On Wed, 2016-03-16 at 11:47 -0500, Chong Li wrote:
> --- a/xen/common/sched_credit.c
> +++ b/xen/common/sched_credit.c
> @@ -1054,15 +1054,16 @@ csched_dom_cntl(
>       * lock. Runq lock not needed anywhere in here. */
>      spin_lock_irqsave(&prv->lock, flags);
>  
> -    if ( op->cmd == XEN_DOMCTL_SCHEDOP_getinfo )
> +    switch ( op->cmd )
>      {
> +    case XEN_DOMCTL_SCHEDOP_putvcpuinfo:
> +    case XEN_DOMCTL_SCHEDOP_getvcpuinfo:
> +        return -EINVAL;
> +    case XEN_DOMCTL_SCHEDOP_getinfo:
>          op->u.credit.weight = sdom->weight;
>          op->u.credit.cap = sdom->cap;
>
Not feeling to strong about it, but I think

    switch ( op->cmd )
    {
    case XEN_DOMCTL_SCHEDOP_getinfo:
        op->u.credit.weight = sdom->weight;
        op->u.credit.cap = sdom->cap;
        break;
    case XEN_DOMCTL_SCHEDOP_putinfo:
        if ( op->u.credit.weight != 0 )
        {
            if ( !list_empty(&sdom->active_sdom_elem) )
            {
                prv->weight -= sdom->weight * sdom->active_vcpu_count;
                prv->weight += op->u.credit.weight * sdom->active_vcpu_count;
            }
            sdom->weight = op->u.credit.weight;
        }

        if ( op->u.credit.cap != (uint16_t)~0U )
            sdom->cap = op->u.credit.cap;
        break;
    case XEN_DOMCTL_SCHEDOP_putvcpuinfo:
    case XEN_DOMCTL_SCHEDOP_getvcpuinfo:
    default:
        return -EINVAL;
    }

(i.e., grouping the cases that needs only returning -EINVAL) is better,
the final result, more than the patch itself.

And the same for Credit2, of course.

> --- a/xen/common/sched_rt.c
> +++ b/xen/common/sched_rt.c
> @@ -1129,24 +1145,22 @@ rt_dom_cntl(
>      struct vcpu *v;
>      unsigned long flags;
>      int rc = 0;
> +    xen_domctl_schedparam_vcpu_t local_sched;
> +    s_time_t period, budget;
> +    uint32_t index = 0;
>  
>      switch ( op->cmd )
>      {
>      case XEN_DOMCTL_SCHEDOP_getinfo:
> -        if ( d->max_vcpus > 0 )
> -        {
> -            spin_lock_irqsave(&prv->lock, flags);
> -            svc = rt_vcpu(d->vcpu[0]);
> -            op->u.rtds.period = svc->period / MICROSECS(1);
> -            op->u.rtds.budget = svc->budget / MICROSECS(1);
> -            spin_unlock_irqrestore(&prv->lock, flags);
> -        }
> -        else
> -        {
> -            /* If we don't have vcpus yet, let's just return the
> defaults. */
> -            op->u.rtds.period = RTDS_DEFAULT_PERIOD;
> -            op->u.rtds.budget = RTDS_DEFAULT_BUDGET;
> -        }
> +        /* Return the default parameters.
> +         * A previous bug fixed here:
> +         * The default PERIOD or BUDGET should be divided by
> MICROSECS(1),
> +         * before returned to upper caller.
> +         */
Comment style (missing opening '/*').

Also, putting this kind of things in comments is not at all ideal. If
doing this in this patch, you should mention it in the changelog. Or
you do it in a separate patch (that you put before this one in the
series).

I'd say that, in this specific case, is not a big deal which one of the
two approaches you take (mentioning or separate patch), but the having
a separate one is indeed almost always preferable (e.g., the fix can be
backported).

> +        spin_lock_irqsave(&prv->lock, flags);
> +        op->u.rtds.period = RTDS_DEFAULT_PERIOD / MICROSECS(1);
> +        op->u.rtds.budget = RTDS_DEFAULT_BUDGET / MICROSECS(1);
> +        spin_unlock_irqrestore(&prv->lock, flags);
>
I don't think we need to take the lock here... RTDS_DEFAULT_PERIOD is
not going to change under our feet. :-)

> @@ -1163,6 +1177,78 @@ rt_dom_cntl(
>          }
>          spin_unlock_irqrestore(&prv->lock, flags);
>          break;
> +    case XEN_DOMCTL_SCHEDOP_getvcpuinfo:
> +        while ( index < op->u.v.nr_vcpus )
> +        {
> +            if ( copy_from_guest_offset(&local_sched,
> +                                        op->u.v.vcpus, index, 1) )
> +            {
> +                rc = -EFAULT;
> +                break;
> +            }
> +            if ( local_sched.vcpuid >= d->max_vcpus ||
> +                 d->vcpu[local_sched.vcpuid] == NULL )
> +            {
> +                rc = -EINVAL;
> +                break;
> +            }
> +
> +            spin_lock_irqsave(&prv->lock, flags);
> +            svc = rt_vcpu(d->vcpu[local_sched.vcpuid]);
> +            local_sched.u.rtds.budget = svc->budget / MICROSECS(1);
> +            local_sched.u.rtds.period = svc->period / MICROSECS(1);
> +            spin_unlock_irqrestore(&prv->lock, flags);
> +
> +            if ( copy_to_guest_offset(op->u.v.vcpus, index,
> +                                        &local_sched, 1) )
> +            {
> +                rc = -EFAULT;
> +                break;
> +            }
> +            if ( (++index > 0x3f) && hypercall_preempt_check() )
> +                break;
>
So, I know it's 0x3f in XEN_SYSCTL_pcitopoinfo, but unless I'm missing
something, I don't see why this can't be "63".

I'd also put a short comment right above, something like:

 /* Process a most 64 vCPUs without checking for preemptions. */

> +        }
> +        if ( !rc ) /* notify upper caller how many vcpus have been
> processed */
>
Move the comment to the line above (and terminate it with a full stop).

And by the way, there's a lot of code repetition here. What about
handling get and set together, sort of like this:

    case XEN_DOMCTL_SCHEDOP_getvcpuinfo:                                                                              |
    case XEN_DOMCTL_SCHEDOP_putvcpuinfo:                                                                              |#ifdef CONFIG_HAS_PCI
        while ( index < op->u.v.nr_vcpus )                                                                            |    case XEN_SYSCTL_pcitopoinfo:
        {                                                                                                             |    {
            if ( copy_from_guest_offset(&local_sched,                                                                 |        xen_sysctl_pcitopoinfo_t *ti = &op->u.pcitopoinfo;
                                        op->u.v.vcpus, index, 1) )                                                    |        unsigned int i = 0;
            {                                                                                                         |
                rc = -EFAULT;                                                                                         |        if ( guest_handle_is_null(ti->devs) ||
                break;                                                                                                |             guest_handle_is_null(ti->nodes) )
            }                                                                                                         |        {
                                                                                                                      |            ret = -EINVAL;
            if ( local_sched.vcpuid >= d->max_vcpus ||                                                                |            break;
                 d->vcpu[local_sched.vcpuid] == NULL )                                                                |        }
            {                                                                                                         |
                rc = -EINVAL;                                                                                         |        while ( i < ti->num_devs )
                break;                                                                                                |        {
            }                                                                                                         |            physdev_pci_device_t dev;
                                                                                                                      |            uint32_t node;
            if ( op->cmd == XEN_DOMCTL_SCHEDOP_getvcpuinfo )                                                          |            const struct pci_dev *pdev;
            {                                                                                                         |
                spin_lock_irqsave(&prv->lock, flags);                                                                 |            if ( copy_from_guest_offset(&dev, ti->devs, i, 1) )
                svc = rt_vcpu(d->vcpu[local_sched.vcpuid]);                                                           |            {
                local_sched.u.rtds.budget = svc->budget / MICROSECS(1);                                               |                ret = -EFAULT;
                local_sched.u.rtds.period = svc->period / MICROSECS(1);                                               |                break;
                spin_unlock_irqrestore(&prv->lock, flags);                                                            |            }
                                                                                                                      |
                if ( copy_to_guest_offset(op->u.v.vcpus, index,                                                       |            pcidevs_lock();
                                          &local_sched, 1) )                                                          |            pdev = pci_get_pdev(dev.seg, dev.bus, dev.devfn);
                {                                                                                                     |            if ( !pdev )
                    rc = -EFAULT;                                                                                     |                node = XEN_INVALID_DEV;
                    break;                                                                                            |            else if ( pdev->node == NUMA_NO_NODE )
                }                                                                                                     |                node = XEN_INVALID_NODE_ID;
            }                                                                                                         |            else
            else                                                                                                      |                node = pdev->node;
            {                                                                                                         |            pcidevs_unlock();
                period = MICROSECS(local_sched.u.rtds.period);                                                        |
                budget = MICROSECS(local_sched.u.rtds.budget);                                                        |            if ( copy_to_guest_offset(ti->nodes, i, &node, 1) )
                if ( period > RTDS_MAX_PERIOD || budget < RTDS_MIN_BUDGET ||                                          |            {
                     budget > period || period < RTDS_MIN_PERIOD )                                                    |                ret = -EFAULT;
                {                                                                                                     |                break;
                    rc = -EINVAL;                                                                                     |            }
                    break;                                                                                            |
                }                                                                                                     |            /* Process a most 64 vCPUs without checking for preemptions. */
                                                                                                                      |            if ( (++i > 0x3f) && hypercall_preempt_check() )
                spin_lock_irqsave(&prv->lock, flags);                                                                 |                break;
                svc = rt_vcpu(d->vcpu[local_sched.vcpuid]);                                                           |        }
                svc->period = period;                                                                                 |
                svc->budget = budget;                                                                                 |        if ( !ret && (ti->num_devs != i) )
                spin_unlock_irqrestore(&prv->lock, flags);                                                            |        {
                                                                                                                      |            ti->num_devs = i;
            }                                                                                                         |            if ( __copy_field_to_guest(u_sysctl, op, u.pcitopoinfo.num_devs) )
            /* Process a most 64 vCPUs without checking for preemptions. */                                           |                ret = -EFAULT;
            if ( (++index > 63) && hypercall_preempt_check() )                                                        |        }
                break;                                                                                                |        break;
        }                                                                                                             |    }
                                                                                                                      |#endif
        /* Notify upper caller how many vcpus have been processed. */                                                 |
        if ( !rc )                                                                                                    |    case XEN_SYSCTL_tmem_op:
            op->u.v.nr_vcpus = index;                                                                                 |        ret = tmem_control(&op->u.tmem_op);
        break;

I have only compile tested this, but it looks to me that it can fly...

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h

> + * Set or get info?
> + * For schedulers supporting per-vcpu settings (e.g., RTDS):
> + *  XEN_DOMCTL_SCHEDOP_putinfo sets params for all vcpus;
> + *  XEN_DOMCTL_SCHEDOP_getinfo gets default params;
> + *  XEN_DOMCTL_SCHEDOP_put(get)vcpuinfo sets (gets) params of vcpus;
> + *
> + * For schedulers not supporting per-vcpu settings:
> + *  XEN_DOMCTL_SCHEDOP_putinfo sets params for all vcpus;
> + *  XEN_DOMCTL_SCHEDOP_getinfo gets domain-wise params;
> + *  XEN_DOMCTL_SCHEDOP_put(get)vcpuinfo returns error;
> + */
>  #define XEN_DOMCTL_SCHEDOP_putinfo 0
>  #define XEN_DOMCTL_SCHEDOP_getinfo 1
> +#define XEN_DOMCTL_SCHEDOP_putvcpuinfo 2
> +#define XEN_DOMCTL_SCHEDOP_getvcpuinfo 3
>  struct xen_domctl_scheduler_op {
>      uint32_t sched_id;  /* XEN_SCHEDULER_* */
>      uint32_t cmd;       /* XEN_DOMCTL_SCHEDOP_* */

       /* IN/OUT */
>      union {
> -        struct xen_domctl_sched_credit {
> -            uint16_t weight;
> -            uint16_t cap;
> -        } credit;
> -        struct xen_domctl_sched_credit2 {
> -            uint16_t weight;
> -        } credit2;
> -        struct xen_domctl_sched_rtds {
> -            uint32_t period;
> -            uint32_t budget;
> -        } rtds;
> +        xen_domctl_sched_credit_t credit;
> +        xen_domctl_sched_credit2_t credit2;
> +        xen_domctl_sched_rtds_t rtds;
> +        struct {
> +            XEN_GUEST_HANDLE_64(xen_domctl_schedparam_vcpu_t) vcpus;
> +            /*
> +             * IN: Number of elements in vcpus array.
> +             * OUT: Number of processed elements of vcpus array.
> +             */
> +            uint32_t nr_vcpus;
> +            uint32_t padding;
> +        } v;
>      } u;
>  };
>
That is: make it even more clear that the whole union is used as
IN/OUT.

Then, indeed, inside v, what is the meaning of the nr_vcpus field in
each direction, as you're doing already.

Regards,
Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)