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From: Eric Auger <eric.auger@redhat.com>
To: eric.auger.pro@gmail.com, eric.auger@redhat.com,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	joro@8bytes.org, alex.williamson@redhat.com,
	jacob.jun.pan@linux.intel.com, yi.l.liu@intel.com,
	jean-philippe.brucker@arm.com, will.deacon@arm.com,
	robin.murphy@arm.com
Cc: kevin.tian@intel.com, vincent.stehle@arm.com,
	ashok.raj@intel.com, marc.zyngier@arm.com, tina.zhang@intel.com
Subject: [PATCH v9 05/11] vfio/pci: Register an iommu fault handler
Date: Thu, 11 Jul 2019 15:56:19 +0200
Message-ID: <20190711135625.20684-6-eric.auger@redhat.com> (raw)
In-Reply-To: <20190711135625.20684-1-eric.auger@redhat.com>

Register an IOMMU fault handler which records faults in
the DMA FAULT region ring buffer. In a subsequent patch, we
will add the signaling of a specific eventfd to allow the
userspace to be notified whenever a new fault as shown up.

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

---

v8 -> v9:
- handler now takes an iommu_fault handle
- eventfd signaling moved to a subsequent patch
- check the fault type and return an error if != UNRECOV
- still the fault handler registration can fail. We need to
  reach an agreement about how to deal with the situation

v3 -> v4:
- move iommu_unregister_device_fault_handler to vfio_pci_release
---
 drivers/vfio/pci/vfio_pci.c | 42 +++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 3b091cfdaf46..c6fdbd64bfb2 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -27,6 +27,7 @@
 #include <linux/vfio.h>
 #include <linux/vgaarb.h>
 #include <linux/nospec.h>
+#include <linux/circ_buf.h>
 
 #include "vfio_pci_private.h"
 
@@ -281,6 +282,38 @@ static const struct vfio_pci_regops vfio_pci_dma_fault_regops = {
 	.add_capability = vfio_pci_dma_fault_add_capability,
 };
 
+int vfio_pci_iommu_dev_fault_handler(struct iommu_fault *fault, void *data)
+{
+	struct vfio_pci_device *vdev = (struct vfio_pci_device *)data;
+	struct vfio_region_dma_fault *reg =
+		(struct vfio_region_dma_fault *)vdev->fault_pages;
+	struct iommu_fault *new =
+		(struct iommu_fault *)(vdev->fault_pages + reg->offset +
+			reg->head * reg->entry_size);
+	int head, tail, size;
+	int ret = 0;
+
+	if (fault->type != IOMMU_FAULT_DMA_UNRECOV)
+		return -ENOENT;
+
+	mutex_lock(&vdev->fault_queue_lock);
+
+	head = reg->head;
+	tail = reg->tail;
+	size = reg->nb_entries;
+
+	if (CIRC_SPACE(head, tail, size) < 1) {
+		ret = -ENOSPC;
+		goto unlock;
+	}
+
+	*new = *fault;
+	reg->head = (head + 1) % size;
+unlock:
+	mutex_unlock(&vdev->fault_queue_lock);
+	return ret;
+}
+
 #define DMA_FAULT_RING_LENGTH 512
 
 static int vfio_pci_init_dma_fault_region(struct vfio_pci_device *vdev)
@@ -315,6 +348,13 @@ static int vfio_pci_init_dma_fault_region(struct vfio_pci_device *vdev)
 	header->entry_size = sizeof(struct iommu_fault);
 	header->nb_entries = DMA_FAULT_RING_LENGTH;
 	header->offset = sizeof(struct vfio_region_dma_fault);
+
+	ret = iommu_register_device_fault_handler(&vdev->pdev->dev,
+					vfio_pci_iommu_dev_fault_handler,
+					vdev);
+	if (ret)
+		goto out;
+
 	return 0;
 out:
 	kfree(vdev->fault_pages);
@@ -530,6 +570,8 @@ static void vfio_pci_release(void *device_data)
 	if (!(--vdev->refcnt)) {
 		vfio_spapr_pci_eeh_release(vdev->pdev);
 		vfio_pci_disable(vdev);
+		/* TODO: Failure problematics */
+		iommu_unregister_device_fault_handler(&vdev->pdev->dev);
 	}
 
 	mutex_unlock(&vdev->reflck->lock);
-- 
2.20.1

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  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-11 13:56 [PATCH v9 00/11] SMMUv3 Nested Stage Setup (VFIO part) Eric Auger
2019-07-11 13:56 ` [PATCH v9 01/11] vfio: VFIO_IOMMU_SET_PASID_TABLE Eric Auger
2019-07-11 13:56 ` [PATCH v9 02/11] vfio: VFIO_IOMMU_CACHE_INVALIDATE Eric Auger
2019-07-11 13:56 ` [PATCH v9 03/11] vfio: VFIO_IOMMU_SET_MSI_BINDING Eric Auger
2019-07-11 13:56 ` [PATCH v9 04/11] vfio/pci: Add VFIO_REGION_TYPE_NESTED region type Eric Auger
2019-07-11 13:56 ` Eric Auger [this message]
2019-07-11 13:56 ` [PATCH v9 06/11] vfio/pci: Allow to mmap the fault queue Eric Auger
2019-07-11 13:56 ` [PATCH v9 07/11] vfio: Use capability chains to handle device specific irq Eric Auger
2019-07-11 13:56 ` [PATCH v9 08/11] vfio: Add new IRQ for DMA fault reporting Eric Auger
2019-07-11 13:56 ` [PATCH v9 09/11] vfio/pci: Add framework for custom interrupt indices Eric Auger
2019-07-11 13:56 ` [PATCH v9 10/11] vfio/pci: Register and allow DMA FAULT IRQ signaling Eric Auger
2019-07-11 13:56 ` [PATCH v9 11/11] vfio: Document nested stage control Eric Auger
2019-07-12  7:38 ` [PATCH v9 00/11] SMMUv3 Nested Stage Setup (VFIO part) zhangfei.gao

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