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Thu, 12 Nov 2026 13:09:32 +0000 (GMT) Received: from li-7bb28a4c-2dab-11b2-a85c-887b5c60d769.ibm.com.com (unknown [9.39.18.47]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 12 Nov 2026 13:09:32 +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, mkchauras@gmail.com Subject: [PATCH v3 3/3] KVM: PPC: Use ppc_hard_irq_disable before guest entry Date: Thu, 12 Nov 2026 18:39:13 +0530 Message-ID: <20261112130913.4124175-4-sshegde@linux.ibm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261112130913.4124175-1-sshegde@linux.ibm.com> References: <20261112130913.4124175-1-sshegde@linux.ibm.com> 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 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=J+M/fwnS c=1 sm=1 tr=0 ts=6af5ba95 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=zJRp6_cAMcgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=VnNF1IyMAAAA:8 a=SkEQ8EbvhdlHpgZ8pF0A:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMTEyMDA1MCBTYWx0ZWRfX0X2U15DzsuEK 4mF2K3PJ7pHcBNyDV/rNA8A1Lr9h1dvFIpFpIiZZpYwFvPTjvJrxfUFOcNUp0E8uDytq3Z40E1n RdlQeC6CQnvT3Q4S5b8Q8YHUh+6wAY6t9CZ+kcPiqKFKltEmEpMxJQLbG/n0Pz/iMIwgIyg4gmk wPGIFF/8MWdKT1INnTXy25IFHYdLRchKT53CsibyXkwSyGk4ZnMDg8iL965SkS13KlabQrt1AXU bwDABGLpVexL7OQ5QgL4His/QLZM3pae2NKoNPsxZrfsEPHPc6n0jjKjYGL12zLEnTnsunG78jF 0aZJLP2Itixq3PFJoNLSkvVI/b8VqKXgtizv0phzb/cfsk/WDliPc+oGtxtYQwIhs76fmpeyJNX UfC86/z0//nMWnH+YToprylfExcog6xhaAVhwEQjCCf9fXI+iSLEYdbn7fowll7RFPOqyHGZPhP KiLLeHlJkrkVI2dBTVA== X-Proofpoint-Spam-Info: AW1haW4tMjYxMTEyMDA1MCBTYWx0ZWRfX/iCtcI092T8L 788tuSxG1ZtLJFK5tsS3Y5WCIO97KLE63IMjl7el0EI+F7DBL5CHbs/vtaVZvkqNwOdBvbGIuXP GvI56NfvgxxvsoJvYnLiyo31abnkCQY= X-Proofpoint-GUID: Kch17STND8cqv_2vGzVKNnzGBdQrVuiQ X-Proofpoint-ORIG-GUID: ww6IZzwLdaZVVKxu8wClHTVAB6xC8BdZ 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=2026-11-12_01,2026-11-11_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 bulkscore=0 adultscore=0 suspectscore=0 malwarescore=0 clxscore=1015 priorityscore=1501 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2611040001 definitions=main-2611120050 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; -- 2.52.0