From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: [PATCH] vfio/pci: make MSI handling optional Date: Thu, 09 Oct 2014 10:40:07 +0200 Message-ID: <6188781.C8VgeYvZpD@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: kvm@vger.kernel.org, Gavin Shan , Wen Xiong , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Alex Williamson Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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 Fixes: b8f02af096b1 ("vfio/pci: Restore MSIx message prior to enabling") --- 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: