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Tue, 4 Aug 2026 17:18:35 +0000 (GMT) Message-ID: Date: Tue, 4 Aug 2026 13:18:35 -0400 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/7] KVM: s390: Zero initialize irq in reinject_machine_check To: Christian Borntraeger , KVM Cc: Janosch Frank , David Hildenbrand , linux-s390 , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Douglas Freimuth References: <20260804162435.28617-1-borntraeger@linux.ibm.com> <20260804162435.28617-4-borntraeger@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20260804162435.28617-4-borntraeger@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=E6P9Y6dl c=1 sm=1 tr=0 ts=6a721ef0 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=WBrIipxYDB_IIsAJn0oA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: 7ziYLvUDsiG2edn1zgR7DPO6xqAoDyfF X-Proofpoint-GUID: 7ziYLvUDsiG2edn1zgR7DPO6xqAoDyfF X-Proofpoint-Spam-Info: AW1haW4tMjYwODA0MDE0MCBTYWx0ZWRfX4XOGfPw6uD21 HIvpoK95CMMECQaXtj3rCjMcN/qN/VG9Vy83Guy2Z1gUCBK2hKKvmnb2cdILL2q4Zefmo8qdSSE c7SzFiCkmRv+1pYvTiiyj1aNeVbabMc= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA0MDE0MCBTYWx0ZWRfX2oxGClG83xkG LAJyegdOKRLv0w73D+B/+bX/EVHoosshZpSe6ft7Tj9as2ga3OK/bm2fjwHA4kzLPxmqGX194yP tMXHIcTtfVcf9J7FRwXtp1jW2IcBUNRLlseV9Nh6LWdu6dtwIiT8YEQEVDyjDjXfC5wE6g7aJAZ OYj4OR7WHhJiRDui8hM1wXHNd1e1WNz6hXmzn0VIjpZxgzHs8nCn01DNlY4/cdzR7Gk44vzwB6r tvXSEHoe0k+t3PUubV6gN948a1n6hK1TnQ0ppoZR/jIliSWAVfVOi5imVDg0TzyvZrlOx4TdMqB D6sgT75dwPw9lAKclZcqOigBzvUV8DDJZ8uUXAaR4BwqCCFB889kmmWQqxl5f3nRFfPD0GyxHDQ naBlE4t73g6RDpdBgat3dkU+flpTxCKdu2vbAskshr09G7TCNNG6qO8f3Dkb48QdBSW7owtefSf VAzTnyekaElEccRpSPg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-04_03,2026-08-04_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 priorityscore=1501 suspectscore=0 adultscore=0 spamscore=0 malwarescore=0 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608040140 On 8/4/26 12:24 PM, Christian Borntraeger wrote: > kvm_s390_reinject_machine_check() fills cr14, mcic, ext_damage_code and > failing_storage_address of the on-stack struct kvm_s390_irq, but struct > kvm_s390_mchk_info also has a pad word and a 16 byte fixed_logout array. > struct mcck_volatile_info carries no logout data, so there is nothing to > copy there and both stay whatever was on the stack. > > __inject_mchk() then memcpy()s fixed_logout into the vcpu local > interrupt state unconditionally. This will reach the guest during > deliver and userspace during migration. > > Reflecting zeroes is the correct behaviour here, as KVM has no logout > data for a reinjected machine check. > > This needs a host machine check while the cpu is in SIE so not trivial > to trigger. > > Fixes: 4d62fcc0b692 ("KVM: s390: Inject machine check into the guest") > Cc: stable@vger.kernel.org > Signed-off-by: Christian Borntraeger Reviewed-by: Matthew Rosato