On Mon, 2014-03-31 at 00:28 -0400, Bandan Das wrote:
> While using the new_id interface, the user can unintentionally feed
> incorrect values if the driver static table has a matching entry.
> This is possible since only the device and vendor fields are
> mandatory and the rest are optional. As a result, store_new_id
> will fill in default values that are then passed on to the driver
> and can have unintended consequences.
>
> As an example, consider the ixgbe driver and the 82599EB network card :
> echo "8086 10fb" > /sys/bus/pci/drivers/ixgbe/new_id
>
> This will pass a driver_data value of 0 to the driver whereas
> the index 0 in ixgbe actually points to a different set of card
> operations.
>
> This change automatically selects the matching static entry if there
> is one for the newly created dynid. However, if the user intentionally
> wants a different set of values, she must provide all the 7 fields
> and the static entry will be ignored.
>
> In most cases, this use case seems unnecessary, however, this
> is a common libvirt/KVM/device assignment scenario where the
> user might want to bind a device back to the host driver.
>
> Signed-off-by: Bandan Das <bsd@xxxxxxxxxx>
> ---
> drivers/pci/pci-driver.c | 42 ++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index 25f0bc6..187e572 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -90,6 +90,24 @@ static void pci_free_dynids(struct pci_driver *drv)
> spin_unlock(&drv->dynids.lock);
> }
>
> +static const struct
> +pci_device_id *match_id_table_entry(struct device_driver *driver,
> + __u32 vendor, __u32 device)
> +{
> + struct pci_driver *pdrv = to_pci_driver(driver);
> + const struct pci_device_id *ids = pdrv->id_table;
> +
> + if (ids) {
> + while (ids->vendor || ids->subvendor || ids->class_mask) {
> + if ((ids->vendor == vendor) && (ids->device == device))
> + return ids;
> + ids++;
> + }
> + }
> +
> + return NULL;
> +}
> +
> /**
> * store_new_id - sysfs frontend to pci_add_dynid()
> * @driver: target device driver
> @@ -102,7 +120,8 @@ static ssize_t
> store_new_id(struct device_driver *driver, const char *buf, size_t count)
> {
> struct pci_driver *pdrv = to_pci_driver(driver);
> - const struct pci_device_id *ids = pdrv->id_table;
> + const struct pci_device_id *ids = pdrv->id_table,
> + *tids = NULL;
> __u32 vendor, device, subvendor=PCI_ANY_ID,
> subdevice=PCI_ANY_ID, class=0, class_mask=0;
> unsigned long driver_data=0;
> @@ -115,9 +134,24 @@ store_new_id(struct device_driver *driver, const char *buf, size_t count)
> if (fields < 2)
> return -EINVAL;
>
> - /* Only accept driver_data values that match an existing id_table
> - entry */
> - if (ids) {
> + tids = match_id_table_entry(driver, vendor, device);
> +
Would it make more sense to construct a pci_dev, ex:
if (fields != 7) {
struct pci_dev dev = { .subvendor = PCI_ANY_ID, .subdevice = PCI_ANY_ID };
dev.vendor = vendor;
dev.device = device;
if (fields > 2)
dev.subvendor = subvendor;
if (fields > 3)
dev.subdevice = subdevice;
...
if (pci_match_id(drv->id_table, &dev))
return -EEXIST;
}
> + if (tids && (fields != 7)) {
> +
> + subvendor = tids->subvendor;
> + subdevice = tids->subdevice;
> + class = tids->class;
> + class_mask = tids->class_mask;
> + driver_data = tids->driver_data;
This doesn't look right. First, we're potentially overwriting user
stored data for fields >2 but <7. Second, we only matched on vendor &
device and could be filling the rest with data that isn't the best match
(and is guaranteed to just be a duplicate of a static table ID).
> +
> + pr_warn("pci: Using driver (%s) static DeviceID table entry for vendor 0x%04x and device 0x%04x",
> + driver->name, vendor, device);
I think we should be error'ing rather than inventing a duplicate ID to
insert. How would a user ever know how to use remove_id to clean out
this new_id? Thanks,
Alex
> +
> + } else if (ids) {
> +
> + /* Only accept driver_data values that match an existing
> + id_table entry */
> +
> retval = -EINVAL;
> while (ids->vendor || ids->subvendor || ids->class_mask) {
> if (driver_data == ids->driver_data) {
--
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