[RFC v3 19/21] vfio-pci: Register an iommu fault handler

Eric Auger
2019-01-08T10:26:31Z

This patch registers a fault handler which records faults in
a circular buffer and then signals an eventfd. This buffer is
exposed within the fault region.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
drivers/vfio/pci/vfio_pci.c | 44 ++++++++++++++++++++++++++++-
drivers/vfio/pci/vfio_pci_private.h | 1 +
2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 2ba181ab2edd..f9e2c8292e60 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -29,6 +29,7 @@
#include <linux/vfio.h>
#include <linux/vgaarb.h>
#include <linux/nospec.h>
+#include <linux/circ_buf.h>

#include "vfio_pci_private.h"

@@ -1296,6 +1297,44 @@ static const struct vfio_pci_regops vfio_pci_dma_fault_regops = {
.release = vfio_pci_dma_fault_release,
};

+int vfio_pci_iommu_dev_fault_handler(struct iommu_fault_event *evt, void *data)
+{
+ struct vfio_pci_device *vdev = (struct vfio_pci_device *) data;
+ int prod, cons, size;
+ unsigned long flags;
+
+ spin_lock_irqsave(&vdev->fault_queue_lock, flags);
+ prod = vdev->fault_region->header.prod;
+ cons = vdev->fault_region->header.cons;
+ size = vdev->fault_region->header.size;
+
+ if (cons > VFIO_FAULT_QUEUE_SIZE - 1)
+ goto unlock;
+ if (prod > VFIO_FAULT_QUEUE_SIZE - 1)
+ goto unlock;
+ if (size != VFIO_FAULT_QUEUE_SIZE)
+ goto unlock;
+ if (vdev->fault_region->header.reserved)
+ goto unlock;
+ if (CIRC_SPACE(prod, cons, size) < 1)
+ goto unlock;
+
+ vdev->fault_region->queue[prod] = evt->fault;
+ prod = (prod + 1) % size;
+ vdev->fault_region->header.prod = prod;
+ spin_unlock_irqrestore(&vdev->fault_queue_lock, flags);
+
+ mutex_lock(&vdev->igate);
+ if (vdev->dma_fault_trigger)
+ eventfd_signal(vdev->dma_fault_trigger, 1);
+ mutex_unlock(&vdev->igate);
+ return 0;
+
+unlock:
+ spin_unlock_irqrestore(&vdev->fault_queue_lock, flags);
+ return -EINVAL;
+}
+
static int vfio_pci_init_dma_fault_region(struct vfio_pci_device *vdev)
{
u32 flags = VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE |
@@ -1322,7 +1361,9 @@ static int vfio_pci_init_dma_fault_region(struct vfio_pci_device *vdev)
vdev->fault_region->header.cons = 0;
vdev->fault_region->header.reserved = 0;
vdev->fault_region->header.size = VFIO_FAULT_QUEUE_SIZE;
- return 0;
+ return iommu_register_device_fault_handler(&vdev->pdev->dev,
+ vfio_pci_iommu_dev_fault_handler,
+ vdev);
}

static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
@@ -1414,6 +1455,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)

vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
kfree(vdev->region);
+ iommu_unregister_device_fault_handler(&pdev->dev);
kfree(vdev->fault_region);
mutex_destroy(&vdev->ioeventfds_lock);
kfree(vdev);
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 38b5d1764a26..5936802cbbd0 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -120,6 +120,7 @@ struct vfio_pci_device {
int ioeventfds_nr;
struct eventfd_ctx *err_trigger;
struct eventfd_ctx *req_trigger;
+ struct eventfd_ctx *dma_fault_trigger;
spinlock_t fault_queue_lock;
struct vfio_fault_region *fault_region;
struct list_head dummy_resources_list;
--
2.17.2