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384 lines
11 KiB
384 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Xen event channels (2-level ABI) |
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* |
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* Jeremy Fitzhardinge <[email protected]>, XenSource Inc, 2007 |
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*/ |
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#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
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#include <linux/linkage.h> |
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#include <linux/interrupt.h> |
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#include <linux/irq.h> |
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#include <asm/sync_bitops.h> |
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#include <asm/xen/hypercall.h> |
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#include <asm/xen/hypervisor.h> |
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#include <xen/xen.h> |
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#include <xen/xen-ops.h> |
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#include <xen/events.h> |
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#include <xen/interface/xen.h> |
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#include <xen/interface/event_channel.h> |
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#include "events_internal.h" |
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/* |
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* Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be |
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* careful to only use bitops which allow for this (e.g |
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* test_bit/find_first_bit and friends but not __ffs) and to pass |
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* BITS_PER_EVTCHN_WORD as the bitmask length. |
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*/ |
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#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8) |
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/* |
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* Make a bitmask (i.e. unsigned long *) of a xen_ulong_t |
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* array. Primarily to avoid long lines (hence the terse name). |
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*/ |
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#define BM(x) (unsigned long *)(x) |
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/* Find the first set bit in a evtchn mask */ |
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#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD) |
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#define EVTCHN_MASK_SIZE (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD) |
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static DEFINE_PER_CPU(xen_ulong_t [EVTCHN_MASK_SIZE], cpu_evtchn_mask); |
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static unsigned evtchn_2l_max_channels(void) |
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{ |
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return EVTCHN_2L_NR_CHANNELS; |
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} |
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static void evtchn_2l_remove(evtchn_port_t evtchn, unsigned int cpu) |
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{ |
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clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu))); |
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} |
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static void evtchn_2l_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu, |
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unsigned int old_cpu) |
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{ |
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clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, old_cpu))); |
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set_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu))); |
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} |
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static void evtchn_2l_clear_pending(evtchn_port_t port) |
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{ |
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struct shared_info *s = HYPERVISOR_shared_info; |
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sync_clear_bit(port, BM(&s->evtchn_pending[0])); |
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} |
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static void evtchn_2l_set_pending(evtchn_port_t port) |
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{ |
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struct shared_info *s = HYPERVISOR_shared_info; |
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sync_set_bit(port, BM(&s->evtchn_pending[0])); |
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} |
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static bool evtchn_2l_is_pending(evtchn_port_t port) |
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{ |
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struct shared_info *s = HYPERVISOR_shared_info; |
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return sync_test_bit(port, BM(&s->evtchn_pending[0])); |
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} |
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static void evtchn_2l_mask(evtchn_port_t port) |
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{ |
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struct shared_info *s = HYPERVISOR_shared_info; |
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sync_set_bit(port, BM(&s->evtchn_mask[0])); |
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} |
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static void evtchn_2l_unmask(evtchn_port_t port) |
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{ |
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struct shared_info *s = HYPERVISOR_shared_info; |
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unsigned int cpu = get_cpu(); |
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int do_hypercall = 0, evtchn_pending = 0; |
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BUG_ON(!irqs_disabled()); |
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smp_wmb(); /* All writes before unmask must be visible. */ |
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if (unlikely((cpu != cpu_from_evtchn(port)))) |
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do_hypercall = 1; |
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else { |
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/* |
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* Need to clear the mask before checking pending to |
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* avoid a race with an event becoming pending. |
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* |
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* EVTCHNOP_unmask will only trigger an upcall if the |
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* mask bit was set, so if a hypercall is needed |
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* remask the event. |
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*/ |
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sync_clear_bit(port, BM(&s->evtchn_mask[0])); |
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evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0])); |
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if (unlikely(evtchn_pending && xen_hvm_domain())) { |
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sync_set_bit(port, BM(&s->evtchn_mask[0])); |
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do_hypercall = 1; |
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} |
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} |
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/* Slow path (hypercall) if this is a non-local port or if this is |
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* an hvm domain and an event is pending (hvm domains don't have |
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* their own implementation of irq_enable). */ |
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if (do_hypercall) { |
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struct evtchn_unmask unmask = { .port = port }; |
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(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask); |
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} else { |
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struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); |
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/* |
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* The following is basically the equivalent of |
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* 'hw_resend_irq'. Just like a real IO-APIC we 'lose |
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* the interrupt edge' if the channel is masked. |
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*/ |
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if (evtchn_pending && |
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!sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD, |
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BM(&vcpu_info->evtchn_pending_sel))) |
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vcpu_info->evtchn_upcall_pending = 1; |
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} |
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put_cpu(); |
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} |
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static DEFINE_PER_CPU(unsigned int, current_word_idx); |
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static DEFINE_PER_CPU(unsigned int, current_bit_idx); |
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/* |
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* Mask out the i least significant bits of w |
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*/ |
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#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i)) |
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static inline xen_ulong_t active_evtchns(unsigned int cpu, |
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struct shared_info *sh, |
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unsigned int idx) |
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{ |
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return sh->evtchn_pending[idx] & |
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per_cpu(cpu_evtchn_mask, cpu)[idx] & |
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~sh->evtchn_mask[idx]; |
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} |
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/* |
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* Search the CPU's pending events bitmasks. For each one found, map |
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* the event number to an irq, and feed it into do_IRQ() for handling. |
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* |
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* Xen uses a two-level bitmap to speed searching. The first level is |
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* a bitset of words which contain pending event bits. The second |
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* level is a bitset of pending events themselves. |
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*/ |
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static void evtchn_2l_handle_events(unsigned cpu, struct evtchn_loop_ctrl *ctrl) |
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{ |
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int irq; |
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xen_ulong_t pending_words; |
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xen_ulong_t pending_bits; |
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int start_word_idx, start_bit_idx; |
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int word_idx, bit_idx; |
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int i; |
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struct shared_info *s = HYPERVISOR_shared_info; |
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struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); |
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/* Timer interrupt has highest priority. */ |
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irq = irq_from_virq(cpu, VIRQ_TIMER); |
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if (irq != -1) { |
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evtchn_port_t evtchn = evtchn_from_irq(irq); |
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word_idx = evtchn / BITS_PER_LONG; |
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bit_idx = evtchn % BITS_PER_LONG; |
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if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx)) |
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generic_handle_irq(irq); |
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} |
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/* |
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* Master flag must be cleared /before/ clearing |
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* selector flag. xchg_xen_ulong must contain an |
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* appropriate barrier. |
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*/ |
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pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0); |
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start_word_idx = __this_cpu_read(current_word_idx); |
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start_bit_idx = __this_cpu_read(current_bit_idx); |
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word_idx = start_word_idx; |
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for (i = 0; pending_words != 0; i++) { |
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xen_ulong_t words; |
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words = MASK_LSBS(pending_words, word_idx); |
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/* |
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* If we masked out all events, wrap to beginning. |
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*/ |
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if (words == 0) { |
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word_idx = 0; |
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bit_idx = 0; |
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continue; |
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} |
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word_idx = EVTCHN_FIRST_BIT(words); |
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pending_bits = active_evtchns(cpu, s, word_idx); |
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bit_idx = 0; /* usually scan entire word from start */ |
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/* |
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* We scan the starting word in two parts. |
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* |
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* 1st time: start in the middle, scanning the |
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* upper bits. |
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* |
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* 2nd time: scan the whole word (not just the |
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* parts skipped in the first pass) -- if an |
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* event in the previously scanned bits is |
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* pending again it would just be scanned on |
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* the next loop anyway. |
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*/ |
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if (word_idx == start_word_idx) { |
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if (i == 0) |
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bit_idx = start_bit_idx; |
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} |
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do { |
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xen_ulong_t bits; |
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evtchn_port_t port; |
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bits = MASK_LSBS(pending_bits, bit_idx); |
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/* If we masked out all events, move on. */ |
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if (bits == 0) |
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break; |
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bit_idx = EVTCHN_FIRST_BIT(bits); |
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/* Process port. */ |
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port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx; |
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handle_irq_for_port(port, ctrl); |
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bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD; |
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/* Next caller starts at last processed + 1 */ |
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__this_cpu_write(current_word_idx, |
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bit_idx ? word_idx : |
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(word_idx+1) % BITS_PER_EVTCHN_WORD); |
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__this_cpu_write(current_bit_idx, bit_idx); |
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} while (bit_idx != 0); |
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/* Scan start_l1i twice; all others once. */ |
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if ((word_idx != start_word_idx) || (i != 0)) |
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pending_words &= ~(1UL << word_idx); |
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word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD; |
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} |
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} |
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irqreturn_t xen_debug_interrupt(int irq, void *dev_id) |
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{ |
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struct shared_info *sh = HYPERVISOR_shared_info; |
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int cpu = smp_processor_id(); |
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xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu); |
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int i; |
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unsigned long flags; |
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static DEFINE_SPINLOCK(debug_lock); |
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struct vcpu_info *v; |
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spin_lock_irqsave(&debug_lock, flags); |
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printk("\nvcpu %d\n ", cpu); |
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for_each_online_cpu(i) { |
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int pending; |
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v = per_cpu(xen_vcpu, i); |
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pending = (get_irq_regs() && i == cpu) |
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? xen_irqs_disabled(get_irq_regs()) |
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: v->evtchn_upcall_mask; |
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printk("%d: masked=%d pending=%d event_sel %0*"PRI_xen_ulong"\n ", i, |
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pending, v->evtchn_upcall_pending, |
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(int)(sizeof(v->evtchn_pending_sel)*2), |
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v->evtchn_pending_sel); |
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} |
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v = per_cpu(xen_vcpu, cpu); |
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printk("\npending:\n "); |
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for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--) |
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printk("%0*"PRI_xen_ulong"%s", |
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(int)sizeof(sh->evtchn_pending[0])*2, |
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sh->evtchn_pending[i], |
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i % 8 == 0 ? "\n " : " "); |
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printk("\nglobal mask:\n "); |
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for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) |
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printk("%0*"PRI_xen_ulong"%s", |
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(int)(sizeof(sh->evtchn_mask[0])*2), |
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sh->evtchn_mask[i], |
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i % 8 == 0 ? "\n " : " "); |
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printk("\nglobally unmasked:\n "); |
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for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) |
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printk("%0*"PRI_xen_ulong"%s", |
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(int)(sizeof(sh->evtchn_mask[0])*2), |
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sh->evtchn_pending[i] & ~sh->evtchn_mask[i], |
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i % 8 == 0 ? "\n " : " "); |
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printk("\nlocal cpu%d mask:\n ", cpu); |
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for (i = (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--) |
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printk("%0*"PRI_xen_ulong"%s", (int)(sizeof(cpu_evtchn[0])*2), |
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cpu_evtchn[i], |
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i % 8 == 0 ? "\n " : " "); |
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printk("\nlocally unmasked:\n "); |
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for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) { |
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xen_ulong_t pending = sh->evtchn_pending[i] |
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& ~sh->evtchn_mask[i] |
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& cpu_evtchn[i]; |
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printk("%0*"PRI_xen_ulong"%s", |
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(int)(sizeof(sh->evtchn_mask[0])*2), |
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pending, i % 8 == 0 ? "\n " : " "); |
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} |
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printk("\npending list:\n"); |
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for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) { |
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if (sync_test_bit(i, BM(sh->evtchn_pending))) { |
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int word_idx = i / BITS_PER_EVTCHN_WORD; |
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printk(" %d: event %d -> irq %d%s%s%s\n", |
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cpu_from_evtchn(i), i, |
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get_evtchn_to_irq(i), |
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sync_test_bit(word_idx, BM(&v->evtchn_pending_sel)) |
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? "" : " l2-clear", |
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!sync_test_bit(i, BM(sh->evtchn_mask)) |
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? "" : " globally-masked", |
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sync_test_bit(i, BM(cpu_evtchn)) |
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? "" : " locally-masked"); |
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} |
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} |
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spin_unlock_irqrestore(&debug_lock, flags); |
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return IRQ_HANDLED; |
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} |
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static void evtchn_2l_resume(void) |
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{ |
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int i; |
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for_each_online_cpu(i) |
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memset(per_cpu(cpu_evtchn_mask, i), 0, sizeof(xen_ulong_t) * |
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EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD); |
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} |
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static int evtchn_2l_percpu_deinit(unsigned int cpu) |
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{ |
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memset(per_cpu(cpu_evtchn_mask, cpu), 0, sizeof(xen_ulong_t) * |
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EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD); |
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return 0; |
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} |
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static const struct evtchn_ops evtchn_ops_2l = { |
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.max_channels = evtchn_2l_max_channels, |
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.nr_channels = evtchn_2l_max_channels, |
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.remove = evtchn_2l_remove, |
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.bind_to_cpu = evtchn_2l_bind_to_cpu, |
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.clear_pending = evtchn_2l_clear_pending, |
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.set_pending = evtchn_2l_set_pending, |
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.is_pending = evtchn_2l_is_pending, |
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.mask = evtchn_2l_mask, |
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.unmask = evtchn_2l_unmask, |
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.handle_events = evtchn_2l_handle_events, |
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.resume = evtchn_2l_resume, |
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.percpu_deinit = evtchn_2l_percpu_deinit, |
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}; |
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void __init xen_evtchn_2l_init(void) |
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{ |
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pr_info("Using 2-level ABI\n"); |
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evtchn_ops = &evtchn_ops_2l; |
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}
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