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authorBeth Kon <eak@us.ibm.com>2009-07-07 17:50:38 +0200
committerAvi Kivity <avi@redhat.com>2009-09-10 07:33:12 +0200
commite9f4275732add046fed4a548b8dbb98dbe500d2f (patch)
tree8d9e22bbc6a9557f95712aaa98534d5983034252 /arch/x86/kvm/i8254.c
parentKVM: Always report x2apic as supported feature (diff)
downloadlinux-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.c22
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;