On Wed, 2014-10-01 at 11:11 +0200, Frank Blaschka wrote: > On Fri, Sep 26, 2014 at 01:59:40PM -0600, Alex Williamson wrote: > > On Fri, 2014-09-26 at 08:45 +0200, Frank Blaschka wrote: > > > On Wed, Sep 24, 2014 at 10:05:57AM -0600, Alex Williamson wrote: > > > > On Wed, 2014-09-24 at 10:47 +0200, Frank Blaschka wrote: > > > > > On Mon, Sep 22, 2014 at 02:47:31PM -0600, Alex Williamson wrote: > > > > > > On Fri, 2014-09-19 at 13:54 +0200, frank.blaschka@xxxxxxxxxx wrote: > > > > > > > This set of patches implements a vfio based solution for pci > > > > > > > pass-through on the s390 platform. The kernel stuff is pretty > > > > > > > much straight forward, but qemu needs more work. > > > > > > > > > > > > > > Most interesting patch is: > > > > > > > vfio: make vfio run on s390 platform > > > > > > > > > > > > > > I hope Alex & Alex can give me some guidance how to do the changes > > > > > > > in an appropriate way. After creating a separate iommmu address space > > > > > > > for each attached PCI device I can successfully run the vfio type1 > > > > > > > iommu. So If we could extend type1 not registering all guest memory > > > > > > > (see patch) I think we do not need a special vfio iommu for s390 > > > > > > > for the moment. > > > > > > > > > > > > > > The patches implement the base pass-through support. s390 specific > > > > > > > virtualization functions are currently not included. This would > > > > > > > be a second step after the base support is done. > > > > > > > > > > > > > > kernel patches apply to linux-kvm-next > > > > > > > > > > > > > > KVM: s390: Enable PCI instructions > > > > > > > iommu: add iommu for s390 platform > > > > > > > vfio: make vfio build on s390 > > > > > > > > > > > > > > qemu patches apply to qemu-master > > > > > > > > > > > > > > s390: Add PCI bus support > > > > > > > s390: implement pci instruction > > > > > > > vfio: make vfio run on s390 platform > > > > > > > > > > > > > > Thx for feedback and review comments > > > > > > > > > > > > Sending patches as attachments makes it difficult to comment inline. > > > > > > > > > > > Sorry, don't understand this. I sent every patch as separate email so > > > > > you can comment directly on the patch. What do you prefer? > > > > > > > > The patches in each email are showing up as attachments in my mail > > > > client. Is it just me? > > > > > > > > > > 2/6 > > > > > > - careful of the namespace as you're changing functions from static and > > > > > > exporting them > > > > > > - doesn't seem like functions need to be exported, just non-static to > > > > > > call from s390-iommu.c > > > > > > > > > > > Ok, will change this. > > > > > > > > > > > 6/6 > > > > > > - We shouldn't need to globally disable mmap, each VFIO region reports > > > > > > whether it supports mmap and vfio-pci on s390 should indicate mmap is > > > > > > not supported on the platform. > > > > > Yes, this is even better to let the kernel announce a BAR can not be > > > > > mmap'ed. Checking the kernel code I realized the BARs are valid for > > > > > mmap'ing but the s390 platform does simply not allow this. So I feal we > > > > > have to introduce a platform switch in kernel. How about this ... > > > > > > > > > > --- a/drivers/vfio/pci/vfio_pci.c > > > > > +++ b/drivers/vfio/pci/vfio_pci.c > > > > > @@ -377,9 +377,11 @@ static long vfio_pci_ioctl(void *device_ > > > > > > > > > > info.flags = VFIO_REGION_INFO_FLAG_READ | > > > > > VFIO_REGION_INFO_FLAG_WRITE; > > > > > +#ifndef CONFIG_S390 > > > > > if (pci_resource_flags(pdev, info.index) & > > > > > IORESOURCE_MEM && info.size >= PAGE_SIZE) > > > > > info.flags |= VFIO_REGION_INFO_FLAG_MMAP; > > > > > +#endif > > > > > break; > > > > > case VFIO_PCI_ROM_REGION_INDEX: > > > > > { > > > > > > > > Maybe pull it out into a function. Also, is there some capability or > > > > feature we can test rather than just the architecture? I'd prefer it to > > > > be excluded because of a platform feature that prevents it rather than > > > > the overall architecture itself. > > > > > > > > > > Ok, understand this. There is no capability of feature so I will go with > > > the function. > > > > > > > > > - INTx should be done the same way, the interrupt index for INTx should > > > > > > report 0 count. The current code likely doesn't handle this, but it > > > > > > should be easy to fix. > > > > > The current code is fine. Problem is the card reports an interrupt index > > > > > (PCI_INTERRUPT_PIN) but again the platform does not support INTx at all. > > > > > So we need a platform switch as well. > > > > > > > > Yep, let's try to do something consistent with the MMAP testing. > > > > > > > > > > Do you mean let the kernel announce this also? > > > > Yes, the kernel reports a count of 0 in vfio_irq_info when the interrupt > > type is not supported. We do this for MSI/X already, but it's assumed > > that INTx is always present since it's part of what most platforms would > > consider the minimal feature set. > > > > > > > > - s390_msix_notify() vs msix_notify() should be abstracted somewhere > > > > > > > > > > Platform does not have have an apic so there is nothing we could emulate > > > > > in qemu to make the existing msix_notify() work. > > > > > > > > > > > else. How would an emulated PCI device with MSI-X support work? > > > > > > - same for add_msi_route > > > > > Same here, we have to setup an adapter route due to the fact MSIX > > > > > notifications are delivered as adapter/thin IRQs on the platform. > > > > > > > > > > Any suggestion or idea how a better abstraction could look like? > > > > > > > > > > With all the platform constraints I was not able to find a suitable > > > > > emulated device. Remember s390: > > > > > - does not support IO BARs > > > > > - does not support INTx only MSIX > > > > > > > > What about MSI (non-X)? > > > > > > In theory MSI should work also but I have not seen in reality. > > > > > > > > > > > > - in reality currently there is only a PCI network card available > > > > > > > > On the physical hardware? > > > > > > > > > > yes > > > > > > > > - platform does not support fancy I/O like usb or audio :-) > > > > > So we don't even have kernel (host and guest) support for this > > > > > kind of devices. > > > > > > > > Does that mean you couldn't? What about virtio-net-pci with MSI-X > > > > interrupts or emulated xhci with MSI-X interrupts, couldn't those be > > > > supported if s390 MSI-X were properly integrated into the QEMU MSI-X > > > > API? vfio-pci isn't the right level to be switching between the > > > > standard API and the s390 API. > > > > > > > > > > Yes, I also think vfio might not be the best place to switch API. Will try > > > to move s390 specifics to MSI-X level. > > > > > > > > > - We can probably come up with a better way to determine which address > > > > > > space to connect to the memory listener. > > > > > Any suggestion or idea for that? > > > > > > > > I imagine you can tell by the address space of the device whether it > > > > lives behind an emulated IOMMU or not and therefore pick the closest > > > > address space for the notifier, the IOMMU or the system. Thanks, > > > > > > > > > > I do not undertand this in detail, can you elaborate a little bit more on this? > > > Or maybe provide a code snip? > > > > Well, I'm mostly making things up, but my assumption is that the device > > appears behind an IOMMU in the guest and by walking through address > > spaces from the device, we should be able to figure that out and avoid > > using a platform #ifdef. IOW, it's not s390 that makes us need to use a > > different address space, it's the guest topology of having an emulated > > IOMMU for the device, and that's what we should be keying on rather than > > the arch. Thanks, > > > > Do you think this would be sufficient? > > @@ -3689,8 +3701,13 @@ static int vfio_connect_container(VFIOGr > container->iommu_data.type1.listener = vfio_memory_listener; > container->iommu_data.release = vfio_listener_release; > > - memory_listener_register(&container->iommu_data.type1.listener, > - &address_space_memory); > + if (memory_region_is_iommu(as->root)) { > + memory_listener_register(&container->iommu_data.type1.listener, > + container->space->as); > + } else { > + memory_listener_register(&container->iommu_data.type1.listener, > + &address_space_memory); > + } > > if (container->iommu_data.type1.error) { > ret = container->iommu_data.type1.error; > > If not what else has to be checked? What are the indications to add the memory > listener to container address space or to address_space_memory? > Thx for your help. Sure, that's what I was asking for, but as I'm looking at is, shouldn't we be able to use container->space->as regardless? It seems like an oversight that address_space_memory wasn't replaced with container->space->as when Alexey added support for multiple address spaces. The container->space->as value comes from pci_device_iommu_address_space() which walks the PCI bus up from the device looking for an IOMMU address space. If it doesn't find one (likely) it uses address_space_memory. So I suspect if we fix the code, there's no need for any sort of switch. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html