[PATCH v13 13/13] vfio/pci: Inject page response upon response region fill

Eric Auger
2021-04-11T11:50:13Z

When the userspace increments the head of the page response
buffer ring, let's push the response into the iommu layer.
This is done through a workqueue that pops the responses from
the ring buffer and increment the tail.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
---
drivers/vfio/pci/vfio_pci.c | 40 +++++++++++++++++++++++++++++
drivers/vfio/pci/vfio_pci_private.h | 7 +++++
drivers/vfio/pci/vfio_pci_rdwr.c | 1 +
3 files changed, 48 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 560b1a830726..bb4a0e1e39bf 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -552,6 +552,32 @@ static int vfio_pci_dma_fault_init(struct vfio_pci_device *vdev)
return ret;
}

+static void dma_response_inject(struct work_struct *work)
+{
+ struct vfio_pci_dma_fault_response_work *rwork =
+ container_of(work, struct vfio_pci_dma_fault_response_work, inject);
+ struct vfio_region_dma_fault_response *header = rwork->header;
+ struct vfio_pci_device *vdev = rwork->vdev;
+ struct iommu_page_response *resp;
+ u32 tail, head, size;
+
+ mutex_lock(&vdev->fault_response_queue_lock);
+
+ tail = header->tail;
+ head = header->head;
+ size = header->nb_entries;
+
+ while (CIRC_CNT(head, tail, size) >= 1) {
+ resp = (struct iommu_page_response *)(vdev->fault_response_pages + header->offset +
+ tail * header->entry_size);
+
+ /* TODO: properly handle the return value */
+ iommu_page_response(&vdev->pdev->dev, resp);
+ header->tail = tail = (tail + 1) % size;
+ }
+ mutex_unlock(&vdev->fault_response_queue_lock);
+}
+
#define DMA_FAULT_RESPONSE_RING_LENGTH 512

static int vfio_pci_dma_fault_response_init(struct vfio_pci_device *vdev)
@@ -597,8 +623,22 @@ static int vfio_pci_dma_fault_response_init(struct vfio_pci_device *vdev)
header->nb_entries = DMA_FAULT_RESPONSE_RING_LENGTH;
header->offset = PAGE_SIZE;

+ vdev->response_work = kzalloc(sizeof(*vdev->response_work), GFP_KERNEL);
+ if (!vdev->response_work)
+ goto out;
+ vdev->response_work->header = header;
+ vdev->response_work->vdev = vdev;
+
+ /* launch the thread that will extract the response */
+ INIT_WORK(&vdev->response_work->inject, dma_response_inject);
+ vdev->dma_fault_response_wq =
+ create_singlethread_workqueue("vfio-dma-fault-response");
+ if (!vdev->dma_fault_response_wq)
+ return -ENOMEM;
+
return 0;
out:
+ kfree(vdev->fault_response_pages);
vdev->fault_response_pages = NULL;
return ret;
}
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index f7b1e7fb86e5..835fbb221dea 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -52,6 +52,12 @@ struct vfio_pci_irq_ctx {
struct irq_bypass_producer producer;
};

+struct vfio_pci_dma_fault_response_work {
+ struct work_struct inject;
+ struct vfio_region_dma_fault_response *header;
+ struct vfio_pci_device *vdev;
+};
+
struct vfio_pci_device;
struct vfio_pci_region;

@@ -146,6 +152,7 @@ struct vfio_pci_device {
u8 *fault_pages;
u8 *fault_response_pages;
struct workqueue_struct *dma_fault_response_wq;
+ struct vfio_pci_dma_fault_response_work *response_work;
struct mutex fault_queue_lock;
struct mutex fault_response_queue_lock;
struct list_head dummy_resources_list;
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index efde0793360b..78c494fe35cc 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -430,6 +430,7 @@ size_t vfio_pci_dma_fault_response_rw(struct vfio_pci_device *vdev, char __user
mutex_lock(&vdev->fault_response_queue_lock);
header->head = new_head;
mutex_unlock(&vdev->fault_response_queue_lock);
+ queue_work(vdev->dma_fault_response_wq, &vdev->response_work->inject);
} else {
if (copy_to_user(buf, base + pos, count))
return -EFAULT;
--
2.26.3