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Mon, 28 Sep 2026 11:04:36 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (smtpav07.fra02v.mail.ibm.com [10.20.54.106]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 68SB4We643843880 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 28 Sep 2026 11:04:32 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8409420043; Mon, 28 Sep 2026 11:04:32 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E8F6D20040; Mon, 28 Sep 2026 11:04:28 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.124.213.68]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 28 Sep 2026 11:04:28 +0000 (GMT) From: Shrikanth Hegde To: maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, chzigotzky@xenosoft.de Cc: sshegde@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, christophe.leroy@csgroup.eu, linux-kernel@vger.kernel.org, msuchanek@suse.de, ritesh.list@gmail.com, harshpb@linux.ibm.com, gautam@linux.ibm.com, amachhiw@linux.ibm.com, venkat88@linux.ibm.com, nnmlinux@linux.ibm.com Subject: [PATCH 2/2] KVM: PPC: Replay pending interrupts before entering the guest Date: Mon, 28 Sep 2026 16:34:11 +0530 Message-ID: <20260928110411.844582-3-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260928110411.844582-1-sshegde@linux.ibm.com> References: <20260928110411.844582-1-sshegde@linux.ibm.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=FYWiV5+6 c=1 sm=1 tr=0 ts=6aba49c5 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=j_Z4ZgiU5xnDcWkxdewA:9 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI4MDA0MiBTYWx0ZWRfXxBmq/wGMBqch y3KVGbHhIpZ7EjSO4NDCZy43gfm/NuA1USKZcBp9yt+mOw0xndOK3su7MZikZ2XRYq/sve1bVkN wt0Tic4ILbHsUqCFNF68I694eDoVmVo= X-Proofpoint-ORIG-GUID: ydNCXtBfZL86Wr8r1PqOtlvBFyu7KEAl X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI4MDA0MiBTYWx0ZWRfX7cqjpIKOZ2Pf 6RtzM5X7L9wODi4k1BNp8aZrBVkLY3oqaoA2QAiWIKwD3jr+6fTM6Oe/BaEvSYtBpxV31LWvGgo 7K3fv0CsftJSa4FjUQyRx4vxnLKPhQdNC4PjcZENk6gkTCp1nLyCa9kX+e361218xQ8OLPASX4m QUsAt2jOL49Yz0v2yH9ixsLTk+GeiUfSmxl9lDqFOgA2wDP1V2bYFMNERxh75MGezEMv6/N1LJf 9jigI/TyLlX0Kai6fIIxRNCCHN0jMA6MEVfI4dK3Z5s5iO7WKI3QZZ4+w6FOjhfZcwKHFNAGfqp JosWgBGYQ7Ta0bdmT4G8qctgXGHnvygOUfgi1ryMHrfaEzfs7Ig2qQ0HgK9ffpVIjgEyzHP1Ag4 bJ/7rWT4uvol/KgGOwoZexwPGiI07RELgqfbG5INj5bGff1xJqs+b63DOJITXv8/XS8m7uRTgAp FZ0hJZ0YrmkMBhvu7jg== X-Proofpoint-GUID: M2HdvUP8cMJ2QYlC_JztXMpa7DVqP79E 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=2026-09-28_02,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 impostorscore=0 spamscore=0 phishscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609280042 After applying preempt disable patch, i.e PATCH 1/2, Christian reported a subsequent warning stopping his board to boot properly. WARNING: at .kvmppc_fix_ee_before_entry+0x10/0x28, CPU#0: qemu-system-ppc/4667 CPU: 0 UID: 1000 PID: 4667 Comm: qemu-system-ppc Tainted: G W 7.3.0-rc4-2-powerpc64-smp #1 PREEMPT Tainted: [W]=WARN Hardware name: varisys,CYRUS5040 e5500 0x80240012 CoreNet Generic NIP [c00000000005dc3c] .kvmppc_fix_ee_before_entry+0x10/0x28 LR [c00000000005f298] .kvmppc_handle_exit+0x5b4/0x5e8 Call Trace: [c000000086587780] [c00000000005ee10] .kvmppc_handle_exit+0x12c/0x5e8 (unreliable) [c000000086587830] [c000000000062068] .kvmppc_resume_host+0xb8/0x10c It triggers below warning... static inline void kvmppc_fix_ee_before_entry(void) { trace_hardirqs_on(); /* * To avoid races, the caller must have gone directly from having * interrupts fully-enabled to hard-disabled. */ WARN_ON(local_paca->irq_happened != PACA_IRQ_HARD_DIS); This happens since kvmppc_prepare_to_enter does first local_irq_disable followed by hard_irq_disable. This leaves a small window where interrupt may occur and it could set the irq pending bit in PACA. When that happens replay that interrupt before entering the guest. Fixes: 12013e3d4695 ("KVM: powerpc: Use generic xfer to guest work function") Reported-by: Christian Zigotzky Closes: https://lore.kernel.org/all/b8f82519-9ae5-c247-e020-e79c627e57df@xenosoft.de/ Signed-off-by: Shrikanth Hegde --- arch/powerpc/kvm/powerpc.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c index 9194cf492d1c..847ff07c364b 100644 --- a/arch/powerpc/kvm/powerpc.c +++ b/arch/powerpc/kvm/powerpc.c @@ -147,6 +147,19 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) continue; } +#ifdef CONFIG_PPC64 + /* + * Interrupt arrived between the soft and hard + * disable. Replay it and retry guest entry. + */ + if (unlikely(local_paca->irq_happened != PACA_IRQ_HARD_DIS)) { + local_irq_enable(); + local_irq_disable(); + hard_irq_disable(); + continue; + } +#endif + guest_enter_irqoff(); return 1; } -- 2.52.0