On Mon, Oct 15, 2012 at 02:28:15PM -0600, Alex Williamson wrote:
> This makes use of the new level irqfd support enabling bypass of
> qemu userspace both on INTx injection and unmask. This significantly
> boosts the performance of devices making use of legacy interrupts.
>
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
>
> My INTx routing workaround below will probably raise some eyebrows,
> but I don't feel it's worth subjecting users to core dumps if they
> want to try vfio-pci on new platforms. INTx routing is part of some
> larger plan, but until that plan materializes we have to try to avoid
> the API unless we think there's a good chance it might be there.
> I'll accept the maintenance of updating a whitelist in the interim.
> Thanks,
>
> Alex
>
> hw/vfio_pci.c | 224 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 224 insertions(+)
>
> diff --git a/hw/vfio_pci.c b/hw/vfio_pci.c
> index 639371e..777a5f8 100644
> --- a/hw/vfio_pci.c
> +++ b/hw/vfio_pci.c
> @@ -154,6 +154,53 @@ static uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len);
> static void vfio_mmap_set_enabled(VFIODevice *vdev, bool enabled);
>
> /*
> + * PCI code refuses to make it possible to probe whether the chipset
> + * supports pci_device_route_intx_to_irq() and booby traps the call
> + * to assert if doesn't. For us, this is just an optimization, so
> + * only enable it when we know it's present. Unfortunately PCIBus is
> + * private, so we can't just look at the function pointer.
> + */
> +static bool vfio_pci_bus_has_intx_route(PCIDevice *pdev)
> +{
> +#ifdef CONFIG_KVM
> + BusState *bus = qdev_get_parent_bus(&pdev->qdev);
> + DeviceState *dev;
> +
> + if (!kvm_irqchip_in_kernel() ||
> + !kvm_check_extension(kvm_state, KVM_CAP_IRQFD_RESAMPLE)) {
> + return false;
> + }
Shouldn't we update linux-headers/ to get KVM_CAP_IRQFD_RESAMPLE?
Also for KVM_IRQFD_FLAG_RESAMPLE.
> +
> + for (; bus->parent; bus = qdev_get_parent_bus(dev)) {
> +
> + dev = bus->parent;
> +
> + if (!strncmp("i440FX-pcihost", object_get_typename(OBJECT(dev)), 14)) {
> + return true;
> + }
> + }
> +
> + error_report("vfio-pci: VM chipset does not support INTx routing, "
> + "using slow INTx mode\n");
When does this code trigger? It seems irqchip implies piix ATM -
is this just dead code?
> +#endif
> + return false;
> +}
> +
> +static PCIINTxRoute vfio_pci_device_route_intx_to_irq(PCIDevice *pdev, int pin)
> +{
> + if (!vfio_pci_bus_has_intx_route(pdev)) {
> + return (PCIINTxRoute) { .mode = PCI_INTX_DISABLED, .irq = -1 };
> + }
> +
> + return pci_device_route_intx_to_irq(pdev, pin);
> +}
> +
> +static bool vfio_pci_intx_route_changed(PCIINTxRoute *old, PCIINTxRoute *new)
> +{
> + return old->mode != new->mode || old->irq != new->irq;
> +}
> +
Didn't you add an API for this? It's on pci branch but I can drop
it if not needed.
> +/*
> * Common VFIO interrupt disable
> */
> static void vfio_disable_irqindex(VFIODevice *vdev, int index)
> @@ -185,6 +232,21 @@ static void vfio_unmask_intx(VFIODevice *vdev)
> ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, &irq_set);
> }
>
> +#ifdef CONFIG_KVM
> +static void vfio_mask_intx(VFIODevice *vdev)
> +{
> + struct vfio_irq_set irq_set = {
> + .argsz = sizeof(irq_set),
> + .flags = VFIO_IRQ_SET_DATA_NONE | VFIO_IRQ_SET_ACTION_MASK,
> + .index = VFIO_PCI_INTX_IRQ_INDEX,
> + .start = 0,
> + .count = 1,
> + };
> +
> + ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, &irq_set);
> +}
> +#endif
> +
> /*
> * Disabling BAR mmaping can be slow, but toggling it around INTx can
> * also be a huge overhead. We try to get the best of both worlds by
> @@ -248,6 +310,161 @@ static void vfio_eoi(VFIODevice *vdev)
> vfio_unmask_intx(vdev);
> }
>
> +static void vfio_enable_intx_kvm(VFIODevice *vdev)
> +{
> +#ifdef CONFIG_KVM
> + struct kvm_irqfd irqfd = {
> + .fd = event_notifier_get_fd(&vdev->intx.interrupt),
> + .gsi = vdev->intx.route.irq,
> + .flags = KVM_IRQFD_FLAG_RESAMPLE,
Should not kvm ioctl handling be localized in kvm-all.c?
E.g. extend kvm_irqchip_add_irqfd_notifier in
some way? Same question for KVM_CAP_IRQFD_RESAMPLE use above ...
> + };
> + struct vfio_irq_set *irq_set;
> + int ret, argsz;
> + int32_t *pfd;
> +
> + if (!kvm_irqchip_in_kernel() ||
> + vdev->intx.route.mode != PCI_INTX_ENABLED ||
> + !kvm_check_extension(kvm_state, KVM_CAP_IRQFD_RESAMPLE)) {
> + return;
> + }
> +
> + /* Get to a known interrupt state */
> + qemu_set_fd_handler(irqfd.fd, NULL, NULL, vdev);
> + vfio_mask_intx(vdev);
> + vdev->intx.pending = false;
> + qemu_set_irq(vdev->pdev.irq[vdev->intx.pin], 0);
> +
> + /* Get an eventfd for resample/unmask */
> + if (event_notifier_init(&vdev->intx.unmask, 0)) {
> + error_report("vfio: Error: event_notifier_init failed eoi\n");
> + goto fail;
> + }
> +
> + /* KVM triggers it, VFIO listens for it */
> + irqfd.resamplefd = event_notifier_get_fd(&vdev->intx.unmask);
> +
> + if (kvm_vm_ioctl(kvm_state, KVM_IRQFD, &irqfd)) {
> + error_report("vfio: Error: Failed to setup resample irqfd: %m\n");
> + goto fail_irqfd;
> + }
> +
> + argsz = sizeof(*irq_set) + sizeof(*pfd);
> +
> + irq_set = g_malloc0(argsz);
> + irq_set->argsz = argsz;
> + irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD | VFIO_IRQ_SET_ACTION_UNMASK;
> + irq_set->index = VFIO_PCI_INTX_IRQ_INDEX;
> + irq_set->start = 0;
> + irq_set->count = 1;
> + pfd = (int32_t *)&irq_set->data;
> +
> + *pfd = irqfd.resamplefd;
> +
> + ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, irq_set);
> + g_free(irq_set);
> + if (ret) {
> + error_report("vfio: Error: Failed to setup INTx unmask fd: %m\n");
> + goto fail_vfio;
> + }
> +
> + /* Let'em rip */
> + vfio_unmask_intx(vdev);
> +
> + vdev->intx.kvm_accel = true;
> +
> + DPRINTF("%s(%04x:%02x:%02x.%x) KVM INTx accel enabled\n",
> + __func__, vdev->host.domain, vdev->host.bus,
> + vdev->host.slot, vdev->host.function);
> +
> + return;
> +
> +fail_vfio:
> + irqfd.flags = KVM_IRQFD_FLAG_DEASSIGN;
> + kvm_vm_ioctl(kvm_state, KVM_IRQFD, &irqfd);
> +fail_irqfd:
> + event_notifier_cleanup(&vdev->intx.unmask);
> +fail:
> + qemu_set_fd_handler(irqfd.fd, vfio_intx_interrupt, NULL, vdev);
> + vfio_unmask_intx(vdev);
> +#endif
> +}
> +
> +static void vfio_disable_intx_kvm(VFIODevice *vdev)
> +{
> +#ifdef CONFIG_KVM
> + struct kvm_irqfd irqfd = {
> + .fd = event_notifier_get_fd(&vdev->intx.interrupt),
> + .gsi = vdev->intx.route.irq,
> + .flags = KVM_IRQFD_FLAG_DEASSIGN,
> + };
> +
> + if (!vdev->intx.kvm_accel) {
> + return;
> + }
> +
> + /*
> + * Get to a known state, hardware masked, QEMU ready to accept new
> + * interrupts, QEMU IRQ de-asserted.
> + */
> + vfio_mask_intx(vdev);
> + vdev->intx.pending = false;
> + qemu_set_irq(vdev->pdev.irq[vdev->intx.pin], 0);
> +
> + /* Tell KVM to stop listening for an INTx irqfd */
> + if (kvm_vm_ioctl(kvm_state, KVM_IRQFD, &irqfd)) {
> + error_report("vfio: Error: Failed to disable INTx irqfd: %m\n");
> + }
> +
> + /* We only need to close the eventfd for VFIO to cleanup the kernel side */
> + event_notifier_cleanup(&vdev->intx.unmask);
> +
> + /* QEMU starts listening for interrupt events. */
> + qemu_set_fd_handler(irqfd.fd, vfio_intx_interrupt, NULL, vdev);
> +
> + vdev->intx.kvm_accel = false;
> +
> + /* If we've missed an event, let it re-fire through QEMU */
> + vfio_unmask_intx(vdev);
> +
> + DPRINTF("%s(%04x:%02x:%02x.%x) KVM INTx accel disabled\n",
> + __func__, vdev->host.domain, vdev->host.bus,
> + vdev->host.slot, vdev->host.function);
> +#endif
> +}
> +
> +static void vfio_update_irq(PCIDevice *pdev)
> +{
> + VFIODevice *vdev = DO_UPCAST(VFIODevice, pdev, pdev);
> + PCIINTxRoute route;
> +
> + if (vdev->interrupt != VFIO_INT_INTx) {
> + return;
> + }
> +
> + route = vfio_pci_device_route_intx_to_irq(&vdev->pdev, vdev->intx.pin);
> +
> + if (!vfio_pci_intx_route_changed(&vdev->intx.route, &route)) {
> + return; /* Nothing changed */
> + }
> +
> + DPRINTF("%s(%04x:%02x:%02x.%x) IRQ moved %d -> %d\n", __func__,
> + vdev->host.domain, vdev->host.bus, vdev->host.slot,
> + vdev->host.function, vdev->intx.route.irq, route.irq);
> +
> + vfio_disable_intx_kvm(vdev);
> +
> + vdev->intx.route = route;
> +
> + if (route.mode != PCI_INTX_ENABLED) {
> + return;
> + }
> +
> + vfio_enable_intx_kvm(vdev);
> +
> + /* Re-enable the interrupt in cased we missed an EOI */
> + vfio_eoi(vdev);
> +}
> +
> static int vfio_enable_intx(VFIODevice *vdev)
> {
> uint8_t pin = vfio_pci_read_config(&vdev->pdev, PCI_INTERRUPT_PIN, 1);
> @@ -262,6 +479,9 @@ static int vfio_enable_intx(VFIODevice *vdev)
> vfio_disable_interrupts(vdev);
>
> vdev->intx.pin = pin - 1; /* Pin A (1) -> irq[0] */
> + vdev->intx.route = vfio_pci_device_route_intx_to_irq(&vdev->pdev,
> + vdev->intx.pin);
> +
> ret = event_notifier_init(&vdev->intx.interrupt, 0);
> if (ret) {
> error_report("vfio: Error: event_notifier_init failed\n");
> @@ -290,6 +510,8 @@ static int vfio_enable_intx(VFIODevice *vdev)
> return -errno;
> }
>
> + vfio_enable_intx_kvm(vdev);
> +
> vdev->interrupt = VFIO_INT_INTx;
>
> DPRINTF("%s(%04x:%02x:%02x.%x)\n", __func__, vdev->host.domain,
> @@ -303,6 +525,7 @@ static void vfio_disable_intx(VFIODevice *vdev)
> int fd;
>
> qemu_del_timer(vdev->intx.mmap_timer);
> + vfio_disable_intx_kvm(vdev);
> vfio_disable_irqindex(vdev, VFIO_PCI_INTX_IRQ_INDEX);
> vdev->intx.pending = false;
> qemu_set_irq(vdev->pdev.irq[vdev->intx.pin], 0);
> @@ -1870,6 +2093,7 @@ static int vfio_initfn(PCIDevice *pdev)
> if (vfio_pci_read_config(&vdev->pdev, PCI_INTERRUPT_PIN, 1)) {
> vdev->intx.mmap_timer = qemu_new_timer_ms(vm_clock,
> vfio_intx_mmap_enable, vdev);
> + pci_device_set_intx_routing_notifier(&vdev->pdev, vfio_update_irq);
> ret = vfio_enable_intx(vdev);
> if (ret) {
> goto out_teardown;
--
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