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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 30 Jul 2019 18:47:26 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x6UHlPWJ39715146 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 30 Jul 2019 17:47:25 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 187154C04A; Tue, 30 Jul 2019 17:47:25 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 60FDE4C059; Tue, 30 Jul 2019 17:47:24 +0000 (GMT) Received: from oc7455500831.ibm.com (unknown [9.145.144.206]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 30 Jul 2019 17:47:24 +0000 (GMT) To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Andrey Shinkevich , qemu-devel@nongnu.org, qemu-block@nongnu.org References: <1564502498-805893-1-git-send-email-andrey.shinkevich@virtuozzo.com> <1564502498-805893-4-git-send-email-andrey.shinkevich@virtuozzo.com> <7a78ef04-4120-20d9-d5f4-6572c5676344@redhat.com> From: Christian Borntraeger Openpgp: preference=signencrypt Autocrypt: addr=borntraeger@de.ibm.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 19073017-0012-0000-0000-00000337B25F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19073017-0013-0000-0000-0000217158B5 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-07-30_08:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound 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=8.0.1-1906280000 definitions=main-1907300187 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by mx0a-001b2d01.pphosted.com id x6UHmXrF043938 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 148.163.156.1 Subject: Re: [Qemu-devel] [PATCH 3/3] i386/kvm: initialize struct at full before ioctl call X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: vsementsov@virtuozzo.com, berto@igalia.com, ehabkost@redhat.com, kvm@vger.kernel.org, mtosatti@redhat.com, mdroth@linux.vnet.ibm.com, armbru@redhat.com, pbonzini@redhat.com, den@openvz.org, rth@twiddle.net Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 30.07.19 19:14, Philippe Mathieu-Daud=C3=A9 wrote: > On 7/30/19 7:05 PM, Christian Borntraeger wrote: >> On 30.07.19 18:44, Philippe Mathieu-Daud=C3=A9 wrote: >>> On 7/30/19 6:01 PM, Andrey Shinkevich wrote: >>>> Not the whole structure is initialized before passing it to the KVM. >>>> Reduce the number of Valgrind reports. >>>> >>>> Signed-off-by: Andrey Shinkevich >>>> --- >>>> target/i386/kvm.c | 3 +++ >>>> 1 file changed, 3 insertions(+) >>>> >>>> diff --git a/target/i386/kvm.c b/target/i386/kvm.c >>>> index dbbb137..ed57e31 100644 >>>> --- a/target/i386/kvm.c >>>> +++ b/target/i386/kvm.c >>>> @@ -190,6 +190,7 @@ static int kvm_get_tsc(CPUState *cs) >>>> return 0; >>>> } >>>> =20 >>>> + memset(&msr_data, 0, sizeof(msr_data)); >>> >>> I wonder the overhead of this one... >> >> Cant we use designated initializers like in >> >> commit bdfc8480c50a53d91aa9a513d23a84de0d5fbc86 >> Author: Christian Borntraeger >> AuthorDate: Thu Oct 30 09:23:41 2014 +0100 >> Commit: Paolo Bonzini >> CommitDate: Mon Dec 15 12:21:01 2014 +0100 >> >> valgrind/i386: avoid false positives on KVM_SET_XCRS ioctl >> >> and others? >=20 > Is the compiler smart enough to figure out it doesn't need to zeroes in > case env->tsc_valid is true and the function returns? Good question, we would need to double check with objdump.