On Fri, 2013-06-21 at 11:56 +1000, Alexey Kardashevskiy wrote:
> On 06/21/2013 02:51 AM, Alex Williamson wrote:
> > On Fri, 2013-06-21 at 00:08 +1000, Alexey Kardashevskiy wrote:
> >> At the moment QEMU creates a route for every MSI IRQ.
> >>
> >> Now we are about to add IRQFD support on PPC64-pseries platform.
> >> pSeries already has in-kernel emulated interrupt controller with
> >> 8192 IRQs. Also, pSeries PHB already supports MSIMessage to IRQ
> >> mapping as a part of PAPR requirements for MSI/MSIX guests.
> >> Specifically, the pSeries guest does not touch MSIMessage's at
> >> all, instead it uses rtas_ibm_change_msi and
> >> rtas_ibm_query_interrupt_source
> >> rtas calls to do the mapping.
> >>
> >> Therefore we do not really need more routing than we got already.
> >> The patch introduces the infrastructure to enable direct IRQ mapping.
> >>
> >> Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
> >>
> >> ---
> >>
> >> The patch is raw and ugly indeed, I made it only to demonstrate
> >> the idea and see if it has right to live or not.
> >>
> >> For some reason which I do not really understand (limited GSI numbers?)
> >> the existing code always adds routing and I do not see why we would need
> >> it.
> >
> > It's an IOAPIC, a pin gets toggled from the device and an MSI message
> > gets written to the CPU. So the route allocates and programs the
> > pin->MSI, then we tell it what notifier triggers that pin.
>
> > On x86 the MSI vector doesn't encode any information about the device
> > sending the MSI, here you seem to be able to figure out the device and
> > vector space number from the address. Then your pin to MSI is
> > effectively fixed. So why isn't this just your
> > kvm_irqchip_add_msi_route function? On pSeries it's a lookup, on x86
> > it's a allocate and program.
> > What does kvm_irqchip_add_msi_route do on
> > pSeries today? Thanks,
>
>
> As we just started implementing this thing, I commented it out for the
> starter. Once called, it destroys direct mapping in the host kernel and
> everything stops working as routing is not implemented (yet? ever?).
Yay, it's broken, you can rewrite it ;)
> My point here is that MSIMessage to irq translation is made on a PCI domain
> as PAPR (ppc64 server) spec says. The guest never uses MSIMessage, it is
> all in QEMU, the guest dynamically allocates MSI IRQs and it is up to a
> hypeviser (QEMU) to take care of actual MSIMessage for the device.
MSIMessage is what the guest has programmed for the address/data fields,
it's not just a QEMU invention. From the guest perspective, the device
writes msg.data to msg.address to signal the CPU for the interrupt.
> And the only reason to use MSIMessage in QEMU for us is to support
> msi_notify()/msix_notify() in places like vfio_msi_interrupt(), I have
> added a MSI window for that long time ago which we do not need as much as
> we already have an irq number in vfio_msi_interrupt(), etc.
It seems like you just have another layer of indirection via your
msi_table. For x86 there's a layer of indirection via the virq virtual
IOAPIC pin. Seems similar. Thanks,
Alex
> >> ---
> >> hw/misc/vfio.c | 11 +++++++++--
> >> hw/pci/pci.c | 13 +++++++++++++
> >> hw/ppc/spapr_pci.c | 13 +++++++++++++
> >> hw/virtio/virtio-pci.c | 26 ++++++++++++++++++++------
> >> include/hw/pci/pci.h | 4 ++++
> >> include/hw/pci/pci_bus.h | 1 +
> >> 6 files changed, 60 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> >> index 14aac04..2d9eef7 100644
> >> --- a/hw/misc/vfio.c
> >> +++ b/hw/misc/vfio.c
> >> @@ -639,7 +639,11 @@ static int vfio_msix_vector_do_use(PCIDevice *pdev,
> >> unsigned int nr,
> >> * Attempt to enable route through KVM irqchip,
> >> * default to userspace handling if unavailable.
> >> */
> >> - vector->virq = msg ? kvm_irqchip_add_msi_route(kvm_state, *msg) : -1;
> >> +
> >> + vector->virq = msg ? pci_bus_map_msi(vdev->pdev.bus, *msg) : -1;
> >> + if (vector->virq < 0) {
> >> + vector->virq = msg ? kvm_irqchip_add_msi_route(kvm_state, *msg) :
> >> -1;
> >> + }
> >> if (vector->virq < 0 ||
> >> kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
> >> vector->virq) < 0) {
> >> @@ -807,7 +811,10 @@ retry:
> >> * Attempt to enable route through KVM irqchip,
> >> * default to userspace handling if unavailable.
> >> */
> >> - vector->virq = kvm_irqchip_add_msi_route(kvm_state, msg);
> >> + vector->virq = pci_bus_map_msi(vdev->pdev.bus, msg);
> >> + if (vector->virq < 0) {
> >> + vector->virq = kvm_irqchip_add_msi_route(kvm_state, msg);
> >> + }
> >> if (vector->virq < 0 ||
> >> kvm_irqchip_add_irqfd_notifier(kvm_state, &vector->interrupt,
> >> vector->virq) < 0) {
> >> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> >> index a976e46..a9875e9 100644
> >> --- a/hw/pci/pci.c
> >> +++ b/hw/pci/pci.c
> >> @@ -1254,6 +1254,19 @@ void pci_device_set_intx_routing_notifier(PCIDevice
> >> *dev,
> >> dev->intx_routing_notifier = notifier;
> >> }
> >>
> >> +void pci_bus_set_map_msi_fn(PCIBus *bus, pci_map_msi_fn map_msi_fn)
> >> +{
> >> + bus->map_msi = map_msi_fn;
> >> +}
> >> +
> >> +int pci_bus_map_msi(PCIBus *bus, MSIMessage msg)
> >> +{
> >> + if (bus->map_msi) {
> >> + return bus->map_msi(bus, msg);
> >> + }
> >> + return -1;
> >> +}
> >> +
> >> /*
> >> * PCI-to-PCI bridge specification
> >> * 9.1: Interrupt routing. Table 9-1
> >> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> >> index 80408c9..9ef9a29 100644
> >> --- a/hw/ppc/spapr_pci.c
> >> +++ b/hw/ppc/spapr_pci.c
> >> @@ -500,6 +500,18 @@ static void spapr_msi_write(void *opaque, hwaddr addr,
> >> qemu_irq_pulse(xics_get_qirq(spapr->icp, irq));
> >> }
> >>
> >> +static int spapr_msi_get_irq(PCIBus *bus, MSIMessage msg)
> >> +{
> >> + DeviceState *par = bus->qbus.parent;
> >> + sPAPRPHBState *sphb = (sPAPRPHBState *) par;
> >> + unsigned long addr = msg.address - sphb->msi_win_addr;
> >> + int ndev = addr >> 16;
> >> + int vec = ((addr & 0xFFFF) >> 2) | msg.data;
> >> + uint32_t irq = sphb->msi_table[ndev].irq + vec;
> >> +
> >> + return (int)irq;
> >> +}
> >> +
> >> static const MemoryRegionOps spapr_msi_ops = {
> >> /* There is no .read as the read result is undefined by PCI spec */
> >> .read = NULL,
> >> @@ -664,6 +676,7 @@ static int _spapr_phb_init(SysBusDevice *s)
> >>
> >> sphb->lsi_table[i].irq = irq;
> >> }
> >> + pci_bus_set_map_msi_fn(bus, spapr_msi_get_irq);
> >>
> >> return 0;
> >> }
> >> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> >> index d309416..587f53e 100644
> >> --- a/hw/virtio/virtio-pci.c
> >> +++ b/hw/virtio/virtio-pci.c
> >> @@ -472,6 +472,8 @@ static unsigned virtio_pci_get_features(DeviceState *d)
> >> return proxy->host_features;
> >> }
> >>
> >> +extern int spapr_msi_get_irq(PCIBus *bus, MSIMessage *msg);
> >> +
> >> static int kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
> >> unsigned int queue_no,
> >> unsigned int vector,
> >> @@ -481,7 +483,10 @@ static int
> >> kvm_virtio_pci_vq_vector_use(VirtIOPCIProxy *proxy,
> >> int ret;
> >>
> >> if (irqfd->users == 0) {
> >> - ret = kvm_irqchip_add_msi_route(kvm_state, msg);
> >> + ret = pci_bus_map_msi(proxy->pci_dev.bus, msg);
> >> + if (ret < 0) {
> >> + ret = kvm_irqchip_add_msi_route(kvm_state, msg);
> >> + }
> >> if (ret < 0) {
> >> return ret;
> >> }
> >> @@ -609,14 +614,23 @@ static int
> >> virtio_pci_vq_vector_unmask(VirtIOPCIProxy *proxy,
> >> VirtQueue *vq = virtio_get_queue(proxy->vdev, queue_no);
> >> EventNotifier *n = virtio_queue_get_guest_notifier(vq);
> >> VirtIOIRQFD *irqfd;
> >> - int ret = 0;
> >> + int ret = 0, tmp;
> >>
> >> if (proxy->vector_irqfd) {
> >> irqfd = &proxy->vector_irqfd[vector];
> >> - if (irqfd->msg.data != msg.data || irqfd->msg.address !=
> >> msg.address) {
> >> - ret = kvm_irqchip_update_msi_route(kvm_state, irqfd->virq,
> >> msg);
> >> - if (ret < 0) {
> >> - return ret;
> >> +
> >> + tmp = pci_bus_map_msi(proxy->pci_dev.bus, msg);
> >> + if (tmp >= 0) {
> >> + if (irqfd->virq != tmp) {
> >> + fprintf(stderr, "FIXME: MSI(-X) vector has changed from
> >> %X to %x\n",
> >> + irqfd->virq, tmp);
> >> + }
> >> + } else {
> >> + if (irqfd->msg.data != msg.data || irqfd->msg.address !=
> >> msg.address) {
> >> + ret = kvm_irqchip_update_msi_route(kvm_state,
> >> irqfd->virq, msg);
> >> + if (ret < 0) {
> >> + return ret;
> >> + }
> >> }
> >> }
> >> }
> >> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> >> index 8797802..632739a 100644
> >> --- a/include/hw/pci/pci.h
> >> +++ b/include/hw/pci/pci.h
> >> @@ -332,6 +332,7 @@ MemoryRegion *pci_address_space_io(PCIDevice *dev);
> >> typedef void (*pci_set_irq_fn)(void *opaque, int irq_num, int level);
> >> typedef int (*pci_map_irq_fn)(PCIDevice *pci_dev, int irq_num);
> >> typedef PCIINTxRoute (*pci_route_irq_fn)(void *opaque, int pin);
> >> +typedef int (*pci_map_msi_fn)(PCIBus *bus, MSIMessage msg);
> >>
> >> typedef enum {
> >> PCI_HOTPLUG_DISABLED,
> >> @@ -375,6 +376,9 @@ bool pci_intx_route_changed(PCIINTxRoute *old,
> >> PCIINTxRoute *new);
> >> void pci_bus_fire_intx_routing_notifier(PCIBus *bus);
> >> void pci_device_set_intx_routing_notifier(PCIDevice *dev,
> >> PCIINTxRoutingNotifier
> >> notifier);
> >> +void pci_bus_set_map_msi_fn(PCIBus *bus, pci_map_msi_fn map_msi_fn);
> >> +int pci_bus_map_msi(PCIBus *bus, MSIMessage msg);
> >> +
> >> void pci_device_reset(PCIDevice *dev);
> >> void pci_bus_reset(PCIBus *bus);
> >>
> >> diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
> >> index 66762f6..81efd2b 100644
> >> --- a/include/hw/pci/pci_bus.h
> >> +++ b/include/hw/pci/pci_bus.h
> >> @@ -16,6 +16,7 @@ struct PCIBus {
> >> pci_set_irq_fn set_irq;
> >> pci_map_irq_fn map_irq;
> >> pci_route_irq_fn route_intx_to_irq;
> >> + pci_map_msi_fn map_msi;
> >> pci_hotplug_fn hotplug;
> >> DeviceState *hotplug_qdev;
> >> void *irq_opaque;
> >
> >
> >
>
>
