Re: [Qemu-devel] [PATCH 1/2] ipmi: Use proper struct reference for KCS vmstate

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* minyard@acm.org (minyard@acm.org) wrote:
> From: Corey Minyard <cminyard@mvista.com>

Hi Corey,

> The vmstate for isa_ipmi_kcs was referencing into the kcs structure,
> instead create a kcs structure separate and use that.
> 
> There was also some issues in the state transfer.  The inlen field
> was not being transferred, so if a transaction was in process during
> the transfer it would be messed up.  And the use_irq field was
> transferred, but that should come from the configuration.  This
> also fixes those issues and is tested under heavy load.
> 
> Signed-off-by: Corey Minyard <cminyard@mvista.com>
> ---
>  hw/ipmi/isa_ipmi_kcs.c | 75 ++++++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 60 insertions(+), 15 deletions(-)
> 
> diff --git a/hw/ipmi/isa_ipmi_kcs.c b/hw/ipmi/isa_ipmi_kcs.c
> index 689587b..3c942d6 100644
> --- a/hw/ipmi/isa_ipmi_kcs.c
> +++ b/hw/ipmi/isa_ipmi_kcs.c
> @@ -422,24 +422,69 @@ static void ipmi_isa_realize(DeviceState *dev, Error **errp)
>      isa_register_ioport(isadev, &iik->kcs.io, iik->kcs.io_base);
>  }
>  
> -const VMStateDescription vmstate_ISAIPMIKCSDevice = {
> -    .name = TYPE_IPMI_INTERFACE,
> +static const VMStateDescription vmstate_IPMIKCS = {
> +    .name = TYPE_IPMI_INTERFACE_PREFIX "kcs",
>      .version_id = 1,
>      .minimum_version_id = 1,
>      .fields      = (VMStateField[]) {
> -        VMSTATE_BOOL(kcs.obf_irq_set, ISAIPMIKCSDevice),
> -        VMSTATE_BOOL(kcs.atn_irq_set, ISAIPMIKCSDevice),
> -        VMSTATE_BOOL(kcs.use_irq, ISAIPMIKCSDevice),
> -        VMSTATE_BOOL(kcs.irqs_enabled, ISAIPMIKCSDevice),
> -        VMSTATE_UINT32(kcs.outpos, ISAIPMIKCSDevice),
> -        VMSTATE_UINT8_ARRAY(kcs.outmsg, ISAIPMIKCSDevice, MAX_IPMI_MSG_SIZE),
> -        VMSTATE_UINT8_ARRAY(kcs.inmsg, ISAIPMIKCSDevice, MAX_IPMI_MSG_SIZE),
> -        VMSTATE_BOOL(kcs.write_end, ISAIPMIKCSDevice),
> -        VMSTATE_UINT8(kcs.status_reg, ISAIPMIKCSDevice),
> -        VMSTATE_UINT8(kcs.data_out_reg, ISAIPMIKCSDevice),
> -        VMSTATE_INT16(kcs.data_in_reg, ISAIPMIKCSDevice),
> -        VMSTATE_INT16(kcs.cmd_reg, ISAIPMIKCSDevice),
> -        VMSTATE_UINT8(kcs.waiting_rsp, ISAIPMIKCSDevice),
> +        VMSTATE_BOOL(obf_irq_set, IPMIKCS),
> +        VMSTATE_BOOL(atn_irq_set, IPMIKCS),
> +        VMSTATE_BOOL(use_irq, IPMIKCS),
> +        VMSTATE_BOOL(irqs_enabled, IPMIKCS),
> +        VMSTATE_UINT32(outpos, IPMIKCS),
> +        VMSTATE_UINT8_ARRAY(outmsg, IPMIKCS, MAX_IPMI_MSG_SIZE),
> +        VMSTATE_UINT32(inlen, IPMIKCS),
> +        VMSTATE_UINT8_ARRAY(inmsg, IPMIKCS, MAX_IPMI_MSG_SIZE),

There's an easier way to do this, which means that you don't need the
load_old hook; you can do:

  VMSTATE_UINT32_V(inlen, IPMIKCS, 2);

and that field will only be loaded when loading a v2.


Now, the other thing you could do, if it's rare then inlen is none-0,
is you could add it as a subsection that only gets sent when it's
none-0; that way migration to an old qemu would work in most cases.

Dave

> +        VMSTATE_BOOL(write_end, IPMIKCS),
> +        VMSTATE_UINT8(status_reg, IPMIKCS),
> +        VMSTATE_UINT8(data_out_reg, IPMIKCS),
> +        VMSTATE_INT16(data_in_reg, IPMIKCS),
> +        VMSTATE_INT16(cmd_reg, IPMIKCS),
> +        VMSTATE_UINT8(waiting_rsp, IPMIKCS),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static int isa_ipmi_kcs_load_old(QEMUFile *f, void *opaque, int version_id)
> +{
> +    ISAIPMIKCSDevice *iik = opaque;
> +    IPMIKCS *k = &iik->kcs;
> +    unsigned int i;
> +
> +    if (version_id != 1) {
> +        return -EINVAL;
> +    }
> +
> +    k->obf_irq_set = qemu_get_byte(f);
> +    k->atn_irq_set = qemu_get_byte(f);
> +    qemu_get_byte(f); /* Used to be use_irq, but that's not a good idea. */
> +    k->irqs_enabled = qemu_get_byte(f);
> +    k->outpos = qemu_get_be32(f);
> +    for (i = 0; i < MAX_IPMI_MSG_SIZE; i++) {
> +        k->outmsg[i] = qemu_get_byte(f);
> +    }
> +    k->inlen = 0; /* This was forgotten on version 1, just reset it. */
> +    for (i = 0; i < MAX_IPMI_MSG_SIZE; i++) {
> +        k->inmsg[i] = qemu_get_byte(f);
> +    }
> +    k->write_end = qemu_get_byte(f);
> +    k->status_reg = qemu_get_byte(f);
> +    k->data_out_reg = qemu_get_byte(f);
> +    k->data_in_reg = qemu_get_be16(f);
> +    k->cmd_reg = qemu_get_be16(f);
> +    k->waiting_rsp = qemu_get_byte(f);
> +
> +    return 0;
> +}
> +
> +static const VMStateDescription vmstate_ISAIPMIKCSDevice = {
> +    .name = TYPE_IPMI_INTERFACE_PREFIX "isa-kcs",
> +    .version_id = 2,
> +    .minimum_version_id = 2,
> +    .minimum_version_id_old = 1,
> +    .load_state_old = isa_ipmi_kcs_load_old,
> +    .fields      = (VMStateField[]) {
> +        VMSTATE_STRUCT(kcs, ISAIPMIKCSDevice, 1, vmstate_IPMIKCS, IPMIKCS),
>          VMSTATE_END_OF_LIST()
>      }
>  };
> -- 
> 2.7.4
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK