Commit e9f42757 authored by Beth Kon's avatar Beth Kon Committed by Avi Kivity
Browse files

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: default avatarBeth Kon <eak@us.ibm.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 0d1de2d9

arch/x86/include/asm/kvm.h

+9 −0
Original line number Diff line number Diff line
@@ -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];

arch/x86/kvm/i8254.c

+18 −4
Original line number Diff line number Diff line
@@ -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:

		if (!(ps->flags & KVM_PIT_FLAGS_HPET_LEGACY)) {

			create_pit_timer(ps, val, 0);

		}

		break;

	case 2:

	case 3:

		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)

{

	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;

arch/x86/kvm/i8254.h

+2 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/x86.c

+58 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/kvm.h

+6 −0
Original line number Diff line number Diff line
@@ -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)

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