linux-toradex.git/include/xen/events.h, branch v4.4.5

xen/events: Support event channel rebind on ARM

2015-08-20T11:24:15+00:00

Currently, the event channel rebind code is gated with the presence of
the vector callback.

The virtual interrupt controller on ARM has the concept of per-CPU
interrupt (PPI) which allow us to support per-VCPU event channel.
Therefore there is no need of vector callback for ARM.

Xen is already using a free PPI to notify the guest VCPU of an event.
Furthermore, the xen code initialization in Linux (see
arch/arm/xen/enlighten.c) is requesting correctly a per-CPU IRQ.

Introduce new helper xen_support_evtchn_rebind to allow architecture
decide whether rebind an event is support or not. It will always return
true on ARM and keep the same behavior on x86.

This is also allow us to drop the usage of xen_have_vector_callback
entirely in the ARM code.

Signed-off-by: Julien Grall 
Signed-off-by: David Vrabel

xen/events: don't bind non-percpu VIRQs with percpu chip

2015-05-19T18:55:36+00:00

A non-percpu VIRQ (e.g., VIRQ_CONSOLE) may be freed on a different
VCPU than it is bound to.  This can result in a race between
handle_percpu_irq() and removing the action in __free_irq() because
handle_percpu_irq() does not take desc->lock.  The interrupt handler
sees a NULL action and oopses.

Only use the percpu chip/handler for per-CPU VIRQs (like VIRQ_TIMER).

  # cat /proc/interrupts | grep virq
   40:      87246          0  xen-percpu-virq      timer0
   44:          0          0  xen-percpu-virq      debug0
   47:          0      20995  xen-percpu-virq      timer1
   51:          0          0  xen-percpu-virq      debug1
   69:          0          0   xen-dyn-virq      xen-pcpu
   74:          0          0   xen-dyn-virq      mce
   75:         29          0   xen-dyn-virq      hvc_console

Signed-off-by: David Vrabel 
Cc:

xen/events: support threaded irqs for interdomain event channels

2014-09-23T13:36:19+00:00

Export bind_interdomain_evtchn_to_irq() so drivers can use threaded
interrupt handlers with:

 irq = bind_interdomain_evtchn_to_irq(remote_dom, remote_port);
 if (irq < 0)
     /* error */
 ret = request_threaded_irq(...);

Signed-off-by: Juergen Gross 
Acked-by: Konrad Rzeszutek Wilk 
Signed-off-by: David Vrabel

xen: add support for MSI message groups

2014-03-18T14:40:09+00:00

Add support for MSI message groups for Xen Dom0 using the
MAP_PIRQ_TYPE_MULTI_MSI pirq map type.

In order to keep track of which pirq is the first one in the group all
pirqs in the MSI group except for the first one have the newly
introduced PIRQ_MSI_GROUP flag set. This prevents calling
PHYSDEVOP_unmap_pirq on them, since the unmap must be done with the
first pirq in the group.

Signed-off-by: Roger Pau Monné 
Signed-off-by: David Vrabel 
Cc: Boris Ostrovsky

xen/events: remove the unused resend_irq_on_evtchn()

2014-02-28T20:26:16+00:00

resend_irq_on_evtchn() was only used by ia64 (which no longer has Xen
support).

Signed-off-by: David Vrabel 
Signed-off-by: Konrad Rzeszutek Wilk 
Reviewed-by: Boris Ostrovsky

xen/events: allow event channel priority to be set

2014-01-06T15:07:54+00:00

Add xen_irq_set_priority() to set an event channels priority.  This function
will only work with event channel ABIs that support priority (i.e., the
FIFO-based ABI).

Signed-off-by: David Vrabel 
Reviewed-by: Konrad Rzeszutek Wilk 
Reviewed-by: Boris Ostrovsky

xen/evtchn: support more than 4096 ports

2014-01-06T15:07:50+00:00

Remove the check during unbind for NR_EVENT_CHANNELS as this limits
support to less than 4096 ports.

Signed-off-by: David Vrabel 
Reviewed-by: Konrad Rzeszutek Wilk 
Reviewed-by: Boris Ostrovsky

xen/events: move 2-level specific code into its own file

2014-01-06T15:07:41+00:00

In preparation for alternative event channel ABIs, move all the
functions accessing the shared data structures into their own file.

Signed-off-by: David Vrabel 
Reviewed-by: Konrad Rzeszutek Wilk 
Reviewed-by: Boris Ostrovsky

x86, trace: Add irq vector tracepoints

2013-06-21T05:25:34+00:00

[Purpose of this patch]

As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.

http://www.spinics.net/lists/mm-commits/msg85707.html


The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled.  They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.

There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers.  Tracing such events gives
us the information about IRQ interaction with other system events.

The trace also tells where the system is spending its time.  We want to
know which cores are handling interrupts and how they are affecting other
processes in the system.  Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.


On the other hand, my usecase is tracing just local timer event and
getting a value of instruction pointer.

I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.

[Patch Description]

Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.

So, add following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
   - local_timer_vector
   - reschedule_vector
   - call_function_vector
   - call_function_single_vector
   - irq_work_entry_vector
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
makes a zero when tracepoints are disabled. Detailed explanations are as follows.
 - Create trace irq handlers with entering_irq()/exiting_irq().
 - Create a new IDT, trace_idt_table, at boot time by adding a logic to
   _set_gate(). It is just a copy of original idt table.
 - Register the new handlers for tracpoints to the new IDT by introducing
   macros to alloc_intr_gate() called at registering time of irq_vector handlers.
 - Add checking, whether irq vector tracing is on/off, into load_current_idt().
   This has to be done below debug checking for these reasons.
   - Switching to debug IDT may be kicked while tracing is enabled.
   - On the other hands, switching to trace IDT is kicked only when debugging
     is disabled.

In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
used for other purposes.

Signed-off-by: Seiji Aguchi 
Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com
Signed-off-by: H. Peter Anvin 
Cc: Steven Rostedt

xen: drop tracking of IRQ vector

2013-04-16T19:05:45+00:00

For quite a few Xen versions, this wasn't the IRQ vector anymore
anyway, and it is not being used by the kernel for anything. Hence
drop the field from struct irq_info, and respective function
parameters.

Signed-off-by: Jan Beulich 
Acked-by: Stefano Stabellini 
Signed-off-by: Konrad Rzeszutek Wilk