Re: [PATCH v10 04/11] vfio/pci: Add VFIO_REGION_TYPE_NESTED region type
From: Zenghui Yu
Date: Thu Sep 24 2020 - 04:23:23 EST
Hi Eric,
On 2020/3/21 0:19, Eric Auger wrote:
Add a new specific DMA_FAULT region aiming to exposed nested mode
translation faults.
The region has a ring buffer that contains the actual fault
records plus a header allowing to handle it (tail/head indices,
max capacity, entry size). At the moment the region is dimensionned
for 512 fault records.
Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
[...]
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 379a02c36e37..586b89debed5 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -260,6 +260,69 @@ int vfio_pci_set_power_state(struct vfio_pci_device *vdev, pci_power_t state)
return ret;
}
+static void vfio_pci_dma_fault_release(struct vfio_pci_device *vdev,
+ struct vfio_pci_region *region)
+{
+}
+
+static int vfio_pci_dma_fault_add_capability(struct vfio_pci_device *vdev,
+ struct vfio_pci_region *region,
+ struct vfio_info_cap *caps)
+{
+ struct vfio_region_info_cap_fault cap = {
+ .header.id = VFIO_REGION_INFO_CAP_DMA_FAULT,
+ .header.version = 1,
+ .version = 1,
+ };
+ return vfio_info_add_capability(caps, &cap.header, sizeof(cap));
+}
+
+static const struct vfio_pci_regops vfio_pci_dma_fault_regops = {
+ .rw = vfio_pci_dma_fault_rw,
+ .release = vfio_pci_dma_fault_release,
+ .add_capability = vfio_pci_dma_fault_add_capability,
+};
+
+#define DMA_FAULT_RING_LENGTH 512
+
+static int vfio_pci_init_dma_fault_region(struct vfio_pci_device *vdev)
+{
+ struct vfio_region_dma_fault *header;
+ size_t size;
+ int ret;
+
+ mutex_init(&vdev->fault_queue_lock);
+
+ /*
+ * We provision 1 page for the header and space for
+ * DMA_FAULT_RING_LENGTH fault records in the ring buffer.
+ */
+ size = ALIGN(sizeof(struct iommu_fault) *
+ DMA_FAULT_RING_LENGTH, PAGE_SIZE) + PAGE_SIZE;
+
+ vdev->fault_pages = kzalloc(size, GFP_KERNEL);
+ if (!vdev->fault_pages)
+ return -ENOMEM;
+
+ ret = vfio_pci_register_dev_region(vdev,
+ VFIO_REGION_TYPE_NESTED,
+ VFIO_REGION_SUBTYPE_NESTED_DMA_FAULT,
+ &vfio_pci_dma_fault_regops, size,
+ VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE,
+ vdev->fault_pages);
+ if (ret)
+ goto out;
+
+ header = (struct vfio_region_dma_fault *)vdev->fault_pages;
+ header->entry_size = sizeof(struct iommu_fault);
+ header->nb_entries = DMA_FAULT_RING_LENGTH;
+ header->offset = sizeof(struct vfio_region_dma_fault);
+ return 0;
+out:
+ kfree(vdev->fault_pages);
+ return ret;
+}
+
static int vfio_pci_enable(struct vfio_pci_device *vdev)
{
struct pci_dev *pdev = vdev->pdev;
@@ -358,6 +421,10 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
}
}
+ ret = vfio_pci_init_dma_fault_region(vdev);
+ if (ret)
+ goto disable_exit;
+
vfio_pci_probe_mmaps(vdev);
return 0;
@@ -1383,6 +1450,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
kfree(vdev->region);
+ kfree(vdev->fault_pages);
mutex_destroy(&vdev->ioeventfds_lock);
if (!disable_idle_d3)
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 8a2c7607d513..a392f50e3a99 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -119,6 +119,8 @@ struct vfio_pci_device {
int ioeventfds_nr;
struct eventfd_ctx *err_trigger;
struct eventfd_ctx *req_trigger;
+ u8 *fault_pages;
What's the reason to use 'u8'? It doesn't match the type of header, nor
the type of ring buffer.
+ struct mutex fault_queue_lock;
struct list_head dummy_resources_list;
struct mutex ioeventfds_lock;
struct list_head ioeventfds_list;
@@ -150,6 +152,14 @@ extern ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char __user *buf,
extern long vfio_pci_ioeventfd(struct vfio_pci_device *vdev, loff_t offset,
uint64_t data, int count, int fd);
+struct vfio_pci_fault_abi {
+ u32 entry_size;
+};
This is not used by this patch (and the whole series).
+
+extern size_t vfio_pci_dma_fault_rw(struct vfio_pci_device *vdev,
+ char __user *buf, size_t count,
+ loff_t *ppos, bool iswrite);
+
extern int vfio_pci_init_perm_bits(void);
extern void vfio_pci_uninit_perm_bits(void);
diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index a87992892a9f..4004ab8cad0e 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -274,6 +274,51 @@ ssize_t vfio_pci_vga_rw(struct vfio_pci_device *vdev, char __user *buf,
return done;
}
+size_t vfio_pci_dma_fault_rw(struct vfio_pci_device *vdev, char __user *buf,
+ size_t count, loff_t *ppos, bool iswrite)
+{
+ unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
+ loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
+ void *base = vdev->region[i].data;
+ int ret = -EFAULT;
+
+ if (pos >= vdev->region[i].size)
+ return -EINVAL;
+
+ count = min(count, (size_t)(vdev->region[i].size - pos));
+
+ mutex_lock(&vdev->fault_queue_lock);
+
+ if (iswrite) {
+ struct vfio_region_dma_fault *header =
+ (struct vfio_region_dma_fault *)base;
+ u32 new_tail;
+
+ if (pos != 0 || count != 4) {
+ ret = -EINVAL;
+ goto unlock;
+ }
+
+ if (copy_from_user((void *)&new_tail, buf, count))
+ goto unlock;
+
+ if (new_tail > header->nb_entries) {
Maybe
new_tail >= header->nb_entries ?
+ ret = -EINVAL;
+ goto unlock;
+ }
+ header->tail = new_tail;
+ } else {
+ if (copy_to_user(buf, base + pos, count))
+ goto unlock;
+ }
+ *ppos += count;
+ ret = count;
+unlock:
+ mutex_unlock(&vdev->fault_queue_lock);
+ return ret;
+}
+
+
static int vfio_pci_ioeventfd_handler(void *opaque, void *unused)
{
struct vfio_pci_ioeventfd *ioeventfd = opaque;
Thanks,
Zenghui