/*
* Xen event channels
*
* Xen models interrupts with abstract event channels. Because each
* domain gets 1024 event channels, but NR_IRQ is not that large, we
* must dynamically map irqs<->event channels. The event channels
* interface with the rest of the kernel by defining a xen interrupt
* chip. When an event is recieved, it is mapped to an irq and sent
* through the normal interrupt processing path.
*
* There are four kinds of events which can be mapped to an event
* channel:
*
* 1. Inter-domain notifications. This includes all the virtual
* device events, since they're driven by front-ends in another domain
* (typically dom0).
* 2. VIRQs, typically used for timers. These are per-cpu events.
* 3. IPIs.
* 4. Hardware interrupts. Not supported at present.
*
* Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
*/
#include <linux/linkage.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/string.h>
#include <asm/ptrace.h>
#include <asm/irq.h>
#include <asm/sync_bitops.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <xen/xen-ops.h>
#include <xen/events.h>
#include <xen/interface/xen.h>
#include <xen/interface/event_channel.h>
/*
* This lock protects updates to the following mapping and reference-count
* arrays. The lock does not need to be acquired to read the mapping tables.
*/
static DEFINE_SPINLOCK(irq_mapping_update_lock);
/* IRQ <-> VIRQ mapping. */
static DEFINE_PER_CPU(int, virq_to_irq[NR_VIRQS]) = {[0 ... NR_VIRQS-1] = -1};
/* IRQ <-> IPI mapping */
static DEFINE_PER_CPU(int, ipi_to_irq[XEN_NR_IPIS]) = {[0 ... XEN_NR_IPIS-1] = -1};
/* Packed IRQ information: binding type, sub-type index, and event channel. */
struct packed_irq
{
unsigned short evtchn;
unsigned char index;
unsigned char type;
};
static struct packed_irq irq_info[NR_IRQS];
/* Binding types. */
enum {
IRQT_UNBOUND,
IRQT_PIRQ,
IRQT_VIRQ,
IRQT_IPI,
IRQT_EVTCHN
};
/* Convenient shorthand for packed representation of an unbound IRQ. */
#define IRQ_UNBOUND mk_irq_info(IRQT_UNBOUND, 0, 0)
static int evtchn_to_irq[NR_EVENT_CHANNELS] = {
[0 ... NR_EVENT_CHANNELS-1] = -1
};
static unsigned long cpu_evtchn_mask[NR_CPUS][NR_EVENT_CHANNELS/BITS_PER_LONG];
static u8 cpu_evtchn[NR_EVENT_CHANNELS];
/* Reference counts for bindings to IRQs. */
static int irq_bindcount[NR_IRQS];
/* Xen will never allocate port zero for any purpose. */
#define VALID_EVTCHN(chn) ((chn) != 0)
static struct irq_chip xen_dynamic_chip;
/* Constructor for packed IRQ information. */
static inline struct packed_irq mk_irq_info(u32 type, u32 index, u32 evtchn)
{
return (struct packed_irq) { evtchn, index, type };
}
/*
* Accessors for packed IRQ information.
*/
static inline unsigned int evtchn_from_irq(int irq)
{
return irq_info[irq].evtchn;
}
static inline unsigned int index_from_irq(int irq)
{
return irq_info[irq].index;
}
static inline unsigned int type_from_irq(int irq)
{
return irq_info[irq].type;
}
static inline unsigned long active_evtchns(unsigned int cpu,
struct shared_info *sh,
unsigned int idx)
{
return (sh->evtchn_pending[idx] &
cpu_evtchn_mask[cpu][idx] &
~sh->evtchn_mask[idx]);
}
static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu)
{
int irq = evtchn_to_irq[chn];
BUG_ON(irq == -1);
#ifdef CONFIG_SMP
irq_to_desc(irq)->affinity = cpumask_of_cpu(cpu);
#endif
__clear_bit(chn, cpu_evtchn_mask[cpu_evtchn[chn]]);
__set_bit(chn, cpu_evtchn_mask[cpu]);
cpu_evtchn[chn] = cpu;
}
static void init_evtchn_cpu_bindings(void)
{
#ifdef CONFIG_SMP
struct irq_desc *desc;
int i;
/* By default all event channels notify CPU#0. */
for_each_irq_desc(i, desc) {
desc->affinity = cpumask_of_cpu(0);
}
#endif
memset(cpu_evtchn, 0, sizeof(cpu_evtchn));
memset(cpu_evtchn_mask[0], ~0, sizeof(cpu_evtchn_mask[0]));
}
static inline unsigned int cpu_from_evtchn(unsigned int evtchn)
{
return cpu_evtchn[evtchn];
}
static inline void clear_evtchn(int port)
{
struct shared_info *s = HYPERVISOR_shared_info;
sync_clear_bit(port, &s->evtchn_pending[0]);
}
static inline void set_evtchn(int port)
{
struct shared_info *s = HYPERVISOR_shared_info;
sync_set_bit(port, &s->evtchn_pending[0]);
}
static inline int test_evtchn(int port)
{
struct shared_info *s = HYPERVISOR_shared_info;
return sync_test_bit(port, &s->evtchn_pending[0]);
}
/**
* notify_remote_via_irq - send event to remote end of event channel via irq
* @irq: irq of event channel to send event to
*
* Unlike notify_remote_via_evtchn(), this is safe to use across
* save/restore. Notifications on a broken connection are silently
* dropped.
*/
void notify_remote_via_irq(int irq)
{
int evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn))
notify_remote_via_evtchn(evtchn);
}
EXPORT_SYMBOL_GPL(notify_remote_via_irq);
static void mask_evtchn(int port)
{
struct shared_info *s = HYPERVISOR_shared_info;
sync_set_bit(port, &s->evtchn_mask[0]);
}
static void unmask_evtchn(int port)
{
struct shared_info *s = HYPERVISOR_shared_info;
unsigned int cpu = get_cpu();
BUG_ON(!irqs_disabled());
/* Slow path (hypercall) if this is a non-local port. */
if (unlikely(cpu != cpu_from_evtchn(port))) {
struct evtchn_unmask unmask = { .port = port };
(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
} else {
struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
sync_clear_bit(port, &s->evtchn_mask[0]);
/*
* The following is basically the equivalent of
* 'hw_resend_irq'. Just like a real IO-APIC we 'lose
* the interrupt edge' if the channel is masked.
*/
if (sync_test_bit(port, &s->evtchn_pending[0]) &&
!sync_test_and_set_bit(port / BITS_PER_LONG,
&vcpu_info->evtchn_pending_sel))
vcpu_info->evtchn_upcall_pending = 1;
}
put_cpu();
}
static int find_unbound_irq(void)
{
int irq;
struct irq_desc *desc;
/* Only allocate from dynirq range */
for (irq = 0; irq < nr_irqs; irq++)
if (irq_bindcount[irq] == 0)
break;
if (irq == nr_irqs)
panic("No available IRQ to bind to: increase nr_irqs!\n");
desc = irq_to_desc_alloc_cpu(irq, 0);
if (WARN_ON(desc == NULL))
return -1;
return irq;
}
int bind_evtchn_to_irq(unsigned int evtchn)
{
int irq;
spin_lock(&irq_mapping_update_lock);
irq = evtchn_to_irq[evtchn];
if (irq == -1) {
irq = find_unbound_irq();
dynamic_irq_init(irq);
set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
handle_level_irq, "event");
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_EVTCHN, 0, evtchn);
}
irq_bindcount[irq]++;
spin_unlock(&irq_mapping_update_lock);
return irq;
}
EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);
static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
{
struct evtchn_bind_ipi bind_ipi;
int evtchn, irq;
spin_lock(&irq_mapping_update_lock);
irq = per_cpu(ipi_to_irq, cpu)[ipi];
if (irq == -1) {
irq = find_unbound_irq();
if (irq < 0)
goto out;
dynamic_irq_init(irq);
set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
handle_level_irq, "ipi");
bind_ipi.vcpu = cpu;
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
&bind_ipi) != 0)
BUG();
evtchn = bind_ipi.port;
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);
per_cpu(ipi_to_irq, cpu)[ipi] = irq;
bind_evtchn_to_cpu(evtchn, cpu);
}
irq_bindcount[irq]++;
out:
spin_unlock(&irq_mapping_update_lock);
return irq;
}
static int bind_virq_to_irq(unsigned int virq, unsigned int cpu)
{
struct evtchn_bind_virq bind_virq;
int evtchn, irq;
spin_lock(&irq_mapping_update_lock);
irq = per_cpu(virq_to_irq, cpu)[virq];
if (irq == -1) {
bind_virq.virq = virq;
bind_virq.vcpu = cpu;
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
&bind_virq) != 0)
BUG();
evtchn = bind_virq.port;
irq = find_unbound_irq();
dynamic_irq_init(irq);
set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
handle_level_irq, "virq");
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn);
per_cpu(virq_to_irq, cpu)[virq] = irq;
bind_evtchn_to_cpu(evtchn, cpu);
}
irq_bindcount[irq]++;
spin_unlock(&irq_mapping_update_lock);
return irq;
}
static void unbind_from_irq(unsigned int irq)
{
struct evtchn_close close;
int evtchn = evtchn_from_irq(irq);
spin_lock(&irq_mapping_update_lock);
if ((--irq_bindcount[irq] == 0) && VALID_EVTCHN(evtchn)) {
close.port = evtchn;
if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
BUG();
switch (type_from_irq(irq)) {
case IRQT_VIRQ:
per_cpu(virq_to_irq, cpu_from_evtchn(evtchn))
[index_from_irq(irq)] = -1;
break;
case IRQT_IPI:
per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn))
[index_from_irq(irq)] = -1;
break;
default:
break;
}
/* Closed ports are implicitly re-bound to VCPU0. */
bind_evtchn_to_cpu(evtchn, 0);
evtchn_to_irq[evtchn] = -1;
irq_info[irq] = IRQ_UNBOUND;
dynamic_irq_cleanup(irq);
}
spin_unlock(&irq_mapping_update_lock);
}
int bind_evtchn_to_irqhandler(unsigned int evtchn,
irq_handler_t handler,
unsigned long irqflags,
const char *devname, void *dev_id)
{
unsigned int irq;
int retval;
irq = bind_evtchn_to_irq(evtchn);
retval = request_irq(irq, handler, irqflags, devname, dev_id);
if (retval != 0) {
unbind_from_irq(irq);
return retval;
}
return irq;
}
EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler);
int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu,
irq_handler_t handler,
unsigned long irqflags, const char *devname, void *dev_id)
{
unsigned int irq;
int retval;
irq = bind_virq_to_irq(virq, cpu);
retval = request_irq(irq, handler, irqflags, devname, dev_id);
if (retval != 0) {
unbind_from_irq(irq);
return retval;
}
return irq;
}
EXPORT_SYMBOL_GPL(bind_virq_to_irqhandler);
int bind_ipi_to_irqhandler(enum ipi_vector ipi,
unsigned int cpu,
irq_handler_t handler,
unsigned long irqflags,
const char *devname,
void *dev_id)
{
int irq, retval;
irq = bind_ipi_to_irq(ipi, cpu);
if (irq < 0)
return irq;
retval = request_irq(irq, handler, irqflags, devname, dev_id);
if (retval != 0) {
unbind_from_irq(irq);
return retval;
}
return irq;
}
void unbind_from_irqhandler(unsigned int irq, void *dev_id)
{
free_irq(irq, dev_id);
unbind_from_irq(irq);
}
EXPORT_SYMBOL_GPL(unbind_from_irqhandler);
void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector)
{
int irq = per_cpu(ipi_to_irq, cpu)[vector];
BUG_ON(irq < 0);
notify_remote_via_irq(irq);
}
irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
{
struct shared_info *sh = HYPERVISOR_shared_info;
int cpu = smp_processor_id();
int i;
unsigned long flags;
static DEFINE_SPINLOCK(debug_lock);
spin_lock_irqsave(&debug_lock, flags);
printk("vcpu %d\n ", cpu);
for_each_online_cpu(i) {
struct vcpu_info *v = per_cpu(xen_vcpu, i);
printk("%d: masked=%d pending=%d event_sel %08lx\n ", i,
(get_irq_regs() && i == cpu) ? xen_irqs_disabled(get_irq_regs()) : v->evtchn_upcall_mask,
v->evtchn_upcall_pending,
v->evtchn_pending_sel);
}
printk("pending:\n ");
for(i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
printk("%08lx%s", sh->evtchn_pending[i],
i % 8 == 0 ? "\n " : " ");
printk("\nmasks:\n ");
for(i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
printk("%08lx%s", sh->evtchn_mask[i],
i % 8 == 0 ? "\n " : " ");
printk("\nunmasked:\n ");
for(i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
printk("%08lx%s", sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
i % 8 == 0 ? "\n " : " ");
printk("\npending list:\n");
for(i = 0; i < NR_EVENT_CHANNELS; i++) {
if (sync_test_bit(i, sh->evtchn_pending)) {
printk(" %d: event %d -> irq %d\n",
cpu_evtchn[i], i,
evtchn_to_irq[i]);
}
}
spin_unlock_irqrestore(&debug_lock, flags);
return IRQ_HANDLED;
}
/*
* Search the CPUs pending events bitmasks. For each one found, map
* the event number to an irq, and feed it into do_IRQ() for
* handling.
*
* Xen uses a two-level bitmap to speed searching. The first level is
* a bitset of words which contain pending event bits. The second
* level is a bitset of pending events themselves.
*/
void xen_evtchn_do_upcall(struct pt_regs *regs)
{
int cpu = get_cpu();
struct shared_info *s = HYPERVISOR_shared_info;
struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu);
static DEFINE_PER_CPU(unsigned, nesting_count);
unsigned count;
do {
unsigned long pending_words;
vcpu_info->evtchn_upcall_pending = 0;
if (__get_cpu_var(nesting_count)++)
goto out;
#ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */
/* Clear master flag /before/ clearing selector flag. */
wmb();
#endif
pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
while (pending_words != 0) {
unsigned long pending_bits;
int word_idx = __ffs(pending_words);
pending_words &= ~(1UL << word_idx);
while ((pending_bits = active_evtchns(cpu, s, word_idx)) != 0) {
int bit_idx = __ffs(pending_bits);
int port = (word_idx * BITS_PER_LONG) + bit_idx;
int irq = evtchn_to_irq[port];
if (irq != -1)
xen_do_IRQ(irq, regs);
}
}
BUG_ON(!irqs_disabled());
count = __get_cpu_var(nesting_count);
__get_cpu_var(nesting_count) = 0;
} while(count != 1);
out:
put_cpu();
}
/* Rebind a new event channel to an existing irq. */
void rebind_evtchn_irq(int evtchn, int irq)
{
/* Make sure the irq is masked, since the new event channel
will also be masked. */
disable_irq(irq);
spin_lock(&irq_mapping_update_lock);
/* After resume the irq<->evtchn mappings are all cleared out */
BUG_ON(evtchn_to_irq[evtchn] != -1);
/* Expect irq to have been bound before,
so the bindcount should be non-0 */
BUG_ON(irq_bindcount[irq] == 0);
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_EVTCHN, 0, evtchn);
spin_unlock(&irq_mapping_update_lock);
/* new event channels are always bound to cpu 0 */
irq_set_affinity(irq, cpumask_of_cpu(0));
/* Unmask the event channel. */
enable_irq(irq);
}
/* Rebind an evtchn so that it gets delivered to a specific cpu */
static void rebind_irq_to_cpu(unsigned irq, unsigned tcpu)
{
struct evtchn_bind_vcpu bind_vcpu;
int evtchn = evtchn_from_irq(irq);
if (!VALID_EVTCHN(evtchn))
return;
/* Send future instances of this interrupt to other vcpu. */
bind_vcpu.port = evtchn;
bind_vcpu.vcpu = tcpu;
/*
* If this fails, it usually just indicates that we're dealing with a
* virq or IPI channel, which don't actually need to be rebound. Ignore
* it, but don't do the xenlinux-level rebind in that case.
*/
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
bind_evtchn_to_cpu(evtchn, tcpu);
}
static void set_affinity_irq(unsigned irq, cpumask_t dest)
{
unsigned tcpu = first_cpu(dest);
rebind_irq_to_cpu(irq, tcpu);
}
int resend_irq_on_evtchn(unsigned int irq)
{
int masked, evtchn = evtchn_from_irq(irq);
struct shared_info *s = HYPERVISOR_shared_info;
if (!VALID_EVTCHN(evtchn))
return 1;
masked = sync_test_and_set_bit(evtchn, s->evtchn_mask);
sync_set_bit(evtchn, s->evtchn_pending);
if (!masked)
unmask_evtchn(evtchn);
return 1;
}
static void enable_dynirq(unsigned int irq)
{
int evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn))
unmask_evtchn(evtchn);
}
static void disable_dynirq(unsigned int irq)
{
int evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn))
mask_evtchn(evtchn);
}
static void ack_dynirq(unsigned int irq)
{
int evtchn = evtchn_from_irq(irq);
move_native_irq(irq);
if (VALID_EVTCHN(evtchn))
clear_evtchn(evtchn);
}
static int retrigger_dynirq(unsigned int irq)
{
int evtchn = evtchn_from_irq(irq);
struct shared_info *sh = HYPERVISOR_shared_info;
int ret = 0;
if (VALID_EVTCHN(evtchn)) {
int masked;
masked = sync_test_and_set_bit(evtchn, sh->evtchn_mask);
sync_set_bit(evtchn, sh->evtchn_pending);
if (!masked)
unmask_evtchn(evtchn);
ret = 1;
}
return ret;
}
static void restore_cpu_virqs(unsigned int cpu)
{
struct evtchn_bind_virq bind_virq;
int virq, irq, evtchn;
for (virq = 0; virq < NR_VIRQS; virq++) {
if ((irq = per_cpu(virq_to_irq, cpu)[virq]) == -1)
continue;
BUG_ON(irq_info[irq].type != IRQT_VIRQ);
BUG_ON(irq_info[irq].index != virq);
/* Get a new binding from Xen. */
bind_virq.virq = virq;
bind_virq.vcpu = cpu;
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
&bind_virq) != 0)
BUG();
evtchn = bind_virq.port;
/* Record the new mapping. */
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn);
bind_evtchn_to_cpu(evtchn, cpu);
/* Ready for use. */
unmask_evtchn(evtchn);
}
}
static void restore_cpu_ipis(unsigned int cpu)
{
struct evtchn_bind_ipi bind_ipi;
int ipi, irq, evtchn;
for (ipi = 0; ipi < XEN_NR_IPIS; ipi++) {
if ((irq = per_cpu(ipi_to_irq, cpu)[ipi]) == -1)
continue;
BUG_ON(irq_info[irq].type != IRQT_IPI);
BUG_ON(irq_info[irq].index != ipi);
/* Get a new binding from Xen. */
bind_ipi.vcpu = cpu;
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
&bind_ipi) != 0)
BUG();
evtchn = bind_ipi.port;
/* Record the new mapping. */
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);
bind_evtchn_to_cpu(evtchn, cpu);
/* Ready for use. */
unmask_evtchn(evtchn);
}
}
/* Clear an irq's pending state, in preparation for polling on it */
void xen_clear_irq_pending(int irq)
{
int evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn))
clear_evtchn(evtchn);
}
void xen_set_irq_pending(int irq)
{
int evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn))
set_evtchn(evtchn);
}
bool xen_test_irq_pending(int irq)
{
int evtchn = evtchn_from_irq(irq);
bool ret = false;
if (VALID_EVTCHN(evtchn))
ret = test_evtchn(evtchn);
return ret;
}
/* Poll waiting for an irq to become pending. In the usual case, the
irq will be disabled so it won't deliver an interrupt. */
void xen_poll_irq(int irq)
{
evtchn_port_t evtchn = evtchn_from_irq(irq);
if (VALID_EVTCHN(evtchn)) {
struct sched_poll poll;
poll.nr_ports = 1;
poll.timeout = 0;
set_xen_guest_handle(poll.ports, &evtchn);
if (HYPERVISOR_sched_op(SCHEDOP_poll, &poll) != 0)
BUG();
}
}
void xen_irq_resume(void)
{
unsigned int cpu, irq, evtchn;
init_evtchn_cpu_bindings();
/* New event-channel space is not 'live' yet. */
for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
mask_evtchn(evtchn);
/* No IRQ <-> event-channel mappings. */
for (irq = 0; irq < nr_irqs; irq++)
irq_info[irq].evtchn = 0; /* zap event-channel binding */
for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
evtchn_to_irq[evtchn] = -1;
for_each_possible_cpu(cpu) {
restore_cpu_virqs(cpu);
restore_cpu_ipis(cpu);
}
}
static struct irq_chip xen_dynamic_chip __read_mostly = {
.name = "xen-dyn",
.mask = disable_dynirq,
.unmask = enable_dynirq,
.ack = ack_dynirq,
.set_affinity = set_affinity_irq,
.retrigger = retrigger_dynirq,
};
void __init xen_init_IRQ(void)
{
int i;
init_evtchn_cpu_bindings();
/* No event channels are 'live' right now. */
for (i = 0; i < NR_EVENT_CHANNELS; i++)
mask_evtchn(i);
/* Dynamic IRQ space is currently unbound. Zero the refcnts. */
for (i = 0; i < nr_irqs; i++)
irq_bindcount[i] = 0;
irq_ctx_init(smp_processor_id());
}
