kernel.git/include/xen/events.h, branch linux-3.13.y

x86, trace: Add irq vector tracepoints

2013-06-21T05:25:34Z

[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

2013-04-16T19:05:45Z

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

xen/arm: receive Xen events on ARM

2012-09-14T13:37:32Z

Compile events.c on ARM. Parse, map and enable the IRQ to get event notifications from the device tree (node "/xen"). Signed-off-by: Stefano Stabellini Acked-by: Konrad Rzeszutek Wilk

xen: do not map the same GSI twice in PVHVM guests.

2012-05-21T18:11:36Z

PV on HVM guests map GSIs into event channels. At restore time the event channels are resumed by restore_pirqs. Device drivers might try to register the same GSI again through ACPI at restore time, but the GSI has already been mapped and bound by restore_pirqs. This patch detects these situations and avoids mapping the same GSI multiple times. Without this patch we get: (XEN) irq.c:2235: dom4: pirq 23 or emuirq 28 already mapped and waste a pirq. CC: stable@kernel.org Signed-off-by: Stefano Stabellini Signed-off-by: Konrad Rzeszutek Wilk

xen/event: Add reference counting to event channels

2011-11-21T22:14:48Z

Event channels exposed to userspace by the evtchn module may be used by other modules in an asynchronous manner, which requires that reference counting be used to prevent the event channel from being closed before the signals are delivered. The reference count on new event channels defaults to -1 which indicates the event channel is not referenced outside the kernel; evtchn_get fails if called on such an event channel. The event channels made visible to userspace by evtchn have a normal reference count. Signed-off-by: Daniel De Graaf Signed-off-by: Konrad Rzeszutek Wilk

xen/pci: Remove 'xen_allocate_pirq_gsi'.

2011-07-11T17:19:33Z

In the past (2.6.38) the 'xen_allocate_pirq_gsi' would allocate an entry in a Linux IRQ -> {XEN_IRQ, type, event, ..} array. All of that has been removed in 2.6.39 and the Xen IRQ subsystem uses an linked list that is populated when the call to 'xen_allocate_irq_gsi' (universally done from any of the xen_bind_* calls) is done. The 'xen_allocate_pirq_gsi' is a NOP and there is no need for it anymore so lets remove it. Signed-off-by: Konrad Rzeszutek Wilk

xen/irq: Export 'xen_pirq_from_irq' function.

2011-04-14T15:17:55Z

We need this to find the real Xen PIRQ value for a device that requests an MSI or MSI-X. In the past we used 'xen_gsi_from_irq' since that function would return an Xen PIRQ or GSI depending on the provided IRQ. Now that we have seperated that we need to use the correct function. [v2: Deal with rebase on stable/irq.cleanup] Signed-off-by: Konrad Rzeszutek Wilk

xen/irq: Add support to check if IRQ line is shared with other domains.

2011-04-14T15:17:54Z

We do this via the PHYSDEVOP_irq_status_query support hypervisor call. We will get a positive value if another domain has binded its PIRQ to the specified GSI (IRQ line). [v2: Deal with v2.6.37-rc1 rebase fallout] [v3: Deal with stable/irq.cleanup fallout] [v4: xen_ignore_irq->xen_test_irq_shared] Signed-off-by: Konrad Rzeszutek Wilk

xen/irq: Check if the PCI device is owned by a domain different than DOMID_SELF.

2011-04-14T15:17:36Z

We check if there is a domain owner for the PCI device. In case of failure (meaning no domain has registered for this device) we make DOMID_SELF the owner. Signed-off-by: Konrad Rzeszutek Wilk [v2: deal with rebasing on v2.6.37-1] [v3: deal with rebasing on stable/irq.cleanup] [v4: deal with rebasing on stable/irq.ween_of_nr_irqs] [v5: deal with rebasing on v2.6.39-rc3] Signed-off-by: Jeremy Fitzhardinge Acked-by: Xiantao Zhang

Merge branches 'stable/irq.fairness' and 'stable/irq.ween_of_nr_irqs' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen

2011-03-18T01:27:49Z

* 'stable/irq.fairness' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen: events: Remove redundant clear of l2i at end of round-robin loop xen: events: Make round-robin scan fairer by snapshotting each l2 word once only xen: events: Clean up round-robin evtchn scan. xen: events: Make last processed event channel a per-cpu variable. xen: events: Process event channels notifications in round-robin order. * 'stable/irq.ween_of_nr_irqs' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen: xen: events: Fix compile error if CONFIG_SMP is not defined. xen: events: correct locking in xen_irq_from_pirq xen: events: propagate irq allocation failure instead of panicking xen: events: do not workaround too-small nr_irqs xen: events: remove use of nr_irqs as upper bound on number of pirqs xen: events: dynamically allocate irq info structures xen: events: maintain a list of Xen interrupts xen: events: push setup of irq<->{evtchn,ipi,virq,pirq} maps into irq_info init functions xen: events: turn irq_info constructors into initialiser functions xen: events: use per-cpu variable for cpu_evtchn_mask xen: events: refactor GSI pirq bindings functions xen: events: rename restore_cpu_pirqs -> restore_pirqs xen: events: remove unused public functions xen: events: fix xen_map_pirq_gsi error return xen: events: simplify comment xen: events: separate two unrelated halves of if condition Fix up trivial conflicts in drivers/xen/events.c