2021-02-23 21:22:16

by Auger Eric

[permalink] [raw]
Subject: [PATCH v12 13/13] vfio/pci: Inject page response upon response region fill

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 <[email protected]>
---
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 9f1f5008e556..a41497779a68 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 82a883c101c9..5944f96ced0c 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;
--
2.26.2