On Thu, Jun 04, 2015 at 04:20:45PM +0100, Andre Przywara wrote: > In PCI config space there is an interrupt line field (offset 0x3f), > which is used to initially communicate the IRQ line number from > firmware to the OS. _Hardware_ should never use this information, > as the OS is free to write any information in there. > But kvmtool uses this number when it triggers IRQs in the guest, > which fails starting with Linux 3.19-rc1, where the PCI layer starts > writing the virtual IRQ number in there. > > Fix that by storing the IRQ number in a separate field in > struct virtio_pci, which is independent from the PCI config space > and cannot be influenced by the guest. > This fixes ARM/ARM64 guests using PCI with newer kernels. > > Signed-off-by: Andre Przywara <[email protected]> > --- > include/kvm/virtio-pci.h | 8 ++++++++ > virtio/pci.c | 9 ++++++--- > 2 files changed, 14 insertions(+), 3 deletions(-) > > diff --git a/include/kvm/virtio-pci.h b/include/kvm/virtio-pci.h > index c795ce7..b70cadd 100644 > --- a/include/kvm/virtio-pci.h > +++ b/include/kvm/virtio-pci.h > @@ -30,6 +30,14 @@ struct virtio_pci { > u8 isr; > u32 features; > > + /* > + * We cannot rely on the INTERRUPT_LINE byte in the config space once > + * we have run guest code, as the OS is allowed to use that field > + * as a scratch pad to communicate between driver and PCI layer. > + * So store our legacy interrupt line number in here for internal use. > + */ > + u8 legacy_irq_line; > + > /* MSI-X */ > u16 config_vector; > u32 config_gsi; > diff --git a/virtio/pci.c b/virtio/pci.c > index 7556239..e17e5a9 100644 > --- a/virtio/pci.c > +++ b/virtio/pci.c > @@ -141,7 +141,7 @@ static bool virtio_pci__io_in(struct ioport *ioport, > struct kvm_cpu *vcpu, u16 p > break; > case VIRTIO_PCI_ISR: > ioport__write8(data, vpci->isr); > - kvm__irq_line(kvm, vpci->pci_hdr.irq_line, VIRTIO_IRQ_LOW); > + kvm__irq_line(kvm, vpci->legacy_irq_line, VIRTIO_IRQ_LOW); > vpci->isr = VIRTIO_IRQ_LOW; > break; > default: > @@ -299,7 +299,7 @@ int virtio_pci__signal_vq(struct kvm *kvm, struct > virtio_device *vdev, u32 vq) > kvm__irq_trigger(kvm, vpci->gsis[vq]); > } else { > vpci->isr = VIRTIO_IRQ_HIGH; > - kvm__irq_trigger(kvm, vpci->pci_hdr.irq_line); > + kvm__irq_trigger(kvm, vpci->legacy_irq_line); > } > return 0; > } > @@ -323,7 +323,7 @@ int virtio_pci__signal_config(struct kvm *kvm, struct > virtio_device *vdev) > kvm__irq_trigger(kvm, vpci->config_gsi); > } else { > vpci->isr = VIRTIO_PCI_ISR_CONFIG; > - kvm__irq_trigger(kvm, vpci->pci_hdr.irq_line); > + kvm__irq_trigger(kvm, vpci->legacy_irq_line); > } > > return 0; > @@ -422,6 +422,9 @@ int virtio_pci__init(struct kvm *kvm, void *dev, struct > virtio_device *vdev, > if (r < 0) > goto free_msix_mmio; > > + /* save the IRQ that device__register() has allocated */ > + vpci->legacy_irq_line = vpci->pci_hdr.irq_line;
I'd rather we used the container_of trick that we do for virtio-mmio devices when assigning the irq in device__register. Then we can avoid this line completely. Will -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
