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KVM: PIT support for HPET legacy mode

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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>
This commit is contained in:
Beth Kon
2009-07-07 11:50:38 -04:00
committed by Avi Kivity
parent 0d1de2d901
commit e9f4275732
5 changed files with 93 additions and 6 deletions
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59
arch/x86/kvm/x86.c
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@@ -1213,6 +1213,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_ASSIGN_DEV_IRQ:
case KVM_CAP_IRQFD:
case KVM_CAP_PIT2:
case KVM_CAP_PIT_STATE2:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
@@ -2078,7 +2079,36 @@ static int kvm_vm_ioctl_set_pit(struct kvm *kvm, struct kvm_pit_state *ps)
mutex_lock(&kvm->arch.vpit->pit_state.lock);
memcpy(&kvm->arch.vpit->pit_state, ps, sizeof(struct kvm_pit_state));
kvm_pit_load_count(kvm, 0, ps->channels[0].count);
kvm_pit_load_count(kvm, 0, ps->channels[0].count, 0);
mutex_unlock(&kvm->arch.vpit->pit_state.lock);
return r;
}
static int kvm_vm_ioctl_get_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps)
{
int r = 0;
mutex_lock(&kvm->arch.vpit->pit_state.lock);
memcpy(ps->channels, &kvm->arch.vpit->pit_state.channels,
sizeof(ps->channels));
ps->flags = kvm->arch.vpit->pit_state.flags;
mutex_unlock(&kvm->arch.vpit->pit_state.lock);
return r;
}
static int kvm_vm_ioctl_set_pit2(struct kvm *kvm, struct kvm_pit_state2 *ps)
{
int r = 0, start = 0;
u32 prev_legacy, cur_legacy;
mutex_lock(&kvm->arch.vpit->pit_state.lock);
prev_legacy = kvm->arch.vpit->pit_state.flags & KVM_PIT_FLAGS_HPET_LEGACY;
cur_legacy = ps->flags & KVM_PIT_FLAGS_HPET_LEGACY;
if (!prev_legacy && cur_legacy)
start = 1;
memcpy(&kvm->arch.vpit->pit_state.channels, &ps->channels,
sizeof(kvm->arch.vpit->pit_state.channels));
kvm->arch.vpit->pit_state.flags = ps->flags;
kvm_pit_load_count(kvm, 0, kvm->arch.vpit->pit_state.channels[0].count, start);
mutex_unlock(&kvm->arch.vpit->pit_state.lock);
return r;
}
@@ -2140,6 +2170,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
*/
union {
struct kvm_pit_state ps;
struct kvm_pit_state2 ps2;
struct kvm_memory_alias alias;
struct kvm_pit_config pit_config;
} u;
@@ -2322,6 +2353,32 @@ long kvm_arch_vm_ioctl(struct file *filp,
r = 0;
break;
}
case KVM_GET_PIT2: {
r = -ENXIO;
if (!kvm->arch.vpit)
goto out;
r = kvm_vm_ioctl_get_pit2(kvm, &u.ps2);
if (r)
goto out;
r = -EFAULT;
if (copy_to_user(argp, &u.ps2, sizeof(u.ps2)))
goto out;
r = 0;
break;
}
case KVM_SET_PIT2: {
r = -EFAULT;
if (copy_from_user(&u.ps2, argp, sizeof(u.ps2)))
goto out;
r = -ENXIO;
if (!kvm->arch.vpit)
goto out;
r = kvm_vm_ioctl_set_pit2(kvm, &u.ps2);
if (r)
goto out;
r = 0;
break;
}
case KVM_REINJECT_CONTROL: {
struct kvm_reinject_control control;
r = -EFAULT;