Re: [Qemu-devel] [PATCH v1 2/2] hw/pvrdma: add live migration support

[Yuval Shaia <yuval.shaia@oracle.com>]

On Wed, Aug 28, 2019 at 07:53:28PM +0530, Sukrit Bhatnagar wrote:
> vmstate_pvrdma describes the PCI and MSIX states as well as the dma
> address for dsr and the gid table of device.
> vmstate_pvrdma_gids describes each gid in the gid table.
> 
> pvrdma_post_save() does the job of unregistering gid entries from the
> backend device in the source host.
> 
> pvrdma_post_load() maps to dsr using the loaded dma address, registers
> each loaded gid into the backend device, and finally calls load_dsr()
> to perform other mappings and ring init operations.

I think it worth to mention that the dma address is kept in driver/device
shared memory (dsr->dma) which is migrated as part of memory migration and
it is out of the scope of this change and so we do not need to save/load
the dma address during migration.

Also you should specifically comment that this migration-support does not
includes QP migration. This means that support for life migration *during*
traffic is not yet supported.

> 
> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> Cc: Yuval Shaia <yuval.shaia@oracle.com>
> Signed-off-by: Sukrit Bhatnagar <skrtbhtngr@gmail.com>
> ---
>  hw/rdma/vmw/pvrdma_main.c | 77 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 77 insertions(+)
> 
> diff --git a/hw/rdma/vmw/pvrdma_main.c b/hw/rdma/vmw/pvrdma_main.c
> index 6c90db96f9..6f8b56dea3 100644
> --- a/hw/rdma/vmw/pvrdma_main.c
> +++ b/hw/rdma/vmw/pvrdma_main.c
> @@ -28,6 +28,7 @@
>  #include "sysemu/sysemu.h"
>  #include "monitor/monitor.h"
>  #include "hw/rdma/rdma.h"
> +#include "migration/register.h"
>  
>  #include "../rdma_rm.h"
>  #include "../rdma_backend.h"
> @@ -593,6 +594,81 @@ static void pvrdma_shutdown_notifier(Notifier *n, void *opaque)
>      pvrdma_fini(pci_dev);
>  }
>  
> +static int pvrdma_post_save(void *opaque)
> +{
> +    int i, rc;
> +    PVRDMADev *dev = opaque;
> +
> +    for (i = 0; i < MAX_GIDS; i++) {
> +

Empty line is redundant here.

> +        if (!dev->rdma_dev_res.port.gid_tbl[i].gid.global.interface_id) {
> +            continue;
> +        }
> +        rc = rdma_backend_del_gid(&dev->backend_dev,
> +                                   dev->backend_eth_device_name,
> +                                   &dev->rdma_dev_res.port.gid_tbl[i].gid);
> +        if (rc) {
> +            return -EINVAL;

Some error report will help here i guess.

> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +static int pvrdma_post_load(void *opaque, int version_id)
> +{
> +    int i, rc;
> +    PVRDMADev *dev = opaque;
> +    PCIDevice *pci_dev = PCI_DEVICE(dev);
> +    DSRInfo *dsr_info = &dev->dsr_info;
> +
> +    dsr_info->dsr = rdma_pci_dma_map(pci_dev, dsr_info->dma,
> +                                sizeof(struct pvrdma_device_shared_region));
> +    if (!dsr_info->dsr) {
> +        rdma_error_report("Failed to map to DSR");
> +        return -ENOMEM;
> +    }
> +
> +    for (i = 0; i < MAX_GIDS; i++) {
> +

Empty line is redundant here.

> +        if (!dev->rdma_dev_res.port.gid_tbl[i].gid.global.interface_id) {
> +            continue;
> +        }
> +
> +        rc = rdma_backend_add_gid(&dev->backend_dev,
> +                                  dev->backend_eth_device_name,
> +                                  &dev->rdma_dev_res.port.gid_tbl[i].gid);
> +        if (rc) {
> +            return -EINVAL;
> +        }
> +    }
> +
> +    return load_dsr(dev);
> +}
> +
> +static const VMStateDescription vmstate_pvrdma_gids = {
> +    .name = "pvrdma-gids",
> +    .fields = (VMStateField[]) {
> +            VMSTATE_UINT8_ARRAY_V(gid.raw, RdmaRmGid, 16, 0),
> +            VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static const VMStateDescription vmstate_pvrdma = {
> +    .name = PVRDMA_HW_NAME,
> +    .post_save = pvrdma_post_save,
> +    .post_load = pvrdma_post_load,
> +    .fields = (VMStateField[]) {
> +            VMSTATE_PCI_DEVICE(parent_obj, PVRDMADev),
> +            VMSTATE_MSIX(parent_obj, PVRDMADev),
> +            VMSTATE_UINT64(dsr_info.dma, PVRDMADev),
> +            VMSTATE_STRUCT_ARRAY(rdma_dev_res.port.gid_tbl, PVRDMADev,
> +                                 MAX_PORT_GIDS, 0, vmstate_pvrdma_gids,
> +                                 RdmaRmGid),
> +            VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static void pvrdma_realize(PCIDevice *pdev, Error **errp)
>  {
>      int rc = 0;
> @@ -688,6 +764,7 @@ static void pvrdma_class_init(ObjectClass *klass, void *data)
>  
>      dc->desc = "RDMA Device";
>      dc->props = pvrdma_dev_properties;
> +    dc->vmsd = &vmstate_pvrdma;
>      set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
>  
>      ir->print_statistics = pvrdma_print_statistics;
> -- 
> 2.21.0
> 
>