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>
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 708b9c3..4a5fe91 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -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_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];
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 8c3ac30..9b62c57 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -332,20 +332,33 @@
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 @@
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;
diff --git a/arch/x86/kvm/i8254.h b/arch/x86/kvm/i8254.h
index b267018..d4c1c7f 100644
--- a/arch/x86/kvm/i8254.h
+++ b/arch/x86/kvm/i8254.h
@@ -21,6 +21,7 @@
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 @@
#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);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dfb0e37..2214384 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1213,6 +1213,7 @@
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 @@
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 @@
*/
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 @@
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;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 76c6408..a74a1fc 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -409,6 +409,9 @@
#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 @@
#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)