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1// SPDX-License-Identifier: GPL-2.02/*3 * Xen event channels (2-level ABI)4 *5 * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 20076 */7 8#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt9 10#include <linux/linkage.h>11#include <linux/interrupt.h>12#include <linux/irq.h>13 14#include <asm/sync_bitops.h>15#include <asm/xen/hypercall.h>16#include <asm/xen/hypervisor.h>17 18#include <xen/xen.h>19#include <xen/xen-ops.h>20#include <xen/events.h>21#include <xen/interface/xen.h>22#include <xen/interface/event_channel.h>23 24#include "events_internal.h"25 26/*27 * Note sizeof(xen_ulong_t) can be more than sizeof(unsigned long). Be28 * careful to only use bitops which allow for this (e.g29 * test_bit/find_first_bit and friends but not __ffs) and to pass30 * BITS_PER_EVTCHN_WORD as the bitmask length.31 */32#define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)33/*34 * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t35 * array. Primarily to avoid long lines (hence the terse name).36 */37#define BM(x) (unsigned long *)(x)38/* Find the first set bit in a evtchn mask */39#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_EVTCHN_WORD)40 41#define EVTCHN_MASK_SIZE (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)42 43static DEFINE_PER_CPU(xen_ulong_t [EVTCHN_MASK_SIZE], cpu_evtchn_mask);44 45static unsigned evtchn_2l_max_channels(void)46{47 return EVTCHN_2L_NR_CHANNELS;48}49 50static void evtchn_2l_remove(evtchn_port_t evtchn, unsigned int cpu)51{52 clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));53}54 55static void evtchn_2l_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu,56 unsigned int old_cpu)57{58 clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, old_cpu)));59 set_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));60}61 62static void evtchn_2l_clear_pending(evtchn_port_t port)63{64 struct shared_info *s = HYPERVISOR_shared_info;65 sync_clear_bit(port, BM(&s->evtchn_pending[0]));66}67 68static void evtchn_2l_set_pending(evtchn_port_t port)69{70 struct shared_info *s = HYPERVISOR_shared_info;71 sync_set_bit(port, BM(&s->evtchn_pending[0]));72}73 74static bool evtchn_2l_is_pending(evtchn_port_t port)75{76 struct shared_info *s = HYPERVISOR_shared_info;77 return sync_test_bit(port, BM(&s->evtchn_pending[0]));78}79 80static void evtchn_2l_mask(evtchn_port_t port)81{82 struct shared_info *s = HYPERVISOR_shared_info;83 sync_set_bit(port, BM(&s->evtchn_mask[0]));84}85 86static void evtchn_2l_unmask(evtchn_port_t port)87{88 struct shared_info *s = HYPERVISOR_shared_info;89 unsigned int cpu = get_cpu();90 int do_hypercall = 0, evtchn_pending = 0;91 92 BUG_ON(!irqs_disabled());93 94 smp_wmb(); /* All writes before unmask must be visible. */95 96 if (unlikely((cpu != cpu_from_evtchn(port))))97 do_hypercall = 1;98 else {99 /*100 * Need to clear the mask before checking pending to101 * avoid a race with an event becoming pending.102 *103 * EVTCHNOP_unmask will only trigger an upcall if the104 * mask bit was set, so if a hypercall is needed105 * remask the event.106 */107 sync_clear_bit(port, BM(&s->evtchn_mask[0]));108 evtchn_pending = sync_test_bit(port, BM(&s->evtchn_pending[0]));109 110 if (unlikely(evtchn_pending && xen_hvm_domain())) {111 sync_set_bit(port, BM(&s->evtchn_mask[0]));112 do_hypercall = 1;113 }114 }115 116 /* Slow path (hypercall) if this is a non-local port or if this is117 * an hvm domain and an event is pending (hvm domains don't have118 * their own implementation of irq_enable). */119 if (do_hypercall) {120 struct evtchn_unmask unmask = { .port = port };121 (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);122 } else {123 struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);124 125 /*126 * The following is basically the equivalent of127 * 'hw_resend_irq'. Just like a real IO-APIC we 'lose128 * the interrupt edge' if the channel is masked.129 */130 if (evtchn_pending &&131 !sync_test_and_set_bit(port / BITS_PER_EVTCHN_WORD,132 BM(&vcpu_info->evtchn_pending_sel)))133 vcpu_info->evtchn_upcall_pending = 1;134 }135 136 put_cpu();137}138 139static DEFINE_PER_CPU(unsigned int, current_word_idx);140static DEFINE_PER_CPU(unsigned int, current_bit_idx);141 142/*143 * Mask out the i least significant bits of w144 */145#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))146 147static inline xen_ulong_t active_evtchns(unsigned int cpu,148 struct shared_info *sh,149 unsigned int idx)150{151 return sh->evtchn_pending[idx] &152 per_cpu(cpu_evtchn_mask, cpu)[idx] &153 ~sh->evtchn_mask[idx];154}155 156/*157 * Search the CPU's pending events bitmasks. For each one found, map158 * the event number to an irq, and feed it into do_IRQ() for handling.159 *160 * Xen uses a two-level bitmap to speed searching. The first level is161 * a bitset of words which contain pending event bits. The second162 * level is a bitset of pending events themselves.163 */164static void evtchn_2l_handle_events(unsigned cpu, struct evtchn_loop_ctrl *ctrl)165{166 int irq;167 xen_ulong_t pending_words;168 xen_ulong_t pending_bits;169 int start_word_idx, start_bit_idx;170 int word_idx, bit_idx;171 int i;172 struct shared_info *s = HYPERVISOR_shared_info;173 struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);174 evtchn_port_t evtchn;175 176 /* Timer interrupt has highest priority. */177 irq = irq_evtchn_from_virq(cpu, VIRQ_TIMER, &evtchn);178 if (irq != -1) {179 word_idx = evtchn / BITS_PER_LONG;180 bit_idx = evtchn % BITS_PER_LONG;181 if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx))182 generic_handle_irq(irq);183 }184 185 /*186 * Master flag must be cleared /before/ clearing187 * selector flag. xchg_xen_ulong must contain an188 * appropriate barrier.189 */190 pending_words = xchg_xen_ulong(&vcpu_info->evtchn_pending_sel, 0);191 192 start_word_idx = __this_cpu_read(current_word_idx);193 start_bit_idx = __this_cpu_read(current_bit_idx);194 195 word_idx = start_word_idx;196 197 for (i = 0; pending_words != 0; i++) {198 xen_ulong_t words;199 200 words = MASK_LSBS(pending_words, word_idx);201 202 /*203 * If we masked out all events, wrap to beginning.204 */205 if (words == 0) {206 word_idx = 0;207 bit_idx = 0;208 continue;209 }210 word_idx = EVTCHN_FIRST_BIT(words);211 212 pending_bits = active_evtchns(cpu, s, word_idx);213 bit_idx = 0; /* usually scan entire word from start */214 /*215 * We scan the starting word in two parts.216 *217 * 1st time: start in the middle, scanning the218 * upper bits.219 *220 * 2nd time: scan the whole word (not just the221 * parts skipped in the first pass) -- if an222 * event in the previously scanned bits is223 * pending again it would just be scanned on224 * the next loop anyway.225 */226 if (word_idx == start_word_idx) {227 if (i == 0)228 bit_idx = start_bit_idx;229 }230 231 do {232 xen_ulong_t bits;233 evtchn_port_t port;234 235 bits = MASK_LSBS(pending_bits, bit_idx);236 237 /* If we masked out all events, move on. */238 if (bits == 0)239 break;240 241 bit_idx = EVTCHN_FIRST_BIT(bits);242 243 /* Process port. */244 port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx;245 handle_irq_for_port(port, ctrl);246 247 bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD;248 249 /* Next caller starts at last processed + 1 */250 __this_cpu_write(current_word_idx,251 bit_idx ? word_idx :252 (word_idx+1) % BITS_PER_EVTCHN_WORD);253 __this_cpu_write(current_bit_idx, bit_idx);254 } while (bit_idx != 0);255 256 /* Scan start_l1i twice; all others once. */257 if ((word_idx != start_word_idx) || (i != 0))258 pending_words &= ~(1UL << word_idx);259 260 word_idx = (word_idx + 1) % BITS_PER_EVTCHN_WORD;261 }262}263 264irqreturn_t xen_debug_interrupt(int irq, void *dev_id)265{266 struct shared_info *sh = HYPERVISOR_shared_info;267 int cpu = smp_processor_id();268 xen_ulong_t *cpu_evtchn = per_cpu(cpu_evtchn_mask, cpu);269 int i;270 unsigned long flags;271 static DEFINE_SPINLOCK(debug_lock);272 struct vcpu_info *v;273 274 spin_lock_irqsave(&debug_lock, flags);275 276 printk("\nvcpu %d\n ", cpu);277 278 for_each_online_cpu(i) {279 int pending;280 v = per_cpu(xen_vcpu, i);281 pending = (get_irq_regs() && i == cpu)282 ? xen_irqs_disabled(get_irq_regs())283 : v->evtchn_upcall_mask;284 printk("%d: masked=%d pending=%d event_sel %0*"PRI_xen_ulong"\n ", i,285 pending, v->evtchn_upcall_pending,286 (int)(sizeof(v->evtchn_pending_sel)*2),287 v->evtchn_pending_sel);288 }289 v = per_cpu(xen_vcpu, cpu);290 291 printk("\npending:\n ");292 for (i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--)293 printk("%0*"PRI_xen_ulong"%s",294 (int)sizeof(sh->evtchn_pending[0])*2,295 sh->evtchn_pending[i],296 i % 8 == 0 ? "\n " : " ");297 printk("\nglobal mask:\n ");298 for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)299 printk("%0*"PRI_xen_ulong"%s",300 (int)(sizeof(sh->evtchn_mask[0])*2),301 sh->evtchn_mask[i],302 i % 8 == 0 ? "\n " : " ");303 304 printk("\nglobally unmasked:\n ");305 for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--)306 printk("%0*"PRI_xen_ulong"%s",307 (int)(sizeof(sh->evtchn_mask[0])*2),308 sh->evtchn_pending[i] & ~sh->evtchn_mask[i],309 i % 8 == 0 ? "\n " : " ");310 311 printk("\nlocal cpu%d mask:\n ", cpu);312 for (i = (EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD)-1; i >= 0; i--)313 printk("%0*"PRI_xen_ulong"%s", (int)(sizeof(cpu_evtchn[0])*2),314 cpu_evtchn[i],315 i % 8 == 0 ? "\n " : " ");316 317 printk("\nlocally unmasked:\n ");318 for (i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) {319 xen_ulong_t pending = sh->evtchn_pending[i]320 & ~sh->evtchn_mask[i]321 & cpu_evtchn[i];322 printk("%0*"PRI_xen_ulong"%s",323 (int)(sizeof(sh->evtchn_mask[0])*2),324 pending, i % 8 == 0 ? "\n " : " ");325 }326 327 printk("\npending list:\n");328 for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) {329 if (sync_test_bit(i, BM(sh->evtchn_pending))) {330 int word_idx = i / BITS_PER_EVTCHN_WORD;331 printk(" %d: event %d -> irq %u%s%s%s\n",332 cpu_from_evtchn(i), i,333 irq_from_evtchn(i),334 sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))335 ? "" : " l2-clear",336 !sync_test_bit(i, BM(sh->evtchn_mask))337 ? "" : " globally-masked",338 sync_test_bit(i, BM(cpu_evtchn))339 ? "" : " locally-masked");340 }341 }342 343 spin_unlock_irqrestore(&debug_lock, flags);344 345 return IRQ_HANDLED;346}347 348static void evtchn_2l_resume(void)349{350 int i;351 352 for_each_online_cpu(i)353 memset(per_cpu(cpu_evtchn_mask, i), 0, sizeof(xen_ulong_t) *354 EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD);355}356 357static int evtchn_2l_percpu_deinit(unsigned int cpu)358{359 memset(per_cpu(cpu_evtchn_mask, cpu), 0, sizeof(xen_ulong_t) *360 EVTCHN_2L_NR_CHANNELS/BITS_PER_EVTCHN_WORD);361 362 return 0;363}364 365static const struct evtchn_ops evtchn_ops_2l = {366 .max_channels = evtchn_2l_max_channels,367 .nr_channels = evtchn_2l_max_channels,368 .remove = evtchn_2l_remove,369 .bind_to_cpu = evtchn_2l_bind_to_cpu,370 .clear_pending = evtchn_2l_clear_pending,371 .set_pending = evtchn_2l_set_pending,372 .is_pending = evtchn_2l_is_pending,373 .mask = evtchn_2l_mask,374 .unmask = evtchn_2l_unmask,375 .handle_events = evtchn_2l_handle_events,376 .resume = evtchn_2l_resume,377 .percpu_deinit = evtchn_2l_percpu_deinit,378};379 380void __init xen_evtchn_2l_init(void)381{382 pr_info("Using 2-level ABI\n");383 evtchn_ops = &evtchn_ops_2l;384}385