Re: [PATCH V3 13/22] vfio-pci: cpr part 2

[Alex Williamson <alex.williamson@redhat.com>]

On Fri,  7 May 2021 05:25:11 -0700
Steve Sistare <steven.sistare@oracle.com> wrote:

> Finish cpr for vfio-pci by preserving eventfd's and vector state.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  hw/vfio/pci.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 108 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index f7ac9f03..e983db4 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -2661,6 +2661,27 @@ static void vfio_put_device(VFIOPCIDevice *vdev)
>      vfio_put_base_device(&vdev->vbasedev);
>  }
>  
> +static void setenv_event_fd(VFIOPCIDevice *vdev, int nr, const char *name,
> +                            EventNotifier *ev)
> +{
> +    char envname[256];
> +    int fd = event_notifier_get_fd(ev);
> +    const char *vfname = vdev->vbasedev.name;
> +
> +    if (fd >= 0) {
> +        snprintf(envname, sizeof(envname), "%s_%s_%d", vfname, name, nr);
> +        setenv_fd(envname, fd);
> +    }
> +}
> +
> +static int getenv_event_fd(VFIOPCIDevice *vdev, int nr, const char *name)
> +{
> +    char envname[256];
> +    const char *vfname = vdev->vbasedev.name;
> +    snprintf(envname, sizeof(envname), "%s_%s_%d", vfname, name, nr);
> +    return getenv_fd(envname);
> +}
> +
>  static void vfio_err_notifier_handler(void *opaque)
>  {
>      VFIOPCIDevice *vdev = opaque;
> @@ -2692,7 +2713,13 @@ static void vfio_err_notifier_handler(void *opaque)
>  static void vfio_register_err_notifier(VFIOPCIDevice *vdev)
>  {
>      Error *err = NULL;
> -    int32_t fd;
> +    int32_t fd = getenv_event_fd(vdev, 0, "err");

Arg order should match the actual env names, device name, interrupt
name, interrupt number.

> +
> +    if (fd >= 0) {
> +        event_notifier_init_fd(&vdev->err_notifier, fd);
> +        qemu_set_fd_handler(fd, vfio_err_notifier_handler, NULL, vdev);
> +        return;
> +    }
>  
>      if (!vdev->pci_aer) {
>          return;
> @@ -2753,7 +2780,14 @@ static void vfio_register_req_notifier(VFIOPCIDevice *vdev)
>      struct vfio_irq_info irq_info = { .argsz = sizeof(irq_info),
>                                        .index = VFIO_PCI_REQ_IRQ_INDEX };
>      Error *err = NULL;
> -    int32_t fd;
> +    int32_t fd = getenv_event_fd(vdev, 0, "req");
> +
> +    if (fd >= 0) {
> +        event_notifier_init_fd(&vdev->req_notifier, fd);
> +        qemu_set_fd_handler(fd, vfio_req_notifier_handler, NULL, vdev);
> +        vdev->req_enabled = true;
> +        return;
> +    }
>  
>      if (!(vdev->features & VFIO_FEATURE_ENABLE_REQ)) {
>          return;
> @@ -3286,12 +3320,82 @@ static Property vfio_pci_dev_properties[] = {
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> +static int vfio_pci_pre_save(void *opaque)
> +{
> +    VFIOPCIDevice *vdev = opaque;
> +    int i;
> +
> +    for (i = 0; i < vdev->nr_vectors; i++) {
> +        VFIOMSIVector *vector = &vdev->msi_vectors[i];
> +        if (vector->use) {
> +            setenv_event_fd(vdev, i, "interrupt", &vector->interrupt);
> +            if (vector->virq >= 0) {
> +                setenv_event_fd(vdev, i, "kvm_interrupt",
> +                                &vector->kvm_interrupt);
> +            }
> +        }
> +    }
> +    setenv_event_fd(vdev, 0, "err", &vdev->err_notifier);
> +    setenv_event_fd(vdev, 0, "req", &vdev->req_notifier);
> +    return 0;
> +}
> +
> +static void vfio_claim_vectors(VFIOPCIDevice *vdev, int nr_vectors, bool msix)
> +{
> +    int i, fd;
> +    bool pending = false;
> +    PCIDevice *pdev = &vdev->pdev;
> +
> +    vdev->nr_vectors = nr_vectors;
> +    vdev->msi_vectors = g_new0(VFIOMSIVector, nr_vectors);
> +    vdev->interrupt = msix ? VFIO_INT_MSIX : VFIO_INT_MSI;
> +
> +    for (i = 0; i < nr_vectors; i++) {
> +        VFIOMSIVector *vector = &vdev->msi_vectors[i];
> +
> +        fd = getenv_event_fd(vdev, i, "interrupt");
> +        if (fd >= 0) {
> +            vfio_vector_init(vdev, i, fd);
> +            qemu_set_fd_handler(fd, vfio_msi_interrupt, NULL, vector);
> +        }
> +
> +        fd = getenv_event_fd(vdev, i, "kvm_interrupt");
> +        if (fd >= 0) {
> +            vfio_add_kvm_msi_virq(vdev, vector, i, msix, fd);
> +        }
> +
> +        if (msix && msix_is_pending(pdev, i) && msix_is_masked(pdev, i)) {
> +            set_bit(i, vdev->msix->pending);
> +            pending = true;
> +        }
> +    }
> +
> +    if (msix) {
> +        memory_region_set_enabled(&pdev->msix_pba_mmio, pending);
> +    }
> +}
> +
>  static int vfio_pci_post_load(void *opaque, int version_id)
>  {
>      VFIOPCIDevice *vdev = opaque;
>      PCIDevice *pdev = &vdev->pdev;
> +    int nr_vectors;
>      bool enabled;
>  
> +    if (msix_enabled(pdev)) {
> +        nr_vectors = vdev->msix->entries;
> +        vfio_claim_vectors(vdev, nr_vectors, true);
> +        msix_init_vector_notifiers(pdev, vfio_msix_vector_use,
> +                                   vfio_msix_vector_release, NULL);
> +
> +    } else if (msi_enabled(pdev)) {
> +        nr_vectors = msi_nr_vectors_allocated(pdev);
> +        vfio_claim_vectors(vdev, nr_vectors, false);
> +
> +    } else if (vfio_pci_read_config(pdev, PCI_INTERRUPT_PIN, 1)) {
> +        error_report("vfio_pci_post_load does not support INTX");
> +    }

Why?  Is post-load where we really want to find this out?  Thanks,

Alex

> +
>      pdev->reused = false;
>      enabled = pci_get_word(pdev->config + PCI_COMMAND) & PCI_COMMAND_MASTER;
>      memory_region_set_enabled(&pdev->bus_master_enable_region, enabled);
> @@ -3310,8 +3414,10 @@ static const VMStateDescription vfio_pci_vmstate = {
>      .version_id = 0,
>      .minimum_version_id = 0,
>      .post_load = vfio_pci_post_load,
> +    .pre_save = vfio_pci_pre_save,
>      .needed = vfio_pci_needed,
>      .fields = (VMStateField[]) {
> +        VMSTATE_MSIX(pdev, VFIOPCIDevice),
>          VMSTATE_END_OF_LIST()
>      }
>  };