/* $OpenBSD: i8253.c,v 1.36 2022/11/10 18:58:02 mbuhl Exp $ */ /* * Copyright (c) 2016 Mike Larkin * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include #include #include #include #include #include #include "i8253.h" #include "vmd.h" #include "vmm.h" #include "atomicio.h" extern char *__progname; /* * Channel 0 is used to generate the legacy hardclock interrupt (HZ). * Channels 1 and 2 can be used by the guest OS as regular timers, * but channel 2 is not connected to any pcppi(4)-like device. Like * a regular PC, channel 2 status can also be read from port 0x61. */ struct i8253_channel i8253_channel[3]; static struct vm_dev_pipe dev_pipe; /* * i8253_pipe_dispatch * * Reads a message off the pipe, expecting one that corresponds to a * reset request for a specific channel. */ static void i8253_pipe_dispatch(int fd, short event, void *arg) { enum pipe_msg_type msg; msg = vm_pipe_recv(&dev_pipe); switch (msg) { case I8253_RESET_CHAN_0: i8253_reset(0); break; case I8253_RESET_CHAN_1: i8253_reset(1); break; case I8253_RESET_CHAN_2: i8253_reset(2); break; default: fatalx("%s: unexpected pipe message %d", __func__, msg); } } /* * i8253_init * * Initialize the emulated i8253 PIT. * * Parameters: * vm_id: vmm(4)-assigned ID of the VM */ void i8253_init(uint32_t vm_id) { memset(&i8253_channel, 0, sizeof(struct i8253_channel)); clock_gettime(CLOCK_MONOTONIC, &i8253_channel[0].ts); i8253_channel[0].start = 0xFFFF; i8253_channel[0].mode = TIMER_INTTC; i8253_channel[0].last_r = 1; i8253_channel[0].vm_id = vm_id; i8253_channel[0].state = 0; i8253_channel[1].start = 0xFFFF; i8253_channel[1].mode = TIMER_INTTC; i8253_channel[1].last_r = 1; i8253_channel[1].vm_id = vm_id; i8253_channel[1].state = 0; i8253_channel[2].start = 0xFFFF; i8253_channel[2].mode = TIMER_INTTC; i8253_channel[2].last_r = 1; i8253_channel[2].vm_id = vm_id; i8253_channel[2].state = 0; evtimer_set(&i8253_channel[0].timer, i8253_fire, &i8253_channel[0]); evtimer_set(&i8253_channel[1].timer, i8253_fire, &i8253_channel[1]); evtimer_set(&i8253_channel[2].timer, i8253_fire, &i8253_channel[2]); vm_pipe_init(&dev_pipe, i8253_pipe_dispatch); event_add(&dev_pipe.read_ev, NULL); } /* * i8253_do_readback * * Handles the readback status command. The readback status command latches * the current counter value plus various status bits. * * Parameters: * data: The command word written by the guest VM */ void i8253_do_readback(uint32_t data) { struct timespec now, delta; uint64_t ns, ticks; int readback_channel[3] = { TIMER_RB_C0, TIMER_RB_C1, TIMER_RB_C2 }; int i; /* bits are inverted here - !TIMER_RB_STATUS == enable chan readback */ if (data & ~TIMER_RB_STATUS) { i8253_channel[0].rbs = (data & TIMER_RB_C0) ? 1 : 0; i8253_channel[1].rbs = (data & TIMER_RB_C1) ? 1 : 0; i8253_channel[2].rbs = (data & TIMER_RB_C2) ? 1 : 0; } /* !TIMER_RB_COUNT == enable counter readback */ if (data & ~TIMER_RB_COUNT) { clock_gettime(CLOCK_MONOTONIC, &now); for (i = 0; i < 3; i++) { if (data & readback_channel[i]) { timespecsub(&now, &i8253_channel[i].ts, &delta); ns = delta.tv_sec * 1000000000 + delta.tv_nsec; ticks = ns / NS_PER_TICK; if (i8253_channel[i].start) i8253_channel[i].olatch = i8253_channel[i].start - ticks % i8253_channel[i].start; else i8253_channel[i].olatch = 0; } } } } /* * vcpu_exit_i8253_misc * * Handles the 0x61 misc i8253 PIT register in/out exits. * * Parameters: * vrp: vm run parameters containing exit information for the I/O * instruction being performed * * Return value: * Always 0xFF (no interrupt should be injected) */ uint8_t vcpu_exit_i8253_misc(struct vm_run_params *vrp) { struct vm_exit *vei = vrp->vrp_exit; uint16_t cur; uint64_t ns, ticks; struct timespec now, delta; if (vei->vei.vei_dir == VEI_DIR_IN) { /* Port 0x61[5] = counter channel 2 state */ if (i8253_channel[2].mode == TIMER_INTTC) { if (i8253_channel[2].state) { set_return_data(vei, (1 << 5)); log_debug("%s: counter 2 fired, returning " "0x20", __func__); } else { set_return_data(vei, 0); log_debug("%s: counter 2 clear, returning 0x0", __func__); } } else if (i8253_channel[2].mode == TIMER_SQWAVE) { clock_gettime(CLOCK_MONOTONIC, &now); timespecsub(&now, &i8253_channel[2].ts, &delta); ns = delta.tv_sec * 1000000000 + delta.tv_nsec; ticks = ns / NS_PER_TICK; if (i8253_channel[2].start) { cur = i8253_channel[2].start - ticks % i8253_channel[2].start; if (cur > i8253_channel[2].start / 2) set_return_data(vei, 1); else set_return_data(vei, 0); } } } else { log_debug("%s: discarding data written to PIT misc port", __func__); } return 0xFF; } /* * vcpu_exit_i8253 * * Handles emulated i8253 PIT access (in/out instruction to PIT ports). * * Parameters: * vrp: vm run parameters containing exit information for the I/O * instruction being performed * * Return value: * Interrupt to inject to the guest VM, or 0xFF if no interrupt should * be injected. */ uint8_t vcpu_exit_i8253(struct vm_run_params *vrp) { uint32_t out_data = 0; uint8_t sel, rw, data; uint64_t ns, ticks; struct timespec now, delta; struct vm_exit *vei = vrp->vrp_exit; get_input_data(vei, &out_data); if (vei->vei.vei_port == TIMER_CTRL) { if (vei->vei.vei_dir == VEI_DIR_OUT) { /* OUT instruction */ sel = out_data & (TIMER_SEL0 | TIMER_SEL1 | TIMER_SEL2); sel = sel >> 6; if (sel == 3) { i8253_do_readback(out_data); return (0xFF); } rw = out_data & (TIMER_LATCH | TIMER_16BIT); /* * Since we don't truly emulate each tick of the PIT * counter, when the guest asks for the timer to be * latched, simulate what the counter would have been * had we performed full emulation. We do this by * calculating when the counter was reset vs how much * time has elapsed, then bias by the counter tick * rate. */ if (rw == TIMER_LATCH) { clock_gettime(CLOCK_MONOTONIC, &now); timespecsub(&now, &i8253_channel[sel].ts, &delta); ns = delta.tv_sec * 1000000000 + delta.tv_nsec; ticks = ns / NS_PER_TICK; if (i8253_channel[sel].start) { i8253_channel[sel].olatch = i8253_channel[sel].start - ticks % i8253_channel[sel].start; } else i8253_channel[sel].olatch = 0; goto ret; } else if (rw != TIMER_16BIT) { log_warnx("%s: i8253 PIT: unsupported counter " "%d rw mode 0x%x selected", __func__, sel, (rw & TIMER_16BIT)); } i8253_channel[sel].mode = (out_data & 0xe) >> 1; goto ret; } else { log_warnx("%s: i8253 PIT: read from control port " "unsupported", __progname); set_return_data(vei, 0); } } else { sel = vei->vei.vei_port - (TIMER_CNTR0 + TIMER_BASE); if (vei->vei.vei_dir == VEI_DIR_OUT) { /* OUT instruction */ if (i8253_channel[sel].last_w == 0) { i8253_channel[sel].ilatch |= (out_data & 0xff); i8253_channel[sel].last_w = 1; } else { i8253_channel[sel].ilatch |= ((out_data & 0xff) << 8); i8253_channel[sel].start = i8253_channel[sel].ilatch; i8253_channel[sel].last_w = 0; if (i8253_channel[sel].start == 0) i8253_channel[sel].start = 0xffff; log_debug("%s: channel %d reset, mode=%d, " "start=%d", __func__, sel, i8253_channel[sel].mode, i8253_channel[sel].start); vm_pipe_send(&dev_pipe, sel); } } else { if (i8253_channel[sel].rbs) { i8253_channel[sel].rbs = 0; data = i8253_channel[sel].mode << 1; data |= TIMER_16BIT; set_return_data(vei, data); goto ret; } if (i8253_channel[sel].last_r == 0) { data = i8253_channel[sel].olatch >> 8; set_return_data(vei, data); i8253_channel[sel].last_r = 1; } else { data = i8253_channel[sel].olatch & 0xFF; set_return_data(vei, data); i8253_channel[sel].last_r = 0; } } } ret: return (0xFF); } /* * i8253_reset * * Resets the i8253's counter timer * * Parameters: * chn: counter ID. Only channel ID 0 is presently emulated. */ void i8253_reset(uint8_t chn) { struct timeval tv; evtimer_del(&i8253_channel[chn].timer); timerclear(&tv); i8253_channel[chn].in_use = 1; i8253_channel[chn].state = 0; tv.tv_usec = (i8253_channel[chn].start * NS_PER_TICK) / 1000; clock_gettime(CLOCK_MONOTONIC, &i8253_channel[chn].ts); evtimer_add(&i8253_channel[chn].timer, &tv); } /* * i8253_fire * * Callback invoked when the 8253 PIT timer fires. This will assert * IRQ0 on the legacy PIC attached to VCPU0. * * Parameters: * fd: unused * type: unused * arg: VM ID */ void i8253_fire(int fd, short type, void *arg) { struct timeval tv; struct i8253_channel *ctr = (struct i8253_channel *)arg; vcpu_assert_pic_irq(ctr->vm_id, 0, 0); vcpu_deassert_pic_irq(ctr->vm_id, 0, 0); if (ctr->mode != TIMER_INTTC) { timerclear(&tv); tv.tv_usec = (ctr->start * NS_PER_TICK) / 1000; evtimer_add(&ctr->timer, &tv); } else ctr->state = 1; } int i8253_dump(int fd) { log_debug("%s: sending PIT", __func__); if (atomicio(vwrite, fd, &i8253_channel, sizeof(i8253_channel)) != sizeof(i8253_channel)) { log_warnx("%s: error writing PIT to fd", __func__); return (-1); } return (0); } int i8253_restore(int fd, uint32_t vm_id) { int i; log_debug("%s: restoring PIT", __func__); if (atomicio(read, fd, &i8253_channel, sizeof(i8253_channel)) != sizeof(i8253_channel)) { log_warnx("%s: error reading PIT from fd", __func__); return (-1); } for (i = 0; i < 3; i++) { memset(&i8253_channel[i].timer, 0, sizeof(struct event)); i8253_channel[i].vm_id = vm_id; evtimer_set(&i8253_channel[i].timer, i8253_fire, &i8253_channel[i]); i8253_reset(i); } vm_pipe_init(&dev_pipe, i8253_pipe_dispatch); return (0); } void i8253_stop() { int i; for (i = 0; i < 3; i++) evtimer_del(&i8253_channel[i].timer); event_del(&dev_pipe.read_ev); } void i8253_start() { int i; for (i = 0; i < 3; i++) if (i8253_channel[i].in_use) i8253_reset(i); event_add(&dev_pipe.read_ev, NULL); }