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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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9
arch/x86/include/asm/kvm.h
View file

@ -18,6 +18,7 @@
#define __KVM_HAVE_GUEST_DEBUG
#define __KVM_HAVE_MSIX
#define __KVM_HAVE_MCE
#define __KVM_HAVE_PIT_STATE2
/* Architectural interrupt line count. */
#define KVM_NR_INTERRUPTS 256
@ -237,6 +238,14 @@ struct kvm_pit_state {
struct kvm_pit_channel_state channels[3];
};
#define KVM_PIT_FLAGS_HPET_LEGACY 0x00000001
struct kvm_pit_state2 {
struct kvm_pit_channel_state channels[3];
__u32 flags;
__u32 reserved[9];
};
struct kvm_reinject_control {
__u8 pit_reinject;
__u8 reserved[31];

22
arch/x86/kvm/i8254.c
View file

@ -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;

3
arch/x86/kvm/i8254.h
View file

@ -21,6 +21,7 @@ struct kvm_kpit_channel_state {
struct kvm_kpit_state {
struct kvm_kpit_channel_state channels[3];
u32 flags;
struct kvm_timer pit_timer;
bool is_periodic;
u32 speaker_data_on;
@ -49,7 +50,7 @@ struct kvm_pit {
#define KVM_PIT_CHANNEL_MASK 0x3
void kvm_inject_pit_timer_irqs(struct kvm_vcpu *vcpu);
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);
struct kvm_pit *kvm_create_pit(struct kvm *kvm, u32 flags);
void kvm_free_pit(struct kvm *kvm);
void kvm_pit_reset(struct kvm_pit *pit);

59
arch/x86/kvm/x86.c
View file

@ -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;

6
include/linux/kvm.h
View file

@ -409,6 +409,9 @@ struct kvm_guest_debug {
#define KVM_CAP_PIT2 33
#endif
#define KVM_CAP_SET_BOOT_CPU_ID 34
#ifdef __KVM_HAVE_PIT_STATE2
#define KVM_CAP_PIT_STATE2 35
#endif
#ifdef KVM_CAP_IRQ_ROUTING
@ -586,6 +589,9 @@ struct kvm_debug_guest {
#define KVM_IA64_VCPU_GET_STACK _IOR(KVMIO, 0x9a, void *)
#define KVM_IA64_VCPU_SET_STACK _IOW(KVMIO, 0x9b, void *)
#define KVM_GET_PIT2 _IOR(KVMIO, 0x9f, struct kvm_pit_state2)
#define KVM_SET_PIT2 _IOW(KVMIO, 0xa0, struct kvm_pit_state2)
#define KVM_TRC_INJ_VIRQ (KVM_TRC_HANDLER + 0x02)
#define KVM_TRC_REDELIVER_EVT (KVM_TRC_HANDLER + 0x03)
#define KVM_TRC_PEND_INTR (KVM_TRC_HANDLER + 0x04)