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qemu-e2k/hw/ppc/ppc_booke.c
Roman Kapl 0dfe952dc5 ppc: Prevent inifnite loop in decrementer auto-reload. 
If the DECAR register is set to 0, QEMU tries to reload the decrementer with
zero in an inifinite loop. According to PPC documentation, the decrementer is
triggered on 1->0 transition, so avoid reloading the decrementer if if is
already zero.

The problem does not manifest under Linux, but it is valid to set DECAR to zero
(and may make sense as part of decrementer initialization when interrupts are
disabled).

Signed-off-by: Roman Kapl <rka@sysgo.com>
[dwg: Fixed style nit]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2017-01-31 10:10:14 +11:00

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/*
* QEMU PowerPC Booke hardware System Emulator
*
* Copyright (c) 2011 AdaCore
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "cpu.h"
#include "hw/hw.h"
#include "hw/ppc/ppc.h"
#include "qemu/timer.h"
#include "sysemu/sysemu.h"
#include "hw/timer/m48t59.h"
#include "qemu/log.h"
#include "hw/loader.h"
#include "kvm_ppc.h"
/* Timer Control Register */
#define TCR_WP_SHIFT 30 /* Watchdog Timer Period */
#define TCR_WP_MASK (0x3U << TCR_WP_SHIFT)
#define TCR_WRC_SHIFT 28 /* Watchdog Timer Reset Control */
#define TCR_WRC_MASK (0x3U << TCR_WRC_SHIFT)
#define TCR_WIE (1U << 27) /* Watchdog Timer Interrupt Enable */
#define TCR_DIE (1U << 26) /* Decrementer Interrupt Enable */
#define TCR_FP_SHIFT 24 /* Fixed-Interval Timer Period */
#define TCR_FP_MASK (0x3U << TCR_FP_SHIFT)
#define TCR_FIE (1U << 23) /* Fixed-Interval Timer Interrupt Enable */
#define TCR_ARE (1U << 22) /* Auto-Reload Enable */
/* Timer Control Register (e500 specific fields) */
#define TCR_E500_FPEXT_SHIFT 13 /* Fixed-Interval Timer Period Extension */
#define TCR_E500_FPEXT_MASK (0xf << TCR_E500_FPEXT_SHIFT)
#define TCR_E500_WPEXT_SHIFT 17 /* Watchdog Timer Period Extension */
#define TCR_E500_WPEXT_MASK (0xf << TCR_E500_WPEXT_SHIFT)
/* Timer Status Register */
#define TSR_FIS (1U << 26) /* Fixed-Interval Timer Interrupt Status */
#define TSR_DIS (1U << 27) /* Decrementer Interrupt Status */
#define TSR_WRS_SHIFT 28 /* Watchdog Timer Reset Status */
#define TSR_WRS_MASK (0x3U << TSR_WRS_SHIFT)
#define TSR_WIS (1U << 30) /* Watchdog Timer Interrupt Status */
#define TSR_ENW (1U << 31) /* Enable Next Watchdog Timer */
typedef struct booke_timer_t booke_timer_t;
struct booke_timer_t {
uint64_t fit_next;
QEMUTimer *fit_timer;
uint64_t wdt_next;
QEMUTimer *wdt_timer;
uint32_t flags;
};
static void booke_update_irq(PowerPCCPU *cpu)
{
CPUPPCState *env = &cpu->env;
ppc_set_irq(cpu, PPC_INTERRUPT_DECR,
(env->spr[SPR_BOOKE_TSR] & TSR_DIS
&& env->spr[SPR_BOOKE_TCR] & TCR_DIE));
ppc_set_irq(cpu, PPC_INTERRUPT_WDT,
(env->spr[SPR_BOOKE_TSR] & TSR_WIS
&& env->spr[SPR_BOOKE_TCR] & TCR_WIE));
ppc_set_irq(cpu, PPC_INTERRUPT_FIT,
(env->spr[SPR_BOOKE_TSR] & TSR_FIS
&& env->spr[SPR_BOOKE_TCR] & TCR_FIE));
}
/* Return the location of the bit of time base at which the FIT will raise an
interrupt */
static uint8_t booke_get_fit_target(CPUPPCState *env, ppc_tb_t *tb_env)
{
uint8_t fp = (env->spr[SPR_BOOKE_TCR] & TCR_FP_MASK) >> TCR_FP_SHIFT;
if (tb_env->flags & PPC_TIMER_E500) {
/* e500 Fixed-interval timer period extension */
uint32_t fpext = (env->spr[SPR_BOOKE_TCR] & TCR_E500_FPEXT_MASK)
>> TCR_E500_FPEXT_SHIFT;
fp = 63 - (fp | fpext << 2);
} else {
fp = env->fit_period[fp];
}
return fp;
}
/* Return the location of the bit of time base at which the WDT will raise an
interrupt */
static uint8_t booke_get_wdt_target(CPUPPCState *env, ppc_tb_t *tb_env)
{
uint8_t wp = (env->spr[SPR_BOOKE_TCR] & TCR_WP_MASK) >> TCR_WP_SHIFT;
if (tb_env->flags & PPC_TIMER_E500) {
/* e500 Watchdog timer period extension */
uint32_t wpext = (env->spr[SPR_BOOKE_TCR] & TCR_E500_WPEXT_MASK)
>> TCR_E500_WPEXT_SHIFT;
wp = 63 - (wp | wpext << 2);
} else {
wp = env->wdt_period[wp];
}
return wp;
}
static void booke_update_fixed_timer(CPUPPCState *env,
uint8_t target_bit,
uint64_t *next,
QEMUTimer *timer,
int tsr_bit)
{
ppc_tb_t *tb_env = env->tb_env;
uint64_t delta_tick, ticks = 0;
uint64_t tb;
uint64_t period;
uint64_t now;
if (!(env->spr[SPR_BOOKE_TSR] & tsr_bit)) {
/*
* Don't arm the timer again when the guest has the current
* interrupt still pending. Wait for it to ack it.
*/
return;
}
now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
tb = cpu_ppc_get_tb(tb_env, now, tb_env->tb_offset);
period = 1ULL << target_bit;
delta_tick = period - (tb & (period - 1));
/* the timer triggers only when the selected bit toggles from 0 to 1 */
if (tb & period) {
ticks = period;
}
if (ticks + delta_tick < ticks) {
/* Overflow, so assume the biggest number we can express. */
ticks = UINT64_MAX;
} else {
ticks += delta_tick;
}
*next = now + muldiv64(ticks, NANOSECONDS_PER_SECOND, tb_env->tb_freq);
if ((*next < now) || (*next > INT64_MAX)) {
/* Overflow, so assume the biggest number the qemu timer supports. */
*next = INT64_MAX;
}
/* XXX: If expire time is now. We can't run the callback because we don't
* have access to it. So we just set the timer one nanosecond later.
*/
if (*next == now) {
(*next)++;
} else {
/*
* There's no point to fake any granularity that's more fine grained
* than milliseconds. Anything beyond that just overloads the system.
*/
*next = MAX(*next, now + SCALE_MS);
}
/* Fire the next timer */
timer_mod(timer, *next);
}
static void booke_decr_cb(void *opaque)
{
PowerPCCPU *cpu = opaque;
CPUPPCState *env = &cpu->env;
env->spr[SPR_BOOKE_TSR] |= TSR_DIS;
booke_update_irq(cpu);
if (env->spr[SPR_BOOKE_TCR] & TCR_ARE) {
/* Do not reload 0, it is already there. It would just trigger
* the timer again and lead to infinite loop */
if (env->spr[SPR_BOOKE_DECAR] != 0) {
/* Auto Reload */
cpu_ppc_store_decr(env, env->spr[SPR_BOOKE_DECAR]);
}
}
}
static void booke_fit_cb(void *opaque)
{
PowerPCCPU *cpu = opaque;
CPUPPCState *env = &cpu->env;
ppc_tb_t *tb_env;
booke_timer_t *booke_timer;
tb_env = env->tb_env;
booke_timer = tb_env->opaque;
env->spr[SPR_BOOKE_TSR] |= TSR_FIS;
booke_update_irq(cpu);
booke_update_fixed_timer(env,
booke_get_fit_target(env, tb_env),
&booke_timer->fit_next,
booke_timer->fit_timer,
TSR_FIS);
}
static void booke_wdt_cb(void *opaque)
{
PowerPCCPU *cpu = opaque;
CPUPPCState *env = &cpu->env;
ppc_tb_t *tb_env;
booke_timer_t *booke_timer;
tb_env = env->tb_env;
booke_timer = tb_env->opaque;
/* TODO: There's lots of complicated stuff to do here */
booke_update_irq(cpu);
booke_update_fixed_timer(env,
booke_get_wdt_target(env, tb_env),
&booke_timer->wdt_next,
booke_timer->wdt_timer,
TSR_WIS);
}
void store_booke_tsr(CPUPPCState *env, target_ulong val)
{
PowerPCCPU *cpu = ppc_env_get_cpu(env);
ppc_tb_t *tb_env = env->tb_env;
booke_timer_t *booke_timer = tb_env->opaque;
env->spr[SPR_BOOKE_TSR] &= ~val;
kvmppc_clear_tsr_bits(cpu, val);
if (val & TSR_FIS) {
booke_update_fixed_timer(env,
booke_get_fit_target(env, tb_env),
&booke_timer->fit_next,
booke_timer->fit_timer,
TSR_FIS);
}
if (val & TSR_WIS) {
booke_update_fixed_timer(env,
booke_get_wdt_target(env, tb_env),
&booke_timer->wdt_next,
booke_timer->wdt_timer,
TSR_WIS);
}
booke_update_irq(cpu);
}
void store_booke_tcr(CPUPPCState *env, target_ulong val)
{
PowerPCCPU *cpu = ppc_env_get_cpu(env);
ppc_tb_t *tb_env = env->tb_env;
booke_timer_t *booke_timer = tb_env->opaque;
tb_env = env->tb_env;
env->spr[SPR_BOOKE_TCR] = val;
kvmppc_set_tcr(cpu);
booke_update_irq(cpu);
booke_update_fixed_timer(env,
booke_get_fit_target(env, tb_env),
&booke_timer->fit_next,
booke_timer->fit_timer,
TSR_FIS);
booke_update_fixed_timer(env,
booke_get_wdt_target(env, tb_env),
&booke_timer->wdt_next,
booke_timer->wdt_timer,
TSR_WIS);
}
static void ppc_booke_timer_reset_handle(void *opaque)
{
PowerPCCPU *cpu = opaque;
CPUPPCState *env = &cpu->env;
store_booke_tcr(env, 0);
store_booke_tsr(env, -1);
}
/*
* This function will be called whenever the CPU state changes.
* CPU states are defined "typedef enum RunState".
* Regarding timer, When CPU state changes to running after debug halt
* or similar cases which takes time then in between final watchdog
* expiry happenes. This will cause exit to QEMU and configured watchdog
* action will be taken. To avoid this we always clear the watchdog state when
* state changes to running.
*/
static void cpu_state_change_handler(void *opaque, int running, RunState state)
{
PowerPCCPU *cpu = opaque;
CPUPPCState *env = &cpu->env;
if (!running) {
return;
}
/*
* Clear watchdog interrupt condition by clearing TSR.
*/
store_booke_tsr(env, TSR_ENW | TSR_WIS | TSR_WRS_MASK);
}
void ppc_booke_timers_init(PowerPCCPU *cpu, uint32_t freq, uint32_t flags)
{
ppc_tb_t *tb_env;
booke_timer_t *booke_timer;
int ret = 0;
tb_env = g_malloc0(sizeof(ppc_tb_t));
booke_timer = g_malloc0(sizeof(booke_timer_t));
cpu->env.tb_env = tb_env;
tb_env->flags = flags | PPC_TIMER_BOOKE | PPC_DECR_ZERO_TRIGGERED;
tb_env->tb_freq = freq;
tb_env->decr_freq = freq;
tb_env->opaque = booke_timer;
tb_env->decr_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &booke_decr_cb, cpu);
booke_timer->fit_timer =
timer_new_ns(QEMU_CLOCK_VIRTUAL, &booke_fit_cb, cpu);
booke_timer->wdt_timer =
timer_new_ns(QEMU_CLOCK_VIRTUAL, &booke_wdt_cb, cpu);
ret = kvmppc_booke_watchdog_enable(cpu);
if (ret) {
/* TODO: Start the QEMU emulated watchdog if not running on KVM.
* Also start the QEMU emulated watchdog if KVM does not support
* emulated watchdog or somehow it is not enabled (supported but
* not enabled is though some bug and requires debugging :)).
*/
}
qemu_add_vm_change_state_handler(cpu_state_change_handler, cpu);
qemu_register_reset(ppc_booke_timer_reset_handle, cpu);
}
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