Re: [PATCH 3/3] VFIO V4: VFIO driver: Non-privileged user level PCI drivers

Alex Williamson
2010-09-27T20:46:32Z

On Wed, 2010-09-22 at 14:18 -0700, Tom Lyon wrote:
> +ssize_t vfio_mem_readwrite(
> + int write,
> + struct vfio_dev *vdev,
> + char __user *buf,
> + size_t count,
> + loff_t *ppos)
> +{
> + struct pci_dev *pdev = vdev->pdev;
> + resource_size_t end;
> + void __iomem *io;
> + loff_t pos;
> + int pci_space;
> +
> + pci_space = vfio_offset_to_pci_space(*ppos);
> + pos = vfio_offset_to_pci_offset(*ppos);
> +
> + if (!pci_resource_start(pdev, pci_space))
> + return -EINVAL;
> + end = pci_resource_len(pdev, pci_space);
> + if (vdev->barmap[pci_space] == NULL)
> + vdev->barmap[pci_space] = pci_iomap(pdev, pci_space, 0);
> + io = vdev->barmap[pci_space];
> +

So we do a pci_iomap, but never do corresponding pci_iounmap. This also
only works for the first 6 BARs since the ROM BAR needs pci_map_rom. I
wonder if we should be doing all the BAR mapping at open and unmap at
close so that we can fail if the device can't get basic resources. I
believe we should also be calling pci_request_regions in here somewhere.
Perhaps something like this:

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index a18e39a..d3886d9 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -85,6 +85,53 @@ static inline int overlap(int a1, int b1, int a2, int b2)
return !(b2 <= a1 || b1 <= a2);
}

+static int vfio_setup_pci(struct vfio_dev *vdev)
+{
+ int ret, bar;
+
+ ret = pci_enable_device(vdev->pdev);
+ if (ret)
+ return ret;
+
+ ret = pci_request_regions(vdev->pdev, "VFIO");
+ if (ret) {
+ pci_disable_device(vdev->pdev);
+ return ret;
+ }
+
+ for (bar = PCI_STD_RESOURCES; bar <= PCI_ROM_RESOURCE; bar++) {
+ if (!pci_resource_len(vdev->pdev, bar))
+ continue;
+ if (bar != PCI_ROM_RESOURCE) {
+ if (!pci_resource_start(vdev->pdev, bar))
+ continue;
+ vdev->barmap[bar] = pci_iomap(vdev->pdev, bar, 0);
+ } else {
+ size_t size;
+ vdev->barmap[bar] = pci_map_rom(vdev->pdev, &size);
+ }
+ }
+ return ret;
+}
+
+static void vfio_disable_pci(struct vfio_dev *vdev)
+{
+ int bar;
+
+ for (bar = PCI_STD_RESOURCES; bar <= PCI_ROM_RESOURCE; bar++) {
+ if (!vdev->barmap[bar])
+ continue;
+ if (bar != PCI_ROM_RESOURCE)
+ pci_iounmap(vdev->pdev, vdev->barmap[bar]);
+ else
+ pci_unmap_rom(vdev->pdev, vdev->barmap[bar]);
+ vdev->barmap[bar] = NULL;
+ }
+
+ pci_release_regions(vdev->pdev);
+ pci_disable_device(vdev->pdev);
+}
+
static int vfio_open(struct inode *inode, struct file *filep)
{
struct vfio_dev *vdev;
@@ -110,7 +157,7 @@ static int vfio_open(struct inode *inode, struct file *filep)
INIT_LIST_HEAD(&listener->dm_list);
filep->private_data = listener;
if (vdev->listeners == 0)
- ret = pci_enable_device(vdev->pdev);
+ ret = vfio_setup_pci(vdev);
if (ret == 0)
vdev->listeners++;
mutex_unlock(&vdev->lgate);
@@ -151,7 +198,7 @@ static int vfio_release(struct inode *inode, struct file *filep)
vdev->vconfig = NULL;
kfree(vdev->pci_config_map);
vdev->pci_config_map = NULL;
- pci_disable_device(vdev->pdev);
+ vfio_disable_pci(vdev);
vfio_domain_unset(vdev);
wake_up(&vdev->dev_idle_q);
}
diff --git a/drivers/vfio/vfio_rdwr.c b/drivers/vfio/vfio_rdwr.c
index 1fd50a6..7705b45 100644
--- a/drivers/vfio/vfio_rdwr.c
+++ b/drivers/vfio/vfio_rdwr.c
@@ -64,7 +64,7 @@ ssize_t vfio_io_readwrite(
if (pos + count > end)
return -EINVAL;
if (vdev->barmap[pci_space] == NULL)
- vdev->barmap[pci_space] = pci_iomap(pdev, pci_space, 0);
+ return -EINVAL;
io = vdev->barmap[pci_space];

while (count > 0) {
@@ -137,7 +137,12 @@ ssize_t vfio_mem_readwrite(
return -EINVAL;
end = pci_resource_len(pdev, pci_space);
if (vdev->barmap[pci_space] == NULL)
- vdev->barmap[pci_space] = pci_iomap(pdev, pci_space, 0);
+ return -EINVAL;
+ if (pci_space == PCI_ROM_RESOURCE) {
+ u32 rom = *(u32 *)(vdev->vconfig + PCI_ROM_ADDRESS);
+ if (!(rom & PCI_ROM_ADDRESS_ENABLE))
+ return -EINVAL;
+ }
io = vdev->barmap[pci_space];

if (pos > end)