From 4b69c7e265a2c2fd1120c431c5d8d0809d4ec10a Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 17 Jun 2014 23:10:26 +0100 Subject: target-mips: Reset CPU timer consistently The MIPS CPU timer (CP0 Count/Compare registers & QEMU timer) is reset at machine initialisation, including starting the timeout. Both registers however are placed before mvp in CPUMIPSState so they will both be zeroed on reset by the memset in mips_cpu_reset() including soon after init. This doesn't take into account that the timer may be running, in which case env->CP0_Count will represent the delta against the VM clock and the timeout will need updating. At init time (cpu_mips_clock_init()), lets only create the timer. Setting Count = 1 and starting the timer (cpu_mips_store_count()) can be done at reset time from cpu_state_reset(), which is after the memset. There is also no need to set CP0_Compare = 0 as that is already handled by the memset. Note that a reset occurs from mips_cpu_realizefn() which is before the machine init callback has had a chance to set up the CPU interrupts and the CPU timer, so env->timer will be NULL. This case is handled explicitly in cpu_mips_store_count(), treating the timer as disabled (which will also be the right thing to do when KVM support is added). Reported-by: Paolo Bonzini Signed-off-by: James Hogan Cc: Aurelien Jarno Signed-off-by: Paolo Bonzini --- hw/mips/cputimer.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'hw/mips') diff --git a/hw/mips/cputimer.c b/hw/mips/cputimer.c index c8b4b000cd..6900a745c6 100644 --- a/hw/mips/cputimer.c +++ b/hw/mips/cputimer.c @@ -85,7 +85,12 @@ uint32_t cpu_mips_get_count (CPUMIPSState *env) void cpu_mips_store_count (CPUMIPSState *env, uint32_t count) { - if (env->CP0_Cause & (1 << CP0Ca_DC)) + /* + * This gets called from cpu_state_reset(), potentially before timer init. + * So env->timer may be NULL, which is also the case with KVM enabled so + * treat timer as disabled in that case. + */ + if (env->CP0_Cause & (1 << CP0Ca_DC) || !env->timer) env->CP0_Count = count; else { /* Store new count register */ @@ -142,6 +147,4 @@ static void mips_timer_cb (void *opaque) void cpu_mips_clock_init (CPUMIPSState *env) { env->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &mips_timer_cb, env); - env->CP0_Compare = 0; - cpu_mips_store_count(env, 1); } -- cgit v1.2.3