kernel/linux.git/include/xen/events.h, branch v4.9.331

xen/events: add a new "late EOI" evtchn framework

2020-11-18T17:26:30+00:00

commit 54c9de89895e0a36047fcc4ae754ea5b8655fb9d upstream. In order to avoid tight event channel related IRQ loops add a new framework of "late EOI" handling: the IRQ the event channel is bound to will be masked until the event has been handled and the related driver is capable to handle another event. The driver is responsible for unmasking the event channel via the new function xen_irq_lateeoi(). This is similar to binding an event channel to a threaded IRQ, but without having to structure the driver accordingly. In order to support a future special handling in case a rogue guest is sending lots of unsolicited events, add a flag to xen_irq_lateeoi() which can be set by the caller to indicate the event was a spurious one. This is part of XSA-332. Cc: stable@vger.kernel.org Reported-by: Julien Grall Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Reviewed-by: Stefano Stabellini Reviewed-by: Wei Liu Signed-off-by: Greg Kroah-Hartman

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