linux-kernel - [PATCH v11 10/13] vfio/pci: Register and allow DMA FAULT IRQ signaling

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Date:   Mon, 16 Nov 2020 12:00:27 +0100
From:   Eric Auger <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, eric.auger@...hat.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, will@...nel.org,
        joro@...tes.org, maz@...nel.org, robin.murphy@....com,
        alex.williamson@...hat.com
Cc:     jean-philippe@...aro.org, zhangfei.gao@...aro.org,
        zhangfei.gao@...il.com, vivek.gautam@....com,
        shameerali.kolothum.thodi@...wei.com,
        jacob.jun.pan@...ux.intel.com, yi.l.liu@...el.com, tn@...ihalf.com,
        nicoleotsuka@...il.com, yuzenghui@...wei.com
Subject: [PATCH v11 10/13] vfio/pci: Register and allow DMA FAULT IRQ signaling

Register the VFIO_IRQ_TYPE_NESTED/VFIO_IRQ_SUBTYPE_DMA_FAULT
IRQ that allows to signal a nested mode DMA fault.

Signed-off-by: Eric Auger <eric.auger@...hat.com>

---

v10 -> v11:
- the irq now is registered in vfio_pci_dma_fault_init()
  in case the domain is nested
---
 drivers/vfio/pci/vfio_pci.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 93e03a4a5f32..65a83fd0e8c0 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -397,6 +397,7 @@ int vfio_pci_iommu_dev_fault_handler(struct iommu_fault *fault, void *data)
 		(struct vfio_region_dma_fault *)vdev->fault_pages;
 	struct iommu_fault *new;
 	u32 head, tail, size;
+	int ext_irq_index;
 	int ret = -EINVAL;
 
 
@@ -422,7 +423,19 @@ int vfio_pci_iommu_dev_fault_handler(struct iommu_fault *fault, void *data)
 	ret = 0;
 unlock:
 	mutex_unlock(&vdev->fault_queue_lock);
-	return ret;
+	if (ret)
+		return ret;
+
+	ext_irq_index = vfio_pci_get_ext_irq_index(vdev, VFIO_IRQ_TYPE_NESTED,
+						   VFIO_IRQ_SUBTYPE_DMA_FAULT);
+	if (ext_irq_index < 0)
+		return -EINVAL;
+
+	mutex_lock(&vdev->igate);
+	if (vdev->ext_irqs[ext_irq_index].trigger)
+		eventfd_signal(vdev->ext_irqs[ext_irq_index].trigger, 1);
+	mutex_unlock(&vdev->igate);
+	return 0;
 }
 
 #define DMA_FAULT_RING_LENGTH 512
@@ -474,6 +487,12 @@ static int vfio_pci_dma_fault_init(struct vfio_pci_device *vdev)
 	if (ret) /* the dma fault region is freed in vfio_pci_disable() */
 		goto out;
 
+	ret = vfio_pci_register_irq(vdev, VFIO_IRQ_TYPE_NESTED,
+				    VFIO_IRQ_SUBTYPE_DMA_FAULT,
+				    VFIO_IRQ_INFO_EVENTFD);
+	if (ret) /* the fault handler is also freed in vfio_pci_disable() */
+		goto out;
+
 	return 0;
 out:
 	kfree(vdev->fault_pages);
-- 
2.21.3