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Fri, 13 Nov 2026 07:45:58 +0000 (GMT) Received: from [9.39.16.227] (unknown [9.39.16.227]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 13 Nov 2026 07:45:58 +0000 (GMT) Message-ID: <8a88f1bc-2ff5-4d6d-8f7c-1182b256d855@linux.ibm.com> Date: Fri, 13 Nov 2026 13:15:57 +0530 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] KVM: PPC: BookE: Load FP and Altivec before enabling the interrupts To: Shrikanth Hegde , maddy@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, chzigotzky@xenosoft.de Cc: 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, mkchauras@gmail.com References: <20261112130913.4124175-1-sshegde@linux.ibm.com> <20261112130913.4124175-3-sshegde@linux.ibm.com> Content-Language: en-US From: Narayana Murty N In-Reply-To: <20261112130913.4124175-3-sshegde@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYxMTEzMDAzMCBTYWx0ZWRfX6fgTPRPDx9AN Jmipqjb8YSZHtegR7QmsfOx+znWRAPn0IzZCQzcx1Yb3mraWpRpHKf+DqA7jWsPBCHP6N0nbCgq MRjudsQnzbBCUYl9EsC/ClvQ+Qc06NA= X-Authority-Analysis: v=2.4 cv=GISdgeNK c=1 sm=1 tr=0 ts=6af6c03f cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=7zvpPTbqLWkq6IA-fN0A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: O8kOlERyROXO3xBswdO-Z0TxPGYUQD1- X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTEzMDAzMCBTYWx0ZWRfXxyxZfZezlFxr IVZI5Z/UPOltHvj+C8fiUvlpRFmgh9bCGgAzbjEbLK9kulv2PCllZfR+V2Uw/h0WwBI1CdmlSqH XmLQuVHcmlF9T5fMHD8qYpy8FALCWuGZAnMvM2iTKuLs47tnFh1ZUt4vp3k5JYN20EAF6IH5enc UR8MPgql/cj2eXqFSGm2rz3xNYGGsPtlfcXGYMdDjxEdz/DOGueUo17gwjuDCUggsEEs19QXMmk gbNeEK03QWOz6+JcHteiSLL38s9GNd6Rc/Nuvk1U2m92pDjss7T0rNGDviayoxUocFOW9mDKoBb m3vIFgbqJ2uk/dyaTDDG4AK0nWSNMPMIAoNNi4KRegmVJyiDmq007lBNYlDFi7IhMyt53Q4ZUJz wbbOTfIf3Dkibp4PVEfjpBat4uCI0fgCa5s5hSk31+5jF9wlZZYR+4J/KdWrwJcvEEUmCLQZKL4 meFFxjeJjl2U/Wzla0g== X-Proofpoint-ORIG-GUID: 1nyDaK8FP75mDiLpG1vaYqvVshQ8bL45 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-11-13_02,2026-11-11_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 impostorscore=0 clxscore=1015 adultscore=0 priorityscore=1501 phishscore=0 spamscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611130030 Hi Shrikanth, On 12/11/26 6:39 PM, Shrikanth Hegde wrote: > Christian reported that booting preemptible kernel on FSL Cyrus+ board > causes boot hang. > > The logs pointed that system was busy in printing below warning. > > WARNING: at .enable_kernel_fp+0x30/0x78, CPU#3: qemu-system-ppc/4884 > Modules linked in: > CPU: 3 UID: 1000 PID: 4884 Comm: qemu-system-ppc Not tainted 7.3.0-rc1-powerpc64-smp-preempt #1 PREEMPT > NIP [c000000000003338] .enable_kernel_fp+0x30/0x78 > LR [c00000000005de84] .kvmppc_load_guest_fp+0x30/0x80 > Call Trace: > [c000000085ca7700] [c00000000005de84] .kvmppc_load_guest_fp+0x30/0x80 > [c000000085ca7780] [c00000000005f2a0] .kvmppc_handle_exit+0x5bc/0x5cc > [c000000085ca7830] [c00000000006204c] .kvmppc_resume_host+0xb8/0x10c > > Which is... > > void enable_kernel_fp(void) > { > unsigned long cpumsr; > WARN_ON(preemptible()); > > And... > > Though irq's are hard disabled after kvmppc_prepare_to_enter, but > kvmppc_fix_ee_before_entry enables the softmask's IRQ state. > That causes the irqs_disabled to return false. > Hence leading to the warnings. > > Fix it by re-ordering the code to load the FP and Altivec > before enabling the softmask IRQ state. > > Suggested-by: Narayana Murty N > Fixes: 3efc7da61f6c ("KVM: PPC: Book3E: Increase FPU laziness") > Reported-by: Christian Zigotzky > Closes: https://lore.kernel.org/all/33342fbf-eb7b-bde6-2c8c-254fe8bfb993@xenosoft.de/ > Tested-by: Christian Zigotzky > Reviewed-by: Mukesh Kumar Chaurasiya (IBM) > Signed-off-by: Shrikanth Hegde > --- > arch/powerpc/kvm/booke.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > index 13ad4cf5fa71..aed7b476b7eb 100644 > --- a/arch/powerpc/kvm/booke.c > +++ b/arch/powerpc/kvm/booke.c > @@ -1404,10 +1404,9 @@ int kvmppc_handle_exit(struct kvm_vcpu *vcpu, unsigned int exit_nr) > if (s <= 0) > r = (s << 2) | RESUME_HOST | (r & RESUME_FLAG_NV); > else { > - /* interrupts now hard-disabled */ > - kvmppc_fix_ee_before_entry(); > kvmppc_load_guest_fp(vcpu); > kvmppc_load_guest_altivec(vcpu); > + kvmppc_fix_ee_before_entry(); > } > } > This address my previous comment, feel free to add Reviewed-by Narayana Murty N thanks, Narayana.