diff options
author | Beth Kon <eak@us.ibm.com> | 2009-07-07 17:50:38 +0200 |
---|---|---|
committer | Avi Kivity <avi@redhat.com> | 2009-09-10 07:33:12 +0200 |
commit | e9f4275732add046fed4a548b8dbb98dbe500d2f (patch) | |
tree | 8d9e22bbc6a9557f95712aaa98534d5983034252 /arch/x86/kvm/i8254.c | |
parent | KVM: Always report x2apic as supported feature (diff) | |
download | linux-e9f4275732add046fed4a548b8dbb98dbe500d2f.tar.xz linux-e9f4275732add046fed4a548b8dbb98dbe500d2f.zip |
KVM: PIT support for HPET legacy mode
When kvm is in hpet_legacy_mode, the hpet is providing the timer
interrupt and the pit should not be. So in legacy mode, the pit timer
is destroyed, but the *state* of the pit is maintained. So if kvm or
the guest tries to modify the state of the pit, this modification is
accepted, *except* that the timer isn't actually started. When we exit
hpet_legacy_mode, the current state of the pit (which is up to date
since we've been accepting modifications) is used to restart the pit
timer.
The saved_mode code in kvm_pit_load_count temporarily changes mode to
0xff in order to destroy the timer, but then restores the actual
value, again maintaining "current" state of the pit for possible later
reenablement.
[avi: add some reserved storage in the ioctl; make SET_PIT2 IOW]
[marcelo: fix memory corruption due to reserved storage]
Signed-off-by: Beth Kon <eak@us.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/i8254.c')
-rw-r--r-- | arch/x86/kvm/i8254.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 8c3ac30ef9bd..9b62c57ba6e4 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -332,20 +332,33 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val) case 1: /* FIXME: enhance mode 4 precision */ case 4: - create_pit_timer(ps, val, 0); + if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) { + create_pit_timer(ps, val, 0); + } break; case 2: case 3: - create_pit_timer(ps, val, 1); + if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)){ + create_pit_timer(ps, val, 1); + } break; default: destroy_pit_timer(&ps->pit_timer); } } -void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val) +void kvm_pit_load_count(struct kvm *kvm, int channel, u32 val, int hpet_legacy_start) { - pit_load_count(kvm, channel, val); + u8 saved_mode; + if (hpet_legacy_start) { + /* save existing mode for later reenablement */ + 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); + kvm->arch.vpit->pit_state.channels[0].mode = saved_mode; + } else { + pit_load_count(kvm, channel, val); + } } static inline struct kvm_pit *dev_to_pit(struct kvm_io_device *dev) @@ -554,6 +567,7 @@ void kvm_pit_reset(struct kvm_pit *pit) struct kvm_kpit_channel_state *c; mutex_lock(&pit->pit_state.lock); + pit->pit_state.flags = 0; for (i = 0; i < 3; i++) { c = &pit->pit_state.channels[i]; c->mode = 0xff; |