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Thu, 9 Jul 2026 09:39:10 +0000 (GMT) Date: Thu, 9 Jul 2026 15:09:33 +0530 From: Amit Machhiwal To: leixiang Cc: seanjc@google.com, pbonzini@redhat.com, stable@vger.kernel.org, Madhavan Srinivasan , Nicholas Piggin , Michael Ellerman , "Christophe Leroy (CS GROUP)" , Suresh Warrier , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: PPC: Book3S HV: Set irqfd->producer only on success Message-ID: <20260709150215.e5b5af63-43-amachhiw@linux.ibm.com> Mail-Followup-To: leixiang , seanjc@google.com, pbonzini@redhat.com, stable@vger.kernel.org, Madhavan Srinivasan , Nicholas Piggin , Michael Ellerman , "Christophe Leroy (CS GROUP)" , Suresh Warrier , Paul Mackerras , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260709055755.31297-1-leixiang@kylinos.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260709055755.31297-1-leixiang@kylinos.cn> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA5MDA4OSBTYWx0ZWRfX0J8Kx25YbE25 gEKF/7pooXdZT5w2Ana836uEphAVHc51zuQyuiCckgLkullwvVqhD27s5+O3jxr7yjsLJ1qEWto M/TFd5KcrnU6ZCNi6yjlkXo/uY2KLdo= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA5MDA4OSBTYWx0ZWRfX/tF6QwN3C+Hu ELnzvTFlZW8BmZAF6YGV1s97Nt8NYWU12kEb39Q9ZeR6FCKPMw2XJINZ14fht5Xkv1+9oiLe7zN RXNuCfQ+1XidblYy5gwGTZVwGIydiMcPu/HW3uWcHiMdP0svvYUk9WmtCy82fRCJAliLMuNCS98 nxkk5ZNwf1/OpwollX5I3+eFdtYGKyUDzZtukCUpTZ7xxYU8G82Fpwq6j6aZIjkYpAbVxaA5zKT u6L/CZ/1aourPoRhz8Qd5Jt4WOYJRhBdLIR/fGzFKuzv/n4fXMDedCznPte2bzqcX5YlYAQjBru NOpqgLVbKMact4TdZaBOrq4ZyAOeLd2rjWz8qEI8MAh0iR+GUqjP0WDVzYYQIaCxagYHh75ZEu/ UXDi37wkNFQBEv6yKJIkm/ODzINhu63c7ICiZuBB9kuZ0pg6IxgMyYKqtIvoOM5myqRCf2iu7OC NIklSjUVC1BR1Z1HvQA== X-Proofpoint-GUID: ZJlaxRQCVLZf1W0xgI-7SUYf5knbDxjI X-Authority-Analysis: v=2.4 cv=Oot/DS/t c=1 sm=1 tr=0 ts=6a4f6c44 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=1XWaLZrsAAAA:8 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=aQTDHXOw4a3q5qQiMUEA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: 3PrTwKRV1brcDspQTSDzvnlPTg6EvwHR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-09_01,2026-07-08_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 lowpriorityscore=0 clxscore=1011 impostorscore=0 phishscore=0 malwarescore=0 suspectscore=0 spamscore=0 adultscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607090089 On 2026/07/09 01:57 PM, leixiang wrote: > Set irqfd->producer only after kvmppc_set_passthru_irq() succeeds to > avoid leaving a dangling pointer on failure. The bypass manager does > not register a failed producer, so the pointer is never cleared. > > Fixes: c57875f5f9be ("KVM: PPC: Book3S HV: Enable IRQ bypass") > Suggested-by: Sean Christopherson > Cc: stable@vger.kernel.org > Signed-off-by: leixiang > --- > arch/powerpc/kvm/book3s_hv.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 61dbeea317f3..ff7b25629125 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -6111,12 +6111,12 @@ static int kvmppc_irq_bypass_add_producer_hv(struct irq_bypass_consumer *cons, > struct kvm_kernel_irqfd *irqfd = > container_of(cons, struct kvm_kernel_irqfd, consumer); > > - irqfd->producer = prod; > - > ret = kvmppc_set_passthru_irq(irqfd->kvm, prod->irq, irqfd->gsi); > if (ret) > pr_info("kvmppc_set_passthru_irq (irq %d, gsi %d) fails: %d\n", > prod->irq, irqfd->gsi, ret); > + else > + irqfd->producer = prod; cons->add_producer is invoked by __connect() in virt/lib/irqbypass.c, which itself is called from either irq_bypass_register_consumer() or irq_bypass_register_producer(). __connect() only records the pairing — setting cons->producer and prod->consumer — if add_producer returns 0. static int __connect(struct irq_bypass_producer *prod, struct irq_bypass_consumer *cons) { [...] if (!ret) { prod->consumer = cons; cons->producer = prod; } On failure, no pairing is recorded, so __disconnect() is never called, and del_producer is never invoked to clear irqfd->producer. The old unconditional assignment indeed left a dangling pointer on any kvmppc_set_passthru_irq() failure. Reviewed-by: Amit Machhiwal ~Amit > > return ret; > } > -- > 2.45.0