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SubjectRe: [PATCH 1/5] vfio-pci: Allow PCI IDs to be specified as module options
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On Fri, 2015-03-06 at 16:11 -0600, Bjorn Helgaas wrote:
> On Wed, Mar 04, 2015 at 01:02:43PM -0700, Alex Williamson wrote:
> > This copies the same support from pci-stub for exactly the same
> > purpose, enabling a set of PCI IDs to be automatically added to the
> > driver's dynamic ID table at module load time. The code here is
> > pretty simple and both vfio-pci and pci-stub are fairly unique in
> > being meta drivers, capable of attaching to any device, so there's no
> > attempt made to generalize the code into pci-core.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> > drivers/vfio/pci/vfio_pci.c | 46 +++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 46 insertions(+)
> >
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index f8a1863..b3bae4c 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -32,6 +32,10 @@
> > #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>"
> > #define DRIVER_DESC "VFIO PCI - User Level meta-driver"
> >
> > +static char ids[1024] __initdata;
> > +module_param_string(ids, ids, sizeof(ids), 0);
> > +MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the vfio driver, format is \"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\" and multiple comma separated entries can be specified");
> > +
> > static bool nointxmask;
> > module_param_named(nointxmask, nointxmask, bool, S_IRUGO | S_IWUSR);
> > MODULE_PARM_DESC(nointxmask,
> > @@ -1034,6 +1038,46 @@ static void __exit vfio_pci_cleanup(void)
> > vfio_pci_uninit_perm_bits();
> > }
> >
> > +static void __init vfio_pci_fill_ids(void)
> > +{
> > + char *p, *id;
> > + int rc;
> > +
> > + /* no ids passed actually */
> > + if (ids[0] == '\0')
> > + return;
> > +
> > + /* add ids specified in the module parameter */
> > + p = ids;
> > + while ((id = strsep(&p, ","))) {
> > + unsigned int vendor, device, subvendor = PCI_ANY_ID,
> > + subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
> > + int fields;
> > +
> > + if (!strlen(id))
> > + continue;
> > +
> > + fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
> > + &vendor, &device, &subvendor, &subdevice,
> > + &class, &class_mask);
> > +
> > + if (fields < 2) {
> > + pr_warn("vfio-pci: invalid id string \"%s\"\n", id);
> > + continue;
> > + }
> > +
> > + pr_info("vfio-pci: add %04X:%04X sub=%04X:%04X cls=%08X/%08X\n",
>
> pci_setup_device() uses "[%04x:%04x] ... class %#08x". Maybe they should
> be the same, at least as far as using upper/lower case, spelling out
> "class", and "0x" prefix. Maybe there's other precedent that you're
> following and pci_setup_device() is not?

Sorry for not responding to this right away. The precedent I was
following is pci_stub_init(), but I don't know that it's any sort of
canonical reference. PCI output in dmesg seems pretty consistent in
using lower case hex, so I agree we should make that change. I also
note that the default value for sub IDs is PCI_ANY_ID, which ends up
getting printed as 8 characters since we don't specify the length. I'm
also not a fan of the lack of consistency in printing the ID vs the sub
ID nor how the line wraps in dmesg w/ timestamps enabled. What do you
think about this:

[%04hx:%04hx[%04hx:%04hx]] class %#08x/%08x

Which gives us this and doesn't wrap:

[ 92.731809] vfio_pci: add [10de:11fa[ffff:ffff]] class 0x000000/00000000
[ 92.738530] vfio_pci: add [10de:0e0b[ffff:ffff]] class 0x000000/00000000

I'm open to adding 0x on the class mask as well if anyone wants it.
Thanks,
Alex

> > + vendor, device, subvendor, subdevice,
> > + class, class_mask);
> > +
> > + rc = pci_add_dynid(&vfio_pci_driver, vendor, device,
> > + subvendor, subdevice, class, class_mask, 0);
> > + if (rc)
> > + pr_warn("vfio-pci: failed to add dynamic id (%d)\n",
> > + rc);
> > + }
> > +}
> > +
> > static int __init vfio_pci_init(void)
> > {
> > int ret;
> > @@ -1053,6 +1097,8 @@ static int __init vfio_pci_init(void)
> > if (ret)
> > goto out_driver;
> >
> > + vfio_pci_fill_ids();
> > +
> > return 0;
> >
> > out_driver:
> >
> > --
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