On Wed, Dec 26, 2012 at 10:39:54PM -0700, Matthew Ogilvie wrote: > 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)); I do not understand what are you trying to do here. You assume that trigger will happen 2 clocks after counter is loaded? > + } > 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 -- Gleb. -- 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
