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Fri, 6 Feb 2026 10:33:23 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 907EB2004B; Fri, 6 Feb 2026 10:33:23 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4A3F220043; Fri, 6 Feb 2026 10:33:22 +0000 (GMT) Received: from p-imbrenda (unknown [9.111.36.153]) by smtpav04.fra02v.mail.ibm.com (Postfix) with SMTP; Fri, 6 Feb 2026 10:33:22 +0000 (GMT) Date: Fri, 6 Feb 2026 11:33:19 +0100 From: Claudio Imbrenda To: Arnd Bergmann Cc: Paolo Bonzini , Heiko Carstens , Arnd Bergmann , Oliver Upton , Sean Christopherson , Anup Patel , Binbin Wu , Marc Zyngier , Jiaqi Yan , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: s390: add explicit padding to struct kvm_s390_keyop Message-ID: <20260206113319.49a600f2@p-imbrenda> In-Reply-To: <20260206091751.3973615-1-arnd@kernel.org> References: <20260206091751.3973615-1-arnd@kernel.org> Organization: IBM X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=UdxciaSN c=1 sm=1 tr=0 ts=6985c376 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=kj9zAlcOel0A:10 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=H89wNOMt5Vhrhf4zh90A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-GUID: ViOT9jI8OiAUdCB-UQ843pT_KR-3y4Nk X-Proofpoint-ORIG-GUID: OwnPD8PrGShkfWHpCpWinvwFVk4RXQBt X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjA2MDA3MCBTYWx0ZWRfXz4KQpdSNmR2O pfDu9K/C/oX9FRewe1w61N2/YkTltW7FaNNOJIRkdOil5HDzsZL48VH3PWEWkR6bHjuEKKdpk4Q aswJlpZJ6YDgR/GUIbHpDnFXqMCTo5fxnBqt2mDL95s43sXwKxOScmiZFuVSbIwbelWGXmeIRUA Q+mn43KbAY8pfwJMexz7Des9hh4XzEPPQW4jysGhGurswLVM5AchnWCte8HzL2AhIp5WHbwRbDd oCsIOV9VFU8yZKOvPAbj7swVxqWmP7lqwz6koSJz7eVhz9cAheM1WDm3uc8dyZLyD4nA6zWZ10Z MIASCbMtNHbNxKkz9dHN5AUuoKGYwfIrHH18AV4RO2ioqGST4rS/FiQXeoiAxf3q8z1ilIY9roa uK5oZgJUoz24JcM/zx3xswlk+hLGPhXosEwfNlR8Pd96shXFTGYqq2e8uyyoe/aSWb1GAB2q0p+ K07qquazuuvVIgY26hg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-06_03,2026-02-05_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 impostorscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1011 bulkscore=0 spamscore=0 phishscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2602060070 On Fri, 6 Feb 2026 10:17:30 +0100 Arnd Bergmann wrote: > From: Arnd Bergmann > > The newly added structure causes a warning about implied padding: > > ./usr/include/linux/kvm.h:1247:1: error: padding struct size to alignment boundary with 6 bytes [-Werror=padded] > > The padding can lead to leaking kernel data and ABI incompatibilies > when used on x86. Neither of these is a problem in this specific > patch, but it's best to avoid it and use explicit padding fields > in general. > > Fixes: 0ee4ddc1647b ("KVM: s390: Storage key manipulation IOCTL") > Signed-off-by: Arnd Bergmann Reviewed-by: Claudio Imbrenda > --- > I have a long series to add annotations to all existing structures, > but that will take a while. For now, I'm sending fixes when new > instances show up in linux-next. > --- > include/uapi/linux/kvm.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index a68b1741045c..1225fbd017e5 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -1255,6 +1255,7 @@ struct kvm_s390_keyop { > __u64 guest_addr; > __u8 key; > __u8 operation; > + __u8 pad[6]; > }; > > /*