| Message ID | 6188781.C8VgeYvZpD@wuerfel (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 2014-10-09 at 10:40 +0200, Arnd Bergmann wrote: > A recent bug fix to the MSIx handling in vfio added references > to functions that may not be defined if MSI is disabled in the kernel, > resulting in this link error: > > drivers/built-in.o: In function `vfio_msi_set_vector_signal': > :(.text+0x450808): undefined reference to `get_cached_msi_msg' > :(.text+0x45080c): undefined reference to `write_msi_msg' > > From what I can tell, all the MSI specific ioctl handling can > be made optional in this case, which also reduces the code size > for the vfo driver. This patches does so using a build-time > IS_ENABLED() check, which leaves all the build coverage testing > present but avoids the link error. > > A side-effect of this is that the driver now returns -ENOTTY instead > of -EINVAL if user space calls VFIO_PCI_MSI_IRQ_INDEX on a kernel > without MSI support, which seems to be the best behavior, but > the approach could easily be changed if we want to preserve the > existing behavior for compatibility reasons. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") > --- Why wouldn't we handle this with stubs for `get_cached_msi_msg' and `write_msi_msg'? We're really not talking about much code that might get removed by the compiler with this static branch and and it seems like a rather non-standard mechanism. The count of MSI/X IRQs advertised to the user should be zero without CONFIG_MSI and later range checks would prevent calls to these functions for invalid indexes, so it's a bit of a random test in the code flow. Thanks, Alex > Found using randconfig build testing on ARM. > > diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c > index 553212f037c3..1117f96b8556 100644 > --- a/drivers/vfio/pci/vfio_pci_intrs.c > +++ b/drivers/vfio/pci/vfio_pci_intrs.c > @@ -827,6 +827,9 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags, > break; > case VFIO_PCI_MSI_IRQ_INDEX: > case VFIO_PCI_MSIX_IRQ_INDEX: > + if (!IS_ENABLED(CONFIG_PCI_MSI)) > + break; > + > switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) { > case VFIO_IRQ_SET_ACTION_MASK: > case VFIO_IRQ_SET_ACTION_UNMASK: > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday 13 October 2014 02:50:08 Alex Williamson wrote: > > Why wouldn't we handle this with stubs for `get_cached_msi_msg' and > `write_msi_msg'? We're really not talking about much code that might > get removed by the compiler with this static branch and and it seems > like a rather non-standard mechanism. The count of MSI/X IRQs > advertised to the user should be zero without CONFIG_MSI and later range > checks would prevent calls to > these functions for invalid indexes, so it's a bit of a random test in > the code flow. Thanks, > That's fine with me too. Arnd -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 553212f037c3..1117f96b8556 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -827,6 +827,9 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_device *vdev, uint32_t flags, break; case VFIO_PCI_MSI_IRQ_INDEX: case VFIO_PCI_MSIX_IRQ_INDEX: + if (!IS_ENABLED(CONFIG_PCI_MSI)) + break; + switch (flags & VFIO_IRQ_SET_ACTION_TYPE_MASK) { case VFIO_IRQ_SET_ACTION_MASK: case VFIO_IRQ_SET_ACTION_UNMASK:
A recent bug fix to the MSIx handling in vfio added references to functions that may not be defined if MSI is disabled in the kernel, resulting in this link error: drivers/built-in.o: In function `vfio_msi_set_vector_signal': :(.text+0x450808): undefined reference to `get_cached_msi_msg' :(.text+0x45080c): undefined reference to `write_msi_msg' From what I can tell, all the MSI specific ioctl handling can be made optional in this case, which also reduces the code size for the vfo driver. This patches does so using a build-time IS_ENABLED() check, which leaves all the build coverage testing present but avoids the link error. A side-effect of this is that the driver now returns -ENOTTY instead of -EINVAL if user space calls VFIO_PCI_MSI_IRQ_INDEX on a kernel without MSI support, which seems to be the best behavior, but the approach could easily be changed if we want to preserve the existing behavior for compatibility reasons. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") --- Found using randconfig build testing on ARM. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html