/**
* This function updates the pointer to the Xen VCPU structure for each entry
* in the ARINC 653 schedule.
*
* @param ops Pointer to this instance of the scheduler structure
* @return <None>
*/
static void update_schedule_vcpus(const struct scheduler *ops)
{
unsigned int i, n_entries = SCHED_PRIV(ops)->num_schedule_entries;
for ( i = 0; i < n_entries; i++ )
SCHED_PRIV(ops)->schedule[i].vc =
find_vcpu(ops,
SCHED_PRIV(ops)->schedule[i].dom_handle,
SCHED_PRIV(ops)->schedule[i].vcpu_id);
}
/**
* This function allocates scheduler-specific data for a VCPU
*
* @param ops Pointer to this instance of the scheduler structure
*
* @return Pointer to the allocated data
*/
static void *
a653sched_alloc_vdata(const struct scheduler *ops, struct vcpu *vc, void *dd)
{
a653sched_priv_t *sched_priv = SCHED_PRIV(ops);
arinc653_vcpu_t *svc;
unsigned int entry;
unsigned long flags;
/*
* Allocate memory for the ARINC 653-specific scheduler data information
* associated with the given VCPU (vc).
*/
svc = xmalloc(arinc653_vcpu_t);
if ( svc == NULL )
return NULL;
spin_lock_irqsave(&sched_priv->lock, flags);
/*
* Add every one of dom0's vcpus to the schedule, as long as there are
* slots available.
*/
if ( vc->domain->domain_id == 0 )
{
entry = sched_priv->num_schedule_entries;
if ( entry < ARINC653_MAX_DOMAINS_PER_SCHEDULE )
{
sched_priv->schedule[entry].dom_handle[0] = '\0';
sched_priv->schedule[entry].vcpu_id = vc->vcpu_id;
sched_priv->schedule[entry].runtime = DEFAULT_TIMESLICE;
sched_priv->schedule[entry].vc = vc;
sched_priv->major_frame += DEFAULT_TIMESLICE;
++sched_priv->num_schedule_entries;
}
}
/*
* Initialize our ARINC 653 scheduler-specific information for the VCPU.
* The VCPU starts "asleep." When Xen is ready for the VCPU to run, it
* will call the vcpu_wake scheduler callback function and our scheduler
* will mark the VCPU awake.
*/
svc->vc = vc;
svc->awake = 0;
if ( !is_idle_vcpu(vc) )
list_add(&svc->list, &SCHED_PRIV(ops)->vcpu_list);
update_schedule_vcpus(ops);
spin_unlock_irqrestore(&sched_priv->lock, flags);
return svc;
}
/**
* This function is called by the adjust_global scheduler hook to read the
* current ARINC 653 schedule
*
* @param ops Pointer to this instance of the scheduler structure
* @return <ul>
* <li> 0 = success
* <li> !0 = error
* </ul>
*/
static int
arinc653_sched_get(
const struct scheduler *ops,
struct xen_sysctl_arinc653_schedule *schedule)
{
a653sched_priv_t *sched_priv = SCHED_PRIV(ops);
unsigned int i;
unsigned long flags;
spin_lock_irqsave(&sched_priv->lock, flags);
schedule->num_sched_entries = sched_priv->num_schedule_entries;
schedule->major_frame = sched_priv->major_frame;
for ( i = 0; i < sched_priv->num_schedule_entries; i++ )
{
memcpy(schedule->sched_entries[i].dom_handle,
sched_priv->schedule[i].dom_handle,
sizeof(sched_priv->schedule[i].dom_handle));
schedule->sched_entries[i].vcpu_id = sched_priv->schedule[i].vcpu_id;
schedule->sched_entries[i].runtime = sched_priv->schedule[i].runtime;
}
spin_unlock_irqrestore(&sched_priv->lock, flags);
return 0;
}
/**
* This function searches the vcpu list to find a VCPU that matches
* the domain handle and VCPU ID specified.
*
* @param ops Pointer to this instance of the scheduler structure
* @param handle Pointer to handler
* @param vcpu_id VCPU ID
*
* @return <ul>
* <li> Pointer to the matching VCPU if one is found
* <li> NULL otherwise
* </ul>
*/
static struct vcpu *find_vcpu(
const struct scheduler *ops,
xen_domain_handle_t handle,
int vcpu_id)
{
arinc653_vcpu_t *avcpu;
/* loop through the vcpu_list looking for the specified VCPU */
list_for_each_entry ( avcpu, &SCHED_PRIV(ops)->vcpu_list, list )
if ( (dom_handle_cmp(avcpu->vc->domain->handle, handle) == 0)
&& (vcpu_id == avcpu->vc->vcpu_id) )
return avcpu->vc;
return NULL;
}
/**
* Xen scheduler callback function to select a VCPU to run.
* This is the main scheduler routine.
*
* @param ops Pointer to this instance of the scheduler structure
* @param now Current time
*
* @return Address of the VCPU structure scheduled to be run next
* Amount of time to execute the returned VCPU
* Flag for whether the VCPU was migrated
*/
static struct task_slice
a653sched_do_schedule(
const struct scheduler *ops,
s_time_t now,
bool_t tasklet_work_scheduled)
{
struct task_slice ret; /* hold the chosen domain */
struct vcpu * new_task = NULL;
static unsigned int sched_index = 0;
static s_time_t next_switch_time;
a653sched_priv_t *sched_priv = SCHED_PRIV(ops);
const unsigned int cpu = smp_processor_id();
unsigned long flags;
spin_lock_irqsave(&sched_priv->lock, flags);
if ( sched_priv->num_schedule_entries < 1 )
sched_priv->next_major_frame = now + DEFAULT_TIMESLICE;
else if ( now >= sched_priv->next_major_frame )
{
/* time to enter a new major frame
* the first time this function is called, this will be true */
/* start with the first domain in the schedule */
sched_index = 0;
sched_priv->next_major_frame = now + sched_priv->major_frame;
next_switch_time = now + sched_priv->schedule[0].runtime;
}
else
{
while ( (now >= next_switch_time)
&& (sched_index < sched_priv->num_schedule_entries) )
{
/* time to switch to the next domain in this major frame */
sched_index++;
next_switch_time += sched_priv->schedule[sched_index].runtime;
}
}
/*
* If we exhausted the domains in the schedule and still have time left
* in the major frame then switch next at the next major frame.
*/
if ( sched_index >= sched_priv->num_schedule_entries )
next_switch_time = sched_priv->next_major_frame;
/*
* If there are more domains to run in the current major frame, set
* new_task equal to the address of next domain's VCPU structure.
* Otherwise, set new_task equal to the address of the idle task's VCPU
* structure.
*/
new_task = (sched_index < sched_priv->num_schedule_entries)
? sched_priv->schedule[sched_index].vc
: IDLETASK(cpu);
/* Check to see if the new task can be run (awake & runnable). */
if ( !((new_task != NULL)
&& (AVCPU(new_task) != NULL)
&& AVCPU(new_task)->awake
&& vcpu_runnable(new_task)) )
new_task = IDLETASK(cpu);
BUG_ON(new_task == NULL);
/*
* Check to make sure we did not miss a major frame.
* This is a good test for robust partitioning.
*/
BUG_ON(now >= sched_priv->next_major_frame);
spin_unlock_irqrestore(&sched_priv->lock, flags);
/* Tasklet work (which runs in idle VCPU context) overrides all else. */
if ( tasklet_work_scheduled )
new_task = IDLETASK(cpu);
/* Running this task would result in a migration */
if ( !is_idle_vcpu(new_task)
&& (new_task->processor != cpu) )
new_task = IDLETASK(cpu);
/*
* Return the amount of time the next domain has to run and the address
* of the selected task's VCPU structure.
*/
ret.time = next_switch_time - now;
ret.task = new_task;
ret.migrated = 0;
BUG_ON(ret.time <= 0);
return ret;
}
/**
* This function allocates scheduler-specific data for a domain
*
* We do not actually make use of any per-domain data but the hypervisor
* expects a non-NULL return value
*
* @param ops Pointer to this instance of the scheduler structure
*
* @return Pointer to the allocated data
*/
static void *
a653sched_alloc_domdata(const struct scheduler *ops, struct domain *dom)
{
/* return a non-NULL value to keep schedule.c happy */
return SCHED_PRIV(ops);
}
/**
* This function allocates scheduler-specific data for a physical CPU
*
* We do not actually make use of any per-CPU data but the hypervisor expects
* a non-NULL return value
*
* @param ops Pointer to this instance of the scheduler structure
*
* @return Pointer to the allocated data
*/
static void *
a653sched_alloc_pdata(const struct scheduler *ops, int cpu)
{
/* return a non-NULL value to keep schedule.c happy */
return SCHED_PRIV(ops);
}
/**
* This function performs deinitialization for an instance of the scheduler
*
* @param ops Pointer to this instance of the scheduler structure
*/
static void
a653sched_deinit(const struct scheduler *ops)
{
xfree(SCHED_PRIV(ops));
}
/**
* This function is called by the adjust_global scheduler hook to put
* in place a new ARINC653 schedule.
*
* @param ops Pointer to this instance of the scheduler structure
*
* @return <ul>
* <li> 0 = success
* <li> !0 = error
* </ul>
*/
static int
arinc653_sched_set(
const struct scheduler *ops,
struct xen_sysctl_arinc653_schedule *schedule)
{
a653sched_priv_t *sched_priv = SCHED_PRIV(ops);
s_time_t total_runtime = 0;
unsigned int i;
unsigned long flags;
int rc = -EINVAL;
spin_lock_irqsave(&sched_priv->lock, flags);
/* Check for valid major frame and number of schedule entries. */
if ( (schedule->major_frame <= 0)
|| (schedule->num_sched_entries < 1)
|| (schedule->num_sched_entries > ARINC653_MAX_DOMAINS_PER_SCHEDULE) )
goto fail;
for ( i = 0; i < schedule->num_sched_entries; i++ )
{
/* Check for a valid run time. */
if ( schedule->sched_entries[i].runtime <= 0 )
goto fail;
/* Add this entry's run time to total run time. */
total_runtime += schedule->sched_entries[i].runtime;
}
/*
* Error if the major frame is not large enough to run all entries as
* indicated by comparing the total run time to the major frame length.
*/
if ( total_runtime > schedule->major_frame )
goto fail;
/* Copy the new schedule into place. */
sched_priv->num_schedule_entries = schedule->num_sched_entries;
sched_priv->major_frame = schedule->major_frame;
for ( i = 0; i < schedule->num_sched_entries; i++ )
{
memcpy(sched_priv->schedule[i].dom_handle,
schedule->sched_entries[i].dom_handle,
sizeof(sched_priv->schedule[i].dom_handle));
sched_priv->schedule[i].vcpu_id =
schedule->sched_entries[i].vcpu_id;
sched_priv->schedule[i].runtime =
schedule->sched_entries[i].runtime;
}
update_schedule_vcpus(ops);
/*
* The newly-installed schedule takes effect immediately. We do not even
* wait for the current major frame to expire.
*
* Signal a new major frame to begin. The next major frame is set up by
* the do_schedule callback function when it is next invoked.
*/
sched_priv->next_major_frame = NOW();
rc = 0;
fail:
spin_unlock_irqrestore(&sched_priv->lock, flags);
return rc;
}
/**
* This function performs deinitialization for an instance of the scheduler
*
* @param ops Pointer to this instance of the scheduler structure
*/
static void
a653sched_deinit(struct scheduler *ops)
{
xfree(SCHED_PRIV(ops));
ops->sched_data = NULL;
}
