"],"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 3xtgBj6KLtz9sPr\n\tfor ;\n\tFri, 15 Sep 2017 13:00:45 +1000 (AEST)","from localhost ([::1]:50876 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dsgrz-0005XB-Vu\n\tfor incoming@patchwork.ozlabs.org; Thu, 14 Sep 2017 23:00:44 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:46618)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dsgrC-0005WN-L5\n\tfor qemu-devel@nongnu.org; Thu, 14 Sep 2017 22:59:55 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dsgrB-0002ZL-Cy\n\tfor qemu-devel@nongnu.org; Thu, 14 Sep 2017 22:59:54 -0400","from ozlabs.org ([2401:3900:2:1::2]:60263)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from )\n\tid 1dsgrB-0002Yh-0t; Thu, 14 Sep 2017 22:59:53 -0400","by ozlabs.org (Postfix, from userid 1007)\n\tid 3xtg9d49T3z9sPr; Fri, 15 Sep 2017 12:59:49 +1000 (AEST)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/simple;\n\td=gibson.dropbear.id.au; s=201602; t=1505444389;\n\tbh=ebemSY2OXTgx4GgGoKr5t+XOP2k19gDq0xlunGbGyag=;\n\th=Date:From:To:Cc:Subject:References:In-Reply-To:From;\n\tb=EG+rdd8PzKhene1BCZJSVvf5L44vYiG4dTlmSDrzL+GABVrRQmsVFilJXsDTqQH1T\n\t/CNV29GEcimrQN3NamDeybWjGsYI6rIOh3I6zixV8cQvXdLTz12dMxHGC8j3EUN5hC\n\thpkhYXHJmkW/6P5rGH1co/lwfRRtI+n1lX7VxnqQ=","Date":"Fri, 15 Sep 2017 10:54:15 +1000","From":"David Gibson ","To":"Greg Kurz ","Message-ID":"<20170915005415.GB5250@umbus.fritz.box>","References":"<150541711102.1616.2690784964841960181.stgit@bahia.lan>\n\t<150541712226.1616.17581342887936984948.stgit@bahia.lan>","MIME-Version":"1.0","Content-Type":"multipart/signed; micalg=pgp-sha256;\n\tprotocol=\"application/pgp-signature\"; boundary=\"E39vaYmALEf/7YXx\"","Content-Disposition":"inline","In-Reply-To":"<150541712226.1616.17581342887936984948.stgit@bahia.lan>","User-Agent":"Mutt/1.8.3 (2017-05-23)","X-detected-operating-system":"by eggs.gnu.org: Genre and OS details not\n\trecognized.","X-Received-From":"2401:3900:2:1::2","Subject":"Re: [Qemu-devel] [PATCH 1/3] kvm: check KVM_CAP_SYNC_MMU with\n\tkvm_vm_check_extension()","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":"Paolo Bonzini , Thomas Huth ,\n\tqemu-ppc@nongnu.org, qemu-devel@nongnu.org,\n\tSam Bobroff ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}},{"id":1768948,"web_url":"http://patchwork.ozlabs.org/comment/1768948/","msgid":"","list_archive_url":null,"date":"2017-09-15T05:32:10","subject":"Re: [Qemu-devel] [PATCH 1/3] kvm: check KVM_CAP_SYNC_MMU with\n\tkvm_vm_check_extension()","submitter":{"id":66152,"url":"http://patchwork.ozlabs.org/api/people/66152/","name":"Thomas Huth","email":"thuth@redhat.com"},"content":"On 14.09.2017 21:25, Greg Kurz wrote:\n> On a server-class ppc host, this capability depends on the KVM type,\n> ie, HV or PR. If both KVM are present in the kernel, we will always\n> get the HV specific value, even if we explicitely requested PR on\n> the command line.\n> \n> This can have an impact if we're using hugepages or a balloon device.\n> \n> Since we've already created the VM at the time any user calls\n> kvm_has_sync_mmu(), switching to kvm_vm_check_extension() is\n> enough to fix any potential issue.\n> \n> It is okay for the other archs that also implement KVM_CAP_SYNC_MMU,\n> ie, mips, s390, x86 and arm, because they don't depend on the VM being\n> created or not.\n> \n> Signed-off-by: Greg Kurz \n> ---\n> accel/kvm/kvm-all.c | 2 +-\n> 1 file changed, 1 insertion(+), 1 deletion(-)\n> \n> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c\n> index f85553a85194..323c567cfb68 100644\n> --- a/accel/kvm/kvm-all.c\n> +++ b/accel/kvm/kvm-all.c\n> @@ -2234,7 +2234,7 @@ int kvm_device_access(int fd, int group, uint64_t attr,\n> /* Return 1 on success, 0 on failure */\n> int kvm_has_sync_mmu(void)\n> {\n> - return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);\n> + return kvm_vm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);\n> }\n\nReviewed-by: Thomas Huth \n\n... but while you're at it, maybe it would be better to use a bool\nvariable for the state of this extension, too, and only check for the\nextension one time at the end of kvm_init() ? kvm_has_sync_mmu() is\napparently used multiple times in other source files, so we might be\nable to save some cycles by doing the syscall only once?\n\n Thomas","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=)","ext-mx03.extmail.prod.ext.phx2.redhat.com;\n\tdmarc=none (p=none dis=none) header.from=redhat.com","ext-mx03.extmail.prod.ext.phx2.redhat.com;\n\tspf=fail smtp.mailfrom=thuth@redhat.com"],"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 3xtkZ44ccTz9sBZ\n\tfor ;\n\tFri, 15 Sep 2017 15:32:42 +1000 (AEST)","from localhost ([::1]:51379 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dsjF2-0004bD-AF\n\tfor incoming@patchwork.ozlabs.org; Fri, 15 Sep 2017 01:32:40 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:47996)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dsjEg-0004ao-W5\n\tfor qemu-devel@nongnu.org; Fri, 15 Sep 2017 01:32:19 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dsjEd-0007J1-0S\n\tfor qemu-devel@nongnu.org; Fri, 15 Sep 2017 01:32:18 -0400","from mx1.redhat.com ([209.132.183.28]:32872)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from )\n\tid 1dsjEc-0007ID-QR; Fri, 15 Sep 2017 01:32:14 -0400","from smtp.corp.redhat.com\n\t(int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby mx1.redhat.com (Postfix) with ESMTPS id AFC3B83F40;\n\tFri, 15 Sep 2017 05:32:13 +0000 (UTC)","from [10.36.116.76] (ovpn-116-76.ams2.redhat.com [10.36.116.76])\n\tby smtp.corp.redhat.com (Postfix) with ESMTPS id 42DC27AA53;\n\tFri, 15 Sep 2017 05:32:12 +0000 (UTC)"],"DMARC-Filter":"OpenDMARC Filter v1.3.2 mx1.redhat.com AFC3B83F40","To":"Greg Kurz , qemu-devel@nongnu.org","References":"<150541711102.1616.2690784964841960181.stgit@bahia.lan>\n\t<150541712226.1616.17581342887936984948.stgit@bahia.lan>","From":"Thomas Huth ","Message-ID":"","Date":"Fri, 15 Sep 2017 07:32:10 +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":"<150541712226.1616.17581342887936984948.stgit@bahia.lan>","Content-Type":"text/plain; charset=utf-8","Content-Language":"en-US","Content-Transfer-Encoding":"7bit","X-Scanned-By":"MIMEDefang 2.79 on 10.5.11.13","X-Greylist":"Sender IP whitelisted, not delayed by milter-greylist-4.5.16\n\t(mx1.redhat.com [10.5.110.27]);\n\tFri, 15 Sep 2017 05:32:13 +0000 (UTC)","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic]\n\t[fuzzy]","X-Received-From":"209.132.183.28","Subject":"Re: [Qemu-devel] [PATCH 1/3] kvm: check KVM_CAP_SYNC_MMU with\n\tkvm_vm_check_extension()","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":"Paolo Bonzini , qemu-ppc@nongnu.org,\n\tSam Bobroff ,\n\tDavid Gibson ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}},{"id":1769247,"web_url":"http://patchwork.ozlabs.org/comment/1769247/","msgid":"<20170915171432.7a5cb91a@bahia.lan>","list_archive_url":null,"date":"2017-09-15T15:14:32","subject":"Re: [Qemu-devel] [PATCH 1/3] kvm: check KVM_CAP_SYNC_MMU with\n\tkvm_vm_check_extension()","submitter":{"id":69178,"url":"http://patchwork.ozlabs.org/api/people/69178/","name":"Greg Kurz","email":"groug@kaod.org"},"content":"On Fri, 15 Sep 2017 07:32:10 +0200\nThomas Huth wrote:\n\n> On 14.09.2017 21:25, Greg Kurz wrote:\n> > On a server-class ppc host, this capability depends on the KVM type,\n> > ie, HV or PR. If both KVM are present in the kernel, we will always\n> > get the HV specific value, even if we explicitely requested PR on\n> > the command line.\n> > \n> > This can have an impact if we're using hugepages or a balloon device.\n> > \n> > Since we've already created the VM at the time any user calls\n> > kvm_has_sync_mmu(), switching to kvm_vm_check_extension() is\n> > enough to fix any potential issue.\n> > \n> > It is okay for the other archs that also implement KVM_CAP_SYNC_MMU,\n> > ie, mips, s390, x86 and arm, because they don't depend on the VM being\n> > created or not.\n> > \n> > Signed-off-by: Greg Kurz \n> > ---\n> > accel/kvm/kvm-all.c | 2 +-\n> > 1 file changed, 1 insertion(+), 1 deletion(-)\n> > \n> > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c\n> > index f85553a85194..323c567cfb68 100644\n> > --- a/accel/kvm/kvm-all.c\n> > +++ b/accel/kvm/kvm-all.c\n> > @@ -2234,7 +2234,7 @@ int kvm_device_access(int fd, int group, uint64_t attr,\n> > /* Return 1 on success, 0 on failure */\n> > int kvm_has_sync_mmu(void)\n> > {\n> > - return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);\n> > + return kvm_vm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);\n> > } \n> \n> Reviewed-by: Thomas Huth \n> \n> ... but while you're at it, maybe it would be better to use a bool\n> variable for the state of this extension, too, and only check for the\n> extension one time at the end of kvm_init() ? kvm_has_sync_mmu() is\n> apparently used multiple times in other source files, so we might be\n> able to save some cycles by doing the syscall only once?\n> \n> Thomas\n> \n> \n\nOops, I had overlooked your answer... yes it makes sense indeed.\n\nI'll post a v2 of this patch (not resending the whole series).\n\nCheers,\n\n--\nGreg","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 3xtzVD3jsNz9sPs\n\tfor ;\n\tSat, 16 Sep 2017 01:15:16 +1000 (AEST)","from localhost ([::1]:53770 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dssKo-0002p3-LL\n\tfor incoming@patchwork.ozlabs.org; Fri, 15 Sep 2017 11:15:14 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:47068)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dssKN-0002oM-P0\n\tfor qemu-devel@nongnu.org; Fri, 15 Sep 2017 11:14:48 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dssKI-0000Zt-Pt\n\tfor qemu-devel@nongnu.org; Fri, 15 Sep 2017 11:14:47 -0400","from 1.mo2.mail-out.ovh.net ([46.105.63.121]:36108)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from ) id 1dssKI-0000Z0-JK\n\tfor qemu-devel@nongnu.org; Fri, 15 Sep 2017 11:14:42 -0400","from player770.ha.ovh.net (b6.ovh.net [213.186.33.56])\n\tby mo2.mail-out.ovh.net (Postfix) with ESMTP id 147F1AC350\n\tfor ; Fri, 15 Sep 2017 17:14:40 +0200 (CEST)","from bahia.lan (gar31-1-82-66-74-139.fbx.proxad.net [82.66.74.139])\n\t(Authenticated sender: groug@kaod.org)\n\tby player770.ha.ovh.net (Postfix) with ESMTPSA id 09F533C006C;\n\tFri, 15 Sep 2017 17:14:33 +0200 (CEST)"],"Date":"Fri, 15 Sep 2017 17:14:32 +0200","From":"Greg Kurz ","To":"Thomas Huth ","Message-ID":"<20170915171432.7a5cb91a@bahia.lan>","In-Reply-To":"","References":"<150541711102.1616.2690784964841960181.stgit@bahia.lan>\n\t<150541712226.1616.17581342887936984948.stgit@bahia.lan>\n\t","X-Mailer":"Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu)","MIME-Version":"1.0","Content-Type":"multipart/signed; micalg=pgp-sha1;\n\tboundary=\"Sig_/Rwl_JvF7sr1JIlh66p2Kaqh\";\n\tprotocol=\"application/pgp-signature\"","X-Ovh-Tracer-Id":"17176728982946945330","X-VR-SPAMSTATE":"OK","X-VR-SPAMSCORE":"-100","X-VR-SPAMCAUSE":"gggruggvucftvghtrhhoucdtuddrfeelledrgeekgdekiecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic]\n\t[fuzzy]","X-Received-From":"46.105.63.121","Subject":"Re: [Qemu-devel] [PATCH 1/3] kvm: check KVM_CAP_SYNC_MMU with\n\tkvm_vm_check_extension()","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":"Paolo Bonzini , qemu-ppc@nongnu.org,\n\tqemu-devel@nongnu.org, Sam Bobroff ,\n\tDavid Gibson ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}}]