kvm: x86: only channel 0 of the i8254 is linked to the HPET

commit e5e57e7a03b1cdcb98e4aed135def2a08cbf3257 upstream.

While setting the KVM PIT counters in 'kvm_pit_load_count', if
'hpet_legacy_start' is set, the function disables the timer on
channel[0], instead of the respective index 'channel'. This is
because channels 1-3 are not linked to the HPET.  Fix the caller
to only activate the special HPET processing for channel 0.

Reported-by: P J P <pjp@fedoraproject.org>
Fixes: 0185604c2d82c560dab2f2933a18f797e74ab5a8
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 1406ffde3e35c096fba6f9ac33c155e2a7322af1..f2006e65a2383ba890ab446dca4e72652320c422 100644 (file)
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -418,6 +418,7 @@ void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_s
        u8 saved_mode;
        if (hpet_legacy_start) {
                /* save existing mode for later reenablement */
+               WARN_ON(channel != 0);
                saved_mode = kvm->arch.vpit->pit_state.channels[0].mode;
                kvm->arch.vpit->pit_state.channels[0].mode = 0xff; /* disable timer */
                pit_load_count(kvm, channel, val);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e336615e0aaee17920a7c525d3c7e15f18ea9a2e..14bd5c079ca3e0f96fd3aa0889336647a4f92b84 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3596,7 +3596,8 @@ static int kvm_vm_ioctl_set_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps)
               sizeof(kvm->arch.vpit->pit_state.channels));
        kvm->arch.vpit->pit_state.flags = ps->flags;
        for (i = 0; i < 3; i++)
-               kvm_pit_load_count(kvm, i, kvm->arch.vpit->pit_state.channels[i].count, start);
+               kvm_pit_load_count(kvm, i, kvm->arch.vpit->pit_state.channels[i].count,
+                                  start && i == 0);
        mutex_unlock(&kvm->arch.vpit->pit_state.lock);
        return r;
 }