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Tue, 29 Sep 2026 10:33:59 -0700 From: Shameer Kolothum To: , , CC: , , , , , , , , , , Subject: [RFC PATCH v2 10/16] vfio/pci: Quiesce INTx while access is blocked Date: Tue, 29 Sep 2026 18:32:59 +0100 Message-ID: <20260929173305.204856-11-skolothumtho@nvidia.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260929173305.204856-1-skolothumtho@nvidia.com> References: <20260929173305.204856-1-skolothumtho@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: rnnvmail203.nvidia.com (10.129.68.9) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN3PEPF00022BC7:EE_|CH3PR12MB9121:EE_ X-MS-Office365-Filtering-Correlation-Id: 72ec2384-905e-484a-bf2f-08df1e4feccb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|1800799024|376014|82310400026|36860700016|22082099003|18002099003|6133799003|10067099003|11063799006|56012099006; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 0IJIiXZzFYNVXFKE9mQEVEUpMWbUn+mXn/U3MrxfEIKA2jnfDjCtqCnkVvn0C4An6MslEnOqPA0bZOWjdDxQoVyUTMC98U/6JO4cgKa54sKL7/yO0FURsqPW4QSyaewl0omSFa/s4UgeUDNw05qmRyqEHDDU03tuSS/3KoaMg8HxSuoWEo71XPN6/yUesLWlJGT7nSa+j6vanPwFm2J4H1sKoSYH92CKrJY+mqTpxcEb+i1t9FIeTAqs3v/cXXKGnUP/Hz2DQke5fnQihu59fqzLorMnG/JfKxqA2h+clV7t5Dynrm6iwrJxQ6vlMl8igFjiCThgaDIhhhd8jPmp6DWdmB2OG7n3BaUz0PdpOVhJ91Fk2hNOVzd+2KkNlCgeIZlYg1kTIXI/88Har6MNt3uTHgqfw/VK1ZuqL6m1mlIihvtTWmAwQVJfsnAafe3c X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Sep 2026 17:34:33.2002 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 72ec2384-905e-484a-bf2f-08df1e4feccb X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN3PEPF00022BC7.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9121 The INTx handler and unmask virqfd can access PCI_COMMAND without taking access_srcu. Check the recovery state in these paths under irqlock. Mask pending INTx while access is blocked to prevent an interrupt storm. For shared lines, claim only interrupts identified by pci_check_and_mask_intx(). Record unmask requests for replay when recovery completes. Assisted-by: LLM Signed-off-by: Shameer Kolothum --- drivers/vfio/pci/vfio_pci_intrs.c | 45 +++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 64f80f64ff57..ff29377c1ae8 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -29,6 +29,7 @@ struct vfio_pci_irq_ctx { struct virqfd *mask; char *name; bool masked; + bool unmask_pending; struct irq_bypass_producer producer; }; @@ -49,6 +50,15 @@ static bool is_irq_none(struct vfio_pci_core_device *vdev) vdev->irq_type == VFIO_PCI_MSIX_IRQ_INDEX); } +static bool vfio_pci_recovery_blocks_irq(struct vfio_pci_core_device *vdev) +{ + if (!vdev->pci_recovery_supported) + return false; + + return READ_ONCE(vdev->pci_recovery_enabled) && + READ_ONCE(vdev->access_blocked); +} + static struct vfio_pci_irq_ctx *vfio_irq_ctx_get(struct vfio_pci_core_device *vdev, unsigned long index) @@ -171,6 +181,12 @@ static int vfio_pci_intx_unmask_handler(void *opaque, void *data) int ret = 0; spin_lock_irqsave(&vdev->irqlock, flags); + /* Defer unmasking until recovery completes. */ + if (unlikely(vfio_pci_recovery_blocks_irq(vdev))) { + if (is_intx(vdev)) + ctx->unmask_pending = true; + goto out_unlock; + } /* * Unmasking comes from ioctl or config, so again, have the @@ -182,6 +198,8 @@ static int vfio_pci_intx_unmask_handler(void *opaque, void *data) goto out_unlock; } + ctx->unmask_pending = false; + if (ctx->masked && !vdev->virq_disabled) { /* * A pending interrupt here would immediately trigger, @@ -220,6 +238,24 @@ void vfio_pci_intx_unmask(struct vfio_pci_core_device *vdev) mutex_unlock(&vdev->igate); } +/* Mask INTx for a blocked device. Returns true if this call masked it. */ +static bool vfio_pci_intx_mask_for_recovery(struct vfio_pci_core_device *vdev, + struct vfio_pci_irq_ctx *ctx) +{ + lockdep_assert_held(&vdev->irqlock); + + if (ctx->masked) + return false; + + if (!vdev->pci_2_3) + disable_irq_nosync(vdev->pdev->irq); + else if (!pci_check_and_mask_intx(vdev->pdev)) + return false; + + ctx->masked = true; + return true; +} + static irqreturn_t vfio_intx_handler(int irq, void *dev_id) { struct vfio_pci_irq_ctx *ctx = dev_id; @@ -228,6 +264,14 @@ static irqreturn_t vfio_intx_handler(int irq, void *dev_id) int ret = IRQ_NONE; spin_lock_irqsave(&vdev->irqlock, flags); + if (unlikely(vfio_pci_recovery_blocks_irq(vdev))) { + /* Mask pending INTx to prevent an interrupt storm. */ + if (vfio_pci_intx_mask_for_recovery(vdev, ctx)) + ret = IRQ_HANDLED; + else if (ctx->masked && !vdev->pci_2_3) + ret = IRQ_HANDLED; + goto out_unlock; + } if (!vdev->pci_2_3) { disable_irq_nosync(vdev->pdev->irq); @@ -239,6 +283,7 @@ static irqreturn_t vfio_intx_handler(int irq, void *dev_id) ret = IRQ_HANDLED; } +out_unlock: spin_unlock_irqrestore(&vdev->irqlock, flags); if (ret == IRQ_HANDLED) -- 2.43.0