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[86.49.245.11]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6aaecf2f62esm4040194a12.27.2026.09.28.07.31.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 07:31:39 -0700 (PDT) From: Andrew Jones To: iommu@lists.linux.dev, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Cc: tomasz.jeznach@linux.dev, jgg@ziepe.ca, jgg@nvidia.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, pjw@kernel.org, palmer@dabbelt.com, tglx@kernel.org, anup@brainfault.org, atish.patra@linux.dev, fangyu.yu@linux.alibaba.com, zhangzhanpeng.jasper@bytedance.com, zong.li@sifive.com Subject: [RFC PATCH v3 04/14] iommu/riscv: Reject live S2 replacement with forwarded IRQs Date: Mon, 28 Sep 2026 16:31:03 +0200 Message-ID: <20260928143113.49838-5-andrew.jones@oss.qualcomm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260928143113.49838-1-andrew.jones@oss.qualcomm.com> References: <20260928143113.49838-1-andrew.jones@oss.qualcomm.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTI4MDA1OCBTYWx0ZWRfXypgbYFLY0UFm BqnaSH2R0EjQNEik9F/aHdMFvE9fS/ruZvhvvBTTqwjDzLNaB0Zj7ZjMglc4aQLtN3CCgqhc05K dliuCpINf0ebaQnW4xUDxq7s0IVEhhe3aMsTC7mqsbI/cuUyxVqzVeZ+hw8X8lj4e0rVcg2vAeQ Aap1bFB5mc5auj/vXxM937VRAlhEl7O9fJWPmBqYSGuxOsEyUhejMbThV8azH5RNEUD2zvy3P7t Xk4uU6CKWeXqiw75x+tbbdIr/wWF72I0bKTxCmxt92erE2TGvP4MTzrcSJy3D4Mjcg7t028NrWW t2/jyTo9k9JdYaiw7N1+Z3/opRX7VtDDdUnIXbQ0uPSH7ILn0+nN9t3zJ0gcUdFzFzVlAyHYsxt kM+8glcPUFr4cisZ2JAcbLIMqUUT+m8JXo7E8J6c5V1FjU9caAxC5OkPMOiJKhsuKBrw4hVth1D ZJglmXTmjbC1gsTkF9g== X-Authority-Analysis: v=2.4 cv=e6aT2qp/ c=1 sm=1 tr=0 ts=6aba7bad cx=c_pps a=ULNsgckmlI/WJG3HAyAuOQ==:117 a=4CXLxsOAgPM/krjtHEZQyA==:17 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=EUspDBNiAAAA:8 a=t97w11WlQ40Dee02AfYA:9 a=1WsBpfsz9X-RYQiigVTh:22 X-Proofpoint-GUID: VhWkpKdDZssckNo_UtgrwQwo59kGp_kO X-Proofpoint-ORIG-GUID: VhWkpKdDZssckNo_UtgrwQwo59kGp_kO X-Proofpoint-Spam-Info: AW1haW4tMjYwOTI4MDA1OCBTYWx0ZWRfXw+tm7teqNKyA 4b+vk/YgUae94oXy7x04/Qg/JNGzhNooM9f358lfCx69yIEJ1VzUiseER+YKa5+FzowJ7wB/MU6 3ZycwtiXM0kJmnI0MSoI/tMK8eA/xEs= 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_03,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 adultscore=0 suspectscore=0 bulkscore=0 clxscore=1015 impostorscore=0 malwarescore=0 phishscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609280058 MSI forwarding state is tied to the S2 domain MSI table. Replacing a device's S2 domain while one of its IRQs is forwarded would leave the IRQ state referring to the detached table. Reject direct S2-to-S2 replacement when the moving device has forwarded IRQs. Introduce a per-device nr_forwarded_irqs counter, rather than domain-wide accounting, so other devices in the same IOMMU group can still move and can be rolled back if a later device fails. Later patches which introduce interrupt remapping support will manage the newly introduced nr_forwarded_irqs counter. Signed-off-by: Andrew Jones --- drivers/iommu/riscv/iommu.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c index 57f2884dec42..d48667112cd9 100644 --- a/drivers/iommu/riscv/iommu.c +++ b/drivers/iommu/riscv/iommu.c @@ -872,6 +872,7 @@ PT_IOMMU_CHECK_DOMAIN(struct riscv_iommu_domain, riscvpt.iommu, domain); /* Private IOMMU data for managed devices, dev_iommu_priv_* */ struct riscv_iommu_info { struct riscv_iommu_domain *domain; + unsigned int nr_forwarded_irqs; }; static struct riscv_iommu_msi_table *riscv_iommu_domain_msi_table(struct iommu_domain *iommu_domain) @@ -1432,6 +1433,36 @@ static int riscv_iommu_msi_table_alloc(struct riscv_iommu_domain *domain, return 0; } +static bool riscv_iommu_can_attach_paging_domain(struct iommu_domain *iommu_domain, + struct device *dev, + struct iommu_domain *old) +{ + struct riscv_iommu_domain *domain = iommu_domain_to_riscv(iommu_domain); + struct riscv_iommu_info *info = dev_iommu_priv_get(dev); + bool new_is_s2 = domain->gscid; + struct riscv_iommu_msi_table *new_msi_table, *old_msi_table; + + if (iommu_domain == old) + return true; + + new_msi_table = riscv_iommu_domain_msi_table(iommu_domain); + old_msi_table = riscv_iommu_domain_msi_table(old); + + if (new_msi_table) + lockdep_assert_held(&new_msi_table->lock); + if (old_msi_table) + lockdep_assert_held(&old_msi_table->lock); + + /* + * Per-device accounting allows other devices in the same IOMMU group + * to move or roll back while this device has forwarded interrupts. + */ + if (new_is_s2 && old_msi_table && info->nr_forwarded_irqs) + return false; + + return true; +} + static int riscv_iommu_attach_paging_domain(struct iommu_domain *iommu_domain, struct device *dev, struct iommu_domain *old) @@ -1477,6 +1508,11 @@ static int riscv_iommu_attach_paging_domain(struct iommu_domain *iommu_domain, bond->dev = dev; flags = riscv_iommu_msi_tables_lock(old, iommu_domain); + if (!riscv_iommu_can_attach_paging_domain(iommu_domain, dev, old)) { + riscv_iommu_msi_tables_unlock(old, iommu_domain, flags); + kfree(bond); + return -EBUSY; + } riscv_iommu_bond_link(domain, bond); riscv_iommu_iodir_update(iommu, dev, &dc); riscv_iommu_bond_unlink(info->domain, dev); -- 2.43.0