On 10/25/16 20:24, Laszlo Ersek wrote: > Some systems have multiple instances of the exact same kind of PCI device > installed. When VFIO users intend to assign these devices to VMs, they > occasionally don't want to assign all of them; they'd keep a few for > host-side use. The current ID- and class-based matching in pci-stub > doesn't accommodate this use case, so users are left with either > rc.local-style host boot scripts, or QEMU wrapper scripts (which are > inferior to a pure libvirt environment). > > Introduce the "except" module parameter for pci-stub. In addition to > "ids", users can specify a list of Domain:Bus:Device.Function tuples. The > tuples are parsed and saved before pci_add_dynid() is called. The pci-stub > probe function will fail for the listed devices, for the initial and all > later (explicit) binding attempts. > > Cc: Alex Williamson <alex.william...@redhat.com> > Cc: Andrei Grigore <andrei....@gmail.com> > Cc: Bjorn Helgaas <bhelg...@google.com> > Cc: Jayme Howard <g.pr...@gmail.com> > Reported-by: Andrei Grigore <andrei....@gmail.com> > Ref: https://www.redhat.com/archives/vfio-users/2016-October/msg00121.html > Signed-off-by: Laszlo Ersek <ler...@redhat.com> > --- > drivers/pci/pci-stub.c | 63 > ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 63 insertions(+) > > diff --git a/drivers/pci/pci-stub.c b/drivers/pci/pci-stub.c > index 886fb3570278..120c29609c44 100644 > --- a/drivers/pci/pci-stub.c > +++ b/drivers/pci/pci-stub.c > @@ -26,8 +26,44 @@ MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the stub > driver, format is " > > "\"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\"" > " and multiple comma separated entries can be specified"); > > +#define MAX_EXCEPT 16 > + > +static unsigned num_except; > +static struct except { > + u16 domain; > + u16 devid; > +} except[MAX_EXCEPT]; > + > +/* > + * Accommodate substrings like "0000:00:1c.4," MAX_EXCEPT times, with the > comma > + * replaced with '\0' in the last instance > + */ > +static char except_str[13 * MAX_EXCEPT] __initdata; > + > +module_param_string(except, except_str, sizeof except_str, 0); > +MODULE_PARM_DESC(except, "Comma-separated list of PCI addresses to except " > + "from the ID- and class-based binding. The address format is " > + "Domain:Bus:Device.Function (all components are required and " > + "written in hex), for example, 0000:00:1c.4. At most " > + __stringify(MAX_EXCEPT) " exceptions are supported."); > + > +static inline bool exception_matches(const struct except *ex, > + const struct pci_dev *dev) > +{ > + return ex->domain == pci_domain_nr(dev->bus) && > + ex->devid == PCI_DEVID(dev->bus->number, dev->devfn); > +} > + > static int pci_stub_probe(struct pci_dev *dev, const struct pci_device_id > *id) > { > + unsigned i; > + > + for (i = 0; i < num_except; i++) > + if (exception_matches(&except[i], dev)) { > + dev_info(&dev->dev, "skipped by stub\n"); > + return -EPERM; > + } > + > dev_info(&dev->dev, "claimed by stub\n"); > return 0; > } > @@ -47,6 +83,33 @@ static int __init pci_stub_init(void) > if (rc) > return rc; > > + /* parse exceptions */ > + p = except_str; > + while ((id = strsep(&p, ","))) { > + int fields; > + unsigned domain, bus, dev, fn; > + > + if (*id == '\0') > + continue; > + > + fields = sscanf(id, "%x:%x:%x.%x", &domain, &bus, &dev, &fn); > + if (fields != 4 || domain > 0xffff || bus > 0xff || > + dev > 0x1f || fn > 0x7) { > + printk(KERN_WARNING > + "pci-stub: invalid exception \"%s\"\n", id); > + continue; > + } > + > + if (num_except < MAX_EXCEPT) { > + struct except *ex = &except[num_except++]; > + > + ex->domain = domain; > + ex->devid = PCI_DEVID(bus, PCI_DEVFN(dev, fn)); > + } else > + printk(KERN_WARNING > + "pci-stub: no room for exception \"%s\"\n", id); > + } > + > /* no ids passed actually */ > if (ids[0] == '\0') > return 0; >
Ping -- I don't "insist" on getting this patch in, but I'd like to see a clear decision about it. Leaving it hanging is terrible. Please follow up with a clear ACK, or a clear NAK, or advice for improving the patch. (Again, I don't mind if it gets nacked, but I'd like to see it explicitly.) (I think I responded to Alex's earlier points acceptably; IOW the ball shouldn't be in my court ATM.) Thanks Laszlo
