- 根目录:
- drivers
- xen
- events
- events_2l.c
/*
* Xen event channels (2-level ABI)
*
* Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
*/
#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
#include <linux/linkage.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <asm/sync_bitops.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <xen/xen.h>
#include <xen/xen-ops.h>
#include <xen/events.h>
#include <xen/interface/xen.h>
#include <xen/interface/event_channel.h>
#include "events_internal.h"
/*
* Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be
* careful to only use bitops which allow for this (e.g
* test_bit/find_first_bit and friends but not __ffs) and to pass
* BITS_PER_EVTCHN_WORD as the bitmask length.
*/
#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)
/*
* Make a bitmask (i.e. unsigned long *) of a xen_ulong_t
* array. Primarily to avoid long lines (hence the terse name).
*/
#define BM(x) (unsigned long *)(x)
/* Find the first set bit in a evtchn mask */
#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD)
static DEFINE_PER_CPU(xen_ulong_t [EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD],
cpu_evtchn_mask);
static unsigned evtchn_2l_max_channels(void)
{
return EVTCHN_2L_NR_CHANNELS;
}
static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu)
{
clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu)));
set_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
}
static void evtchn_2l_clear_pending(unsigned port)
{
struct shared_info *s = HYPERVISOR_shared_info;
sync_clear_bit(port, BM(&s->evtchn_pending[0]));
}
static void evtchn_2l_set_pending(unsigned port)
{
struct shared_info *s = HYPERVISOR_shared_info;
sync_set_bit(port, BM(&s->evtchn_pending[0]));
}
static bool evtchn_2l_is_pending(unsigned port)
{
struct shared_info *s = HYPERVISOR_shared_info;
return sync_test_bit(port, BM(&s->evtchn_pending[0]));
}
static bool evtchn_2l_test_and_set_mask(unsigned port)
{
struct shared_info *s = HYPERVISOR_shared_info;
return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
}
static void evtchn_2l_mask(unsigned port)
{
struct shared_info *s = HYPERVISOR_shared_info;
sync_set_bit(port, BM(&s->evtchn_mask[0]));
}
static void evtchn_2l_unmask(unsigned port)
{
struct shared_info *s = HYPERVISOR_shared_info;
unsigned int cpu = get_cpu();
int do_hypercall = 0, evtchn_pending = 0;
BUG_ON(!irqs_disabled());
if (unlikely((cpu != cpu_from_evtchn(port))))
do_hypercall = 1;
else {
/*
* Need to clear the mask before checking pending to
* avoid a race with an event becoming pending.
*
* EVTCHNOP_unmask will only trigger an upcall if the
* mask bit was set, so if a hypercall is needed
* remask the event.
*/
sync_clear_bit(port, BM(&s->evtchn_mask[0]));
evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));
if (unlikely(evtchn_pending && xen_hvm_domain())) {
sync_set_bit(port, BM(&s->evtchn_mask[0]));
do_hypercall = 1;
}
}
/* Slow path (hypercall) if this is a non-local port or if this is
* an hvm domain and an event is pending (hvm domains don't have
* their own implementation of irq_enable). */
if (do_hypercall) {
struct evtchn_unmask unmask = { .port = port };
(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
} else {
struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
/*
* 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 (evtchn_pending &&
!sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD,
BM(&vcpu_info->evtchn_pending_sel)))
vcpu_info->evtchn_upcall_pending = 1;
}
put_cpu();
}
static DEFINE_PER_CPU(unsigned int, current_word_idx);
static DEFINE_PER_CPU(unsigned int, current_bit_idx);
/*
* Mask out the i least significant bits of w
*/
#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))
static inline xen_ulong_t active_evtchns(unsigned int cpu,
struct shared_info *sh,
unsigned int idx)
{
return sh->evtchn_pending[idx] &
per_cpu(cpu_evtchn_mask, cpu)[idx] &
~sh->evtchn_mask[idx];
}
/*
* Search the CPU's 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.
*/
static void evtchn_2l_handle_events(unsigned cpu)
{
int irq;
xen_ulong_t pending_words;
xen_ulong_t pending_bits;
int start_word_idx, start_bit_idx;
int word_idx, bit_idx;
int i;
struct shared_info *s = HYPERVISOR_shared_info;
struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
/* Timer interrupt has highest priority. */
irq = irq_from_virq(cpu, VIRQ_TIMER);
if (irq != -1) {
unsigned int evtchn = evtchn_from_irq(irq);
word_idx = evtchn / BITS_PER_LONG;
bit_idx = evtchn % BITS_PER_LONG;
if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx))
generic_handle_irq(irq);
}
/*
* Master flag must be cleared /before/ clearing
* selector flag. xchg_xen_ulong must contain an
* appropriate barrier.
*/
pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0);
start_word_idx = __this_cpu_read(current_word_idx);
start_bit_idx = __this_cpu_read(current_bit_idx);
word_idx = start_word_idx;
for (i = 0; pending_words != 0; i++) {
xen_ulong_t words;
words = MASK_LSBS(pending_words, word_idx);
/*
* If we masked out all events, wrap to beginning.
*/
if (words == 0) {
word_idx = 0;
bit_idx = 0;
continue;
}
word_idx = EVTCHN_FIRST_BIT(words);
pending_bits = active_evtchns(cpu, s, word_idx);
bit_idx = 0; /* usually scan entire word from start */
/*
* We scan the starting word in two parts.
*
* 1st time: start in the middle, scanning the
* upper bits.
*
* 2nd time: scan the whole word (not just the
* parts skipped in the first pass) -- if an
* event in the previously scanned bits is
* pending again it would just be scanned on
* the next loop anyway.
*/
if (word_idx == start_word_idx) {
if (i == 0)
bit_idx = start_bit_idx;
}
do {
xen_ulong_t bits;
int port;
bits = MASK_LSBS(pending_bits, bit_idx);
/* If we masked out all events, move on. */
if (bits == 0)
break;
bit_idx = EVTCHN_FIRST_BIT(bits);
/* Process port. */
port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;
irq = get_evtchn_to_irq(port);
if (irq != -1)
generic_handle_irq(irq);
bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD;
/* Next caller starts at last processed + 1 */
__this_cpu_write(current_word_idx,
bit_idx ? word_idx :
(word_idx+1) % BITS_PER_EVTCHN_WORD);
__this_cpu_write(current_bit_idx, bit_idx);
} while (bit_idx != 0);
/* Scan start_l1i twice; all others once. */
if ((word_idx != start_word_idx) || (i != 0))
pending_words &= ~(1UL << word_idx);
word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD;
}
}
irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
{
struct shared_info *sh = HYPERVISOR_shared_info;
int cpu = smp_processor_id();
xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
int i;
unsigned long flags;
static DEFINE_SPINLOCK(debug_lock);
struct vcpu_info *v;
spin_lock_irqsave(&debug_lock, flags);
printk("\nvcpu %d\n ", cpu);
for_each_online_cpu(i) {
int pending;
v = per_cpu(xen_vcpu, i);
pending = (get_irq_regs() && i == cpu)
? xen_irqs_disabled(get_irq_regs())
: v->evtchn_upcall_mask;
printk("%d: masked=%d pending=%d event_sel %0*"PRI_xen_ulong"\n ", i,
pending, v->evtchn_upcall_pending,
(int)(sizeof(v->evtchn_pending_sel)*2),
v->evtchn_pending_sel);
}
v = per_cpu(xen_vcpu, cpu);
printk("\npending:\n ");
for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)
printk("%0*"PRI_xen_ulong"%s",
(int)sizeof(sh->evtchn_pending[0])*2,
sh->evtchn_pending[i],
i % 8 == 0 ? "\n " : " ");
printk("\nglobal mask:\n ");
for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(sh->evtchn_mask[0])*2),
sh->evtchn_mask[i],
i % 8 == 0 ? "\n " : " ");
printk("\nglobally unmasked:\n ");
for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)
printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(sh->evtchn_mask[0])*2),
sh->evtchn_pending[i] & ~sh->evtchn_mask[i],
i % 8 == 0 ? "\n " : " ");
printk("\nlocal cpu%d mask:\n ", cpu);
for (i = (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)
printk("%0*"PRI_xen_ulong"%s", (int)(sizeof(cpu_evtchn[0])*2),
cpu_evtchn[i],
i % 8 == 0 ? "\n " : " ");
printk("\nlocally unmasked:\n ");
for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {
xen_ulong_t pending = sh->evtchn_pending[i]
& ~sh->evtchn_mask[i]
& cpu_evtchn[i];
printk("%0*"PRI_xen_ulong"%s",
(int)(sizeof(sh->evtchn_mask[0])*2),
pending, i % 8 == 0 ? "\n " : " ");
}
printk("\npending list:\n");
for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) {
if (sync_test_bit(i, BM(sh->evtchn_pending))) {
int word_idx = i / BITS_PER_EVTCHN_WORD;
printk(" %d: event %d -> irq %d%s%s%s\n",
cpu_from_evtchn(i), i,
get_evtchn_to_irq(i),
sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
? "" : " l2-clear",
!sync_test_bit(i, BM(sh->evtchn_mask))
? "" : " globally-masked",
sync_test_bit(i, BM(cpu_evtchn))
? "" : " locally-masked");
}
}
spin_unlock_irqrestore(&debug_lock, flags);
return IRQ_HANDLED;
}
static void evtchn_2l_resume(void)
{
int i;
for_each_online_cpu(i)
memset(per_cpu(cpu_evtchn_mask, i), 0, sizeof(xen_ulong_t) *
EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD);
}
static const struct evtchn_ops evtchn_ops_2l = {
.max_channels = evtchn_2l_max_channels,
.nr_channels = evtchn_2l_max_channels,
.bind_to_cpu = evtchn_2l_bind_to_cpu,
.clear_pending = evtchn_2l_clear_pending,
.set_pending = evtchn_2l_set_pending,
.is_pending = evtchn_2l_is_pending,
.test_and_set_mask = evtchn_2l_test_and_set_mask,
.mask = evtchn_2l_mask,
.unmask = evtchn_2l_unmask,
.handle_events = evtchn_2l_handle_events,
.resume = evtchn_2l_resume,
};
void __init xen_evtchn_2l_init(void)
{
pr_info("Using 2-level ABI\n");
evtchn_ops = &evtchn_ops_2l;
}