On 2014/11/5 16:43, Eric Auger wrote: > On 10/27/2014 12:23 PM, Li Liu wrote: >> >> >> On 2014/10/27 17:37, Peter Maydell wrote: >>> On 25 October 2014 09:24, john.liuli <john.liuli@xxxxxxxxxx> wrote: >>>> To get the interrupt reason to support such VIRTIO_NET_F_STATUS >>>> features I add a new register offset VIRTIO_MMIO_ISRMEM which >>>> will help to establish a shared memory region between qemu and >>>> virtio-mmio device. Then the interrupt reason can be accessed by >>>> guest driver through this region. At the same time, the virtio-mmio >>>> dirver check this region to see irqfd is supported or not during >>>> the irq handler registration, and different handler will be assigned. >>> >>> If you want to add a new register you should probably propose >>> an update to the virtio spec. However, it seems to me it would >>> be better to get generic PCI/PCIe working on the ARM virt >>> board instead; then we can let virtio-mmio quietly fade away. >>> This has been on the todo list for ages (and there have been >>> RFC patches posted for plain PCI), it's just nobody's had time >>> to work on it. >>> >>> thanks >>> -- PMM >>> >> >> So you mean virtio-mmio will be replaced by PCI/PCIe on ARM at last? >> If so, let this patch go with the wind:). Thx. > > Hi, > > As a fix of current situation where ISR is only partially updated when > vhost-irqfd handles standard IRQ and waiting for PCI emuluation, > wouldn't it make sense to store ISR content on vhost driver side and > introduce ioctls to read/write it. When using vhost BE, virtio QEMU > device would use those ioctl to read/update the ISR content. On top of > that we would update the ISR in vhost before triggering the irqfd. If I > do not miss anything this would at least make things functional with irqfd. > > As a second step, we could try to introduce in-kernel emulation of > ISR/ACK to fix the performance issue related to going to user-side each > time ISR/ACK accesses are done. > > Do you think it is worth investigating this direction? > Hi, About this problem I have a talk with Li Liu. As MST said, we could use multiple GSI to support vhost-net with irqfd. And we have figured out a way to solve this problem. The method is as same as virtio-pci which is to assign multiple irqs for virtio-mmio. Also it can support multiqueue virtio-net on arm. Would you have a look at this method? Thank you very much. - virtio-mmio: support for multiple irqs http://www.spinics.net/lists/kernel/msg1858860.html Thanks, Shannon > Thank you in advance > > Best Regards > > Eric > > >> >> Li. >>> . >>> _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
