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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 09/13] xen: implement 3-level event channel routines
Only do_upcall, debug_interrupt and unmask_evtchn are required.
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
drivers/xen/events.c | 291 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 291 insertions(+)
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 30ca620..d953e81 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -51,6 +51,9 @@
#include <xen/interface/hvm/hvm_op.h>
#include <xen/interface/hvm/params.h>
+/* Helper macro(s) */
+#define LONG_BITORDER (BITS_PER_LONG == 64 ? 6 : 5)
+
/* N-level event channel, starting from 2 */
unsigned int evtchn_level = 2;
EXPORT_SYMBOL_GPL(evtchn_level);
@@ -61,6 +64,9 @@ EXPORT_SYMBOL_GPL(nr_event_channels);
static unsigned long *evtchn_pending;
static unsigned long *evtchn_mask;
+/* 2nd level selector for 3-level event channel */
+static DEFINE_PER_CPU(unsigned long[sizeof(unsigned long) * 8], evtchn_sel_l2);
+
/*
* 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.
@@ -396,6 +402,28 @@ static inline void __unmask_local_port_l2(int port)
vcpu_info->evtchn_upcall_pending = 1;
}
+static inline void __unmask_local_port_l3(int port)
+{
+ struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
+ int cpu = smp_processor_id();
+ unsigned int l1bit = port >> (LONG_BITORDER << 1);
+ unsigned int l2bit = port >> LONG_BITORDER;
+
+ sync_clear_bit(port, &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, &evtchn_pending[0]) &&
+ !sync_test_and_set_bit(l2bit,
+ &per_cpu(evtchn_sel_l2, cpu)[0]) &&
+ !sync_test_and_set_bit(l1bit,
+ &vcpu_info->evtchn_pending_sel))
+ vcpu_info->evtchn_upcall_pending = 1;
+}
+
static void unmask_evtchn(int port)
{
unsigned int cpu = get_cpu();
@@ -411,6 +439,9 @@ static void unmask_evtchn(int port)
case 2:
__unmask_local_port_l2(port);
break;
+ case 3:
+ __unmask_local_port_l3(port);
+ break;
default:
BUG();
}
@@ -1185,6 +1216,7 @@ void xen_send_IPI_one(unsigned int cpu, enum ipi_vector
vector)
}
static irqreturn_t xen_debug_interrupt_l2(int irq, void *dev_id);
+static irqreturn_t xen_debug_interrupt_l3(int irq, void *dev_id);
irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
{
@@ -1215,6 +1247,9 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
case 2:
rc = xen_debug_interrupt_l2(irq, dev_id);
break;
+ case 3:
+ rc = xen_debug_interrupt_l3(irq, dev_id);
+ break;
default:
BUG();
}
@@ -1285,8 +1320,109 @@ static irqreturn_t xen_debug_interrupt_l2(int irq, void
*dev_id)
return IRQ_HANDLED;
}
+static irqreturn_t xen_debug_interrupt_l3(int irq, void *dev_id)
+{
+ int cpu = smp_processor_id();
+ unsigned long *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);
+ unsigned long nr_elems = NR_EVENT_CHANNELS_L3 / BITS_PER_LONG;
+ int i;
+ struct vcpu_info *v;
+
+ v = per_cpu(xen_vcpu, cpu);
+
+ printk(KERN_DEBUG "\npending (only show words which have bits set to
1):\n ");
+ for (i = nr_elems-1; i >= 0; i--)
+ if (evtchn_pending[i] != 0UL) {
+ printk(KERN_DEBUG " word index %d %0*lx\n",
+ i,
+ (int)sizeof(evtchn_pending[0])*2,
+ evtchn_pending[i]);
+ }
+
+ printk(KERN_DEBUG "\nglobal mask (only show words which have bits set
to 0):\n ");
+ for (i = nr_elems-1; i >= 0; i--)
+ if (evtchn_mask[i] != ~0UL) {
+ printk(KERN_DEBUG " word index %d %0*lx\n",
+ i,
+ (int)sizeof(evtchn_mask[0])*2,
+ evtchn_mask[i]);
+ }
+
+ printk(KERN_DEBUG "\nglobally unmasked (only show result words which
have bits set to 1):\n ");
+ for (i = nr_elems-1; i >= 0; i--)
+ if ((evtchn_pending[i] & ~evtchn_mask[i]) != 0UL) {
+ printk(KERN_DEBUG " word index %d %0*lx\n",
+ i,
+ (int)(sizeof(evtchn_mask[0])*2),
+ evtchn_pending[i] & ~evtchn_mask[i]);
+ }
+
+ printk(KERN_DEBUG "\nlocal cpu%d mask (only show words which have bits
set to 1):\n ", cpu);
+ for (i = (NR_EVENT_CHANNELS_L3/BITS_PER_LONG)-1; i >= 0; i--)
+ if (cpu_evtchn[i] != 0UL) {
+ printk(KERN_DEBUG " word index %d %0*lx\n",
+ i,
+ (int)(sizeof(cpu_evtchn[0])*2),
+ cpu_evtchn[i]);
+ }
+
+ printk(KERN_DEBUG "\nlocally unmasked (only show result words which
have bits set to 1):\n ");
+ for (i = nr_elems-1; i >= 0; i--) {
+ unsigned long pending = evtchn_pending[i]
+ & ~evtchn_mask[i]
+ & cpu_evtchn[i];
+ if (pending != 0UL) {
+ printk(KERN_DEBUG " word index %d %0*lx\n",
+ i,
+ (int)(sizeof(evtchn_mask[0])*2),
+ pending);
+ }
+ }
+
+ printk(KERN_DEBUG "\npending list:\n");
+ for (i = 0; i < NR_EVENT_CHANNELS_L3; i++) {
+ if (sync_test_bit(i, evtchn_pending)) {
+ int word_idx = i / (BITS_PER_LONG * BITS_PER_LONG);
+ int word_idx_l2 = i / BITS_PER_LONG;
+ printk(KERN_DEBUG " %d: event %d -> irq %d%s%s%s%s\n",
+ cpu_from_evtchn(i), i,
+ evtchn_to_irq[i],
+ !sync_test_bit(word_idx, &v->evtchn_pending_sel)
+ ? "" : " l1-clear",
+ !sync_test_bit(word_idx_l2,
per_cpu(evtchn_sel_l2, cpu))
+ ? "" : " l2-clear",
+ sync_test_bit(i, evtchn_mask)
+ ? "" : " globally-masked",
+ sync_test_bit(i, cpu_evtchn)
+ ? "" : " locally-masked");
+ }
+ }
+
+ return IRQ_HANDLED;
+}
+
+/* The following per-cpu variables are used to save current state of event
+ * processing loop.
+ *
+ * 2-level event channel:
+ * current_word_idx is the bit index in L1 selector indicating the currently
+ * processing word in shared bitmap.
+ * current_bit_idx is the bit index in the currently processing word in shared
+ * bitmap.
+ * N.B. current_word_idx_l2 is not used.
+ *
+ * 3-level event channel:
+ * current_word_idx is the bit index in L1 selector indicating the currently
+ * processing word in L2 selector.
+ * current_word_idx_l2 is the bit index in L2 selector word indicating the
+ * currently processing word in shared bitmap.
+ * current_bit_idx is the bit index in the currently processing word in shared
+ * bitmap.
+ *
+ */
static DEFINE_PER_CPU(unsigned, xed_nesting_count);
static DEFINE_PER_CPU(unsigned int, current_word_idx);
+static DEFINE_PER_CPU(unsigned int, current_word_idx_l2);
static DEFINE_PER_CPU(unsigned int, current_bit_idx);
/*
@@ -1409,6 +1545,155 @@ out:
put_cpu();
}
+/*
+ * In the 3-level event channel implementation, the first level is a
+ * bitset of words which contain pending bits in the second level.
+ * The second level is another bitsets which contain pending bits in
+ * the third level. The third level is a bit set of pending events
+ * themselves.
+ */
+static void __xen_evtchn_do_upcall_l3(void)
+{
+ struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
+ unsigned count;
+ int start_word_idx_l1, start_word_idx_l2, start_bit_idx;
+ int word_idx_l1, word_idx_l2, bit_idx;
+ int i, j;
+ int cpu = get_cpu();
+
+ do {
+ unsigned long pending_words_l1;
+
+ vcpu_info->evtchn_upcall_pending = 0;
+
+ if (__this_cpu_inc_return(xed_nesting_count) - 1)
+ 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
+ /* here we get l1 pending selector */
+ pending_words_l1 = xchg(&vcpu_info->evtchn_pending_sel, 0);
+
+ start_word_idx_l1 = __this_cpu_read(current_word_idx);
+ start_word_idx_l2 = __this_cpu_read(current_word_idx_l2);
+ start_bit_idx = __this_cpu_read(current_bit_idx);
+
+ word_idx_l1 = start_word_idx_l1;
+
+ /* loop through l1, try to pick up l2 */
+ for (i = 0; pending_words_l1 != 0; i++) {
+ unsigned long words_l1;
+ unsigned long pending_words_l2;
+
+ words_l1 = MASK_LSBS(pending_words_l1, word_idx_l1);
+
+ if (words_l1 == 0) {
+ word_idx_l1 = 0;
+ start_word_idx_l2 = 0;
+ continue;
+ }
+
+ word_idx_l1 = __ffs(words_l1);
+
+ pending_words_l2 =
+ xchg(&per_cpu(evtchn_sel_l2, cpu)[word_idx_l1],
+ 0);
+
+ word_idx_l2 = 0;
+ if (word_idx_l1 == start_word_idx_l1) {
+ if (i == 0)
+ word_idx_l2 = start_word_idx_l2;
+ else
+ word_idx_l2 &= (1UL <<
start_word_idx_l2) - 1;
+ }
+
+ for (j = 0; pending_words_l2 != 0; j++) {
+ unsigned long pending_bits;
+ unsigned long words_l2;
+ unsigned long idx;
+
+ words_l2 = MASK_LSBS(pending_words_l2,
+ word_idx_l2);
+
+ if (words_l2 == 0) {
+ word_idx_l2 = 0;
+ bit_idx = 0;
+ continue;
+ }
+
+ word_idx_l2 = __ffs(words_l2);
+
+ idx = word_idx_l1*BITS_PER_LONG+word_idx_l2;
+ pending_bits =
+ active_evtchns(cpu, idx);
+
+ bit_idx = 0;
+ if (word_idx_l2 == start_word_idx_l2) {
+ if (j == 0)
+ bit_idx = start_bit_idx;
+ else
+ bit_idx &=
(1UL<<start_bit_idx)-1;
+ }
+
+ /* process port */
+ do {
+ unsigned long bits;
+ int port, irq;
+ struct irq_desc *desc;
+
+ bits = MASK_LSBS(pending_bits, bit_idx);
+
+ if (bits == 0)
+ break;
+
+ bit_idx = __ffs(bits);
+
+ port = (word_idx_l1 << (LONG_BITORDER
<< 1)) +
+ (word_idx_l2 << LONG_BITORDER) +
+ bit_idx;
+
+ irq = evtchn_to_irq[port];
+
+ if (irq != -1) {
+ desc = irq_to_desc(irq);
+ if (desc)
+
generic_handle_irq_desc(irq, desc);
+ }
+
+ bit_idx = (bit_idx + 1) % BITS_PER_LONG;
+
+ __this_cpu_write(current_bit_idx,
bit_idx);
+ __this_cpu_write(current_word_idx_l2,
+ bit_idx ? word_idx_l2 :
+ (word_idx_l2+1) %
BITS_PER_LONG);
+ __this_cpu_write(current_word_idx_l2,
+ word_idx_l2 ?
word_idx_l1 :
+ (word_idx_l1+1) %
BITS_PER_LONG);
+ } while (bit_idx != 0);
+
+ if ((word_idx_l2 != start_word_idx_l2) || (j !=
0))
+ pending_words_l2 &= ~(1UL <<
word_idx_l2);
+
+ word_idx_l2 = (word_idx_l2 + 1) % BITS_PER_LONG;
+ }
+
+ if ((word_idx_l1 != start_word_idx_l1) || (i != 0))
+ pending_words_l1 &= ~(1UL << word_idx_l1);
+
+ word_idx_l1 = (word_idx_l1 + 1) % BITS_PER_LONG;
+ }
+
+ BUG_ON(!irqs_disabled());
+ count = __this_cpu_read(xed_nesting_count);
+ __this_cpu_write(xed_nesting_count, 0);
+ } while (count != 1 || vcpu_info->evtchn_upcall_pending);
+
+out:
+ put_cpu();
+}
+
void xen_evtchn_do_upcall(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
@@ -1420,6 +1705,9 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
case 2:
__xen_evtchn_do_upcall_l2();
break;
+ case 3:
+ __xen_evtchn_do_upcall_l3();
+ break;
default:
BUG();
}
@@ -1434,6 +1722,9 @@ void xen_hvm_evtchn_do_upcall(void)
case 2:
__xen_evtchn_do_upcall_l2();
break;
+ case 3:
+ __xen_evtchn_do_upcall_l3();
+ break;
default:
BUG();
}
--
1.7.10.4
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