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Fri, 13 Nov 2026 07:48:56 +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 07:48:56 +0000 (GMT) Message-ID: <24f5303f-19d9-41c4-826d-b2a777008e87@linux.ibm.com> Date: Fri, 13 Nov 2026 13:18:55 +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 3/3] KVM: PPC: Use ppc_hard_irq_disable before guest entry 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> <20261112130913.4124175-4-sshegde@linux.ibm.com> Content-Language: en-US From: Narayana Murty N In-Reply-To: <20261112130913.4124175-4-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: AW1haW4tMjYxMTEzMDAzMCBTYWx0ZWRfX878ZmJvolgTZ Wt/zK4a4coekuNhgGDwBt98tGyYCnApZHn1e+iSVKCdZr2NqucL1X0WNQwE3YRd7ILv+hJh43OM FBnOFLqZCwzM+zaw+rEK5HAz7rs/qPs= X-Authority-Analysis: v=2.4 cv=HbCB3SE8 c=1 sm=1 tr=0 ts=6af6c0f1 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=jkjrswUoTJZ6kdcGLO8A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: mkgzvKllCj9yNTLhZCzhE44HrOLi1nYS X-Proofpoint-GUID: 9y4abnksacH48eUbDO8BLwBJ5BUJdio_ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTEzMDAzMCBTYWx0ZWRfXy9B8pG/BP3GH pGEb4DU1rNasanq3oGI+MESGqZ1exOJo+hchupNyiMXAJdTb+nGii0W38aCx5AETl+4TEP6DSR6 ZmHVFzKPYr1Qun3Ddq55rPKW18aTq8CdatZEaMrcoksfsR7zVvjGXAZqMpdm4vnDDUvF5Zk/2XW RG2GL44aoltImdmNPNkEswkmICKpGzCE5kAoXbu6uznVda96vSvKr/+LUreyYky2Ns8EC+z0YQy R4i/e+w1PpZv1bv4jrw5qD/DWR19Xyb7tI4f1f2RMwMNAGiz42EGGeCAaQ+5gk44HNBxCuqUFBm hGHUJQwZRLZ+KVgcLJdXh4jKvQH6udcf8eecIHLoztz2/tZK8ODAE7J54cbbftSPENPhKvx9b24 eaTbwep6J6s/i9E8y4tyop5zNh2EY0nc3puZAbiZbmrjAhFEAdDMTCoauxC9WZFEGo09t26ulWD 5Bb3qyTDQVvsrgpQidg== 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 malwarescore=0 adultscore=0 spamscore=0 bulkscore=0 phishscore=0 impostorscore=0 priorityscore=1501 clxscore=1015 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611130030 Hi, On 12/11/26 6:39 PM, Shrikanth Hegde wrote: > After applying preempt disable patch, i.e PATCH 2/3, 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. > > That local_irq_disable was necessary for PPC32 to track the lockdep > state etc. On PPC64 hard_irq_disable is good enough. There is no need to > do both. Use the new irq api to do the necessary one. > > 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/ > Tested-by: Christian Zigotzky > Reviewed-by: Mukesh Kumar Chaurasiya (IBM) > Signed-off-by: Shrikanth Hegde > --- > arch/powerpc/kvm/booke.c | 3 +-- > arch/powerpc/kvm/powerpc.c | 14 +++----------- > 2 files changed, 4 insertions(+), 13 deletions(-) > > diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > index aed7b476b7eb..1ba28848e8bc 100644 > --- a/arch/powerpc/kvm/booke.c > +++ b/arch/powerpc/kvm/booke.c > @@ -722,8 +722,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu) > if (vcpu->arch.shared->msr & MSR_WE) { > local_irq_enable(); > kvm_vcpu_halt(vcpu); > - local_irq_disable(); > - hard_irq_disable(); > + ppc_hard_irq_disable(); > > kvmppc_set_exit_type(vcpu, EMULATED_MTMSRWE_EXITS); > r = 1; > diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c > index 9194cf492d1c..4ee3d7bfe917 100644 > --- a/arch/powerpc/kvm/powerpc.c > +++ b/arch/powerpc/kvm/powerpc.c > @@ -81,13 +81,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) > int r; > > WARN_ON(irqs_disabled()); > - /* > - * local_irq_disable() first: on 32-bit, hard_irq_disable() alone is a > - * raw MSR[EE] clear that bypasses the lockdep/irq-tracing state, and > - * the xfer_to_guest_mode helpers assert IRQs are seen as disabled. > - */ > - local_irq_disable(); > - hard_irq_disable(); > + ppc_hard_irq_disable(); > > while (true) { > xfer_to_guest_mode_prepare(); > @@ -101,8 +95,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) > */ > local_irq_enable(); > r = kvm_xfer_to_guest_mode_handle_work(vcpu); > - local_irq_disable(); > - hard_irq_disable(); > + ppc_hard_irq_disable(); > if (r) { > /* > * The generic helper does not set the exit > @@ -134,8 +127,7 @@ int kvmppc_prepare_to_enter(struct kvm_vcpu *vcpu) > local_irq_enable(); > trace_kvm_check_requests(vcpu); > r = kvmppc_core_check_requests(vcpu); > - local_irq_disable(); > - hard_irq_disable(); > + ppc_hard_irq_disable(); > if (r > 0) > continue; > break; The changes look good to me. Using ppc_hard_irq_disable() directly on PPC64 avoids the soft-disable to hard-disable window, while preserving the software IRQ mask and tracing state required by the guest-entry path. The BookE halt path and the guest-work retry paths are covered as well. Reviewed-by: Narayana Murty N nnmlinux@linux.ibm.com