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Subject[PATCH v5 19/22] vfio-pci: Register an iommu fault handler
Date
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>

---

v3 -> v4:
- move iommu_unregister_device_fault_handler to vfio_pci_release
---
drivers/vfio/pci/vfio_pci.c | 49 +++++++++++++++++++++++++++++
drivers/vfio/pci/vfio_pci_private.h | 1 +
2 files changed, 50 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 01b1b4cb8349..cf12204486c3 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"

@@ -295,6 +296,46 @@ static const struct vfio_pci_regops vfio_pci_fault_prod_regops = {
.add_capability = vfio_pci_fault_prod_add_capability,
};

+int vfio_pci_iommu_dev_fault_handler(struct iommu_fault_event *evt, void *data)
+{
+ struct vfio_pci_device *vdev = (struct vfio_pci_device *) data;
+ struct vfio_region_fault_prod *prod_region =
+ (struct vfio_region_fault_prod *)vdev->fault_pages;
+ struct vfio_region_fault_cons *cons_region =
+ (struct vfio_region_fault_cons *)(vdev->fault_pages + 2 * PAGE_SIZE);
+ struct iommu_fault *new =
+ (struct iommu_fault *)(vdev->fault_pages + prod_region->offset +
+ prod_region->prod * prod_region->entry_size);
+ int prod, cons, size;
+
+ mutex_lock(&vdev->fault_queue_lock);
+
+ if (!vdev->fault_abi)
+ goto unlock;
+
+ prod = prod_region->prod;
+ cons = cons_region->cons;
+ size = prod_region->nb_entries;
+
+ if (CIRC_SPACE(prod, cons, size) < 1)
+ goto unlock;
+
+ *new = evt->fault;
+ prod = (prod + 1) % size;
+ prod_region->prod = prod;
+ mutex_unlock(&vdev->fault_queue_lock);
+
+ mutex_lock(&vdev->igate);
+ if (vdev->dma_fault_trigger)
+ eventfd_signal(vdev->dma_fault_trigger, 1);
+ mutex_unlock(&vdev->igate);
+ return 0;
+
+unlock:
+ mutex_unlock(&vdev->fault_queue_lock);
+ return -EINVAL;
+}
+
static int vfio_pci_init_fault_region(struct vfio_pci_device *vdev)
{
struct vfio_region_fault_prod *header;
@@ -327,6 +368,13 @@ static int vfio_pci_init_fault_region(struct vfio_pci_device *vdev)
header = (struct vfio_region_fault_prod *)vdev->fault_pages;
header->version = -1;
header->offset = PAGE_SIZE;
+
+ 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);
@@ -574,6 +622,7 @@ static void vfio_pci_release(void *device_data)
if (!(--vdev->refcnt)) {
vfio_spapr_pci_eeh_release(vdev->pdev);
vfio_pci_disable(vdev);
+ iommu_unregister_device_fault_handler(&vdev->pdev->dev);
}

mutex_unlock(&vdev->reflck->lock);
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 8e0a55682d3f..a9276926f008 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -122,6 +122,7 @@ struct vfio_pci_device {
int ioeventfds_nr;
struct eventfd_ctx *err_trigger;
struct eventfd_ctx *req_trigger;
+ struct eventfd_ctx *dma_fault_trigger;
struct mutex fault_queue_lock;
int fault_abi;
struct list_head dummy_resources_list;
--
2.20.1
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