Make git_get_out() consistent with spec. Currently pit_get_out() doesn't affect IRQ0, but it can be read by the guest in other ways. This makes it consistent with proposed changes in qemu's i8254 model as well. See http://bochs.sourceforge.net/techspec/intel-82c54-timer.pdf.gz or search the net for 23124406.pdf. Signed-off-by: Matthew Ogilvie <mmogilvi_qemu@xxxxxxxxxxxx> --- arch/x86/kvm/i8254.c | 44 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 34 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index cd4ec60..fd38938 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -144,6 +144,10 @@ static int pit_get_count(struct kvm *kvm, int channel) WARN_ON(!mutex_is_locked(&kvm->arch.vpit->pit_state.lock)); + /* FIXME: Add some way to represent a paused timer and return + * the paused-at counter value, to better model gate pausing, + * "wait until next CLK pulse to load counter" logic, etc. + */ t = kpit_elapsed(kvm, c, channel); d = muldiv64(t, KVM_PIT_FREQ, NSEC_PER_SEC); @@ -155,8 +159,7 @@ static int pit_get_count(struct kvm *kvm, int channel) counter = (c->count - d) & 0xffff; break; case 3: - /* XXX: may be incorrect for odd counts */ - counter = c->count - (mod_64((2 * d), c->count)); + counter = (c->count - (mod_64((2 * d), c->count))) & 0xfffe; break; default: counter = c->count - mod_64(d, c->count); @@ -180,20 +183,18 @@ static int pit_get_out(struct kvm *kvm, int channel) switch (c->mode) { default: case 0: - out = (d >= c->count); - break; case 1: - out = (d < c->count); + out = (d >= c->count); break; case 2: - out = ((mod_64(d, c->count) == 0) && (d != 0)); + out = (mod_64(d, c->count) != (c->count - 1) || c->gate == 0); break; case 3: - out = (mod_64(d, c->count) < ((c->count + 1) >> 1)); + out = (mod_64(d, c->count) < ((c->count + 1) >> 1) || c->gate == 0); break; case 4: case 5: - out = (d == c->count); + out = (d != c->count); break; } @@ -367,7 +368,7 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) /* * The largest possible initial count is 0; this is equivalent - * to 216 for binary counting and 104 for BCD counting. + * to pow(2,16) for binary counting and pow(10,4) for BCD counting. */ if (val == 0) val = 0x10000; @@ -376,6 +377,26 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) if (channel != 0) { ps->channels[channel].count_load_time = ktime_get(); + + /* In gate-triggered one-shot modes, + * indirectly model some pit_get_out() + * cases by setting the load time way + * back until gate-triggered. + * (Generally only affects reading status + * from channel 2 speaker, + * due to hard-wired gates on other + * channels.) + * + * FIXME: This might be redesigned if a paused + * timer state is added for pit_get_count(). + */ + if (ps->channels[channel].mode == 1 || + ps->channels[channel].mode == 5) { + u64 delta = muldiv64(val+2, NSEC_PER_SEC, KVM_PIT_FREQ); + ps->channels[channel].count_load_time = + ktime_sub(ps->channels[channel].count_load_time, + ns_to_ktime(delta)); + } return; } @@ -383,7 +404,6 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) * mode 1 is one shot, mode 2 is period, otherwise del timer */ switch (ps->channels[0].mode) { case 0: - case 1: /* FIXME: enhance mode 4 precision */ case 4: create_pit_timer(kvm, val, 0); @@ -393,6 +413,10 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) create_pit_timer(kvm, val, 1); break; default: + /* Modes 1 and 5 are triggered by gate leading edge, + * but channel 0's gate is hard-wired high and has + * no edges (on normal real hardware). + */ destroy_pit_timer(kvm->arch.vpit); } } -- 1.7.10.2.484.gcd07cc5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
