KVM: In kernel PIT model

The patch moves the PIT model from userspace to kernel, and increases
the timer accuracy greatly.

[marcelo: make last_injected_time per-guest]
Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Tested-and-Acked-by: Alex Davis <alex14641@yahoo.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/x86/kvm/Makefile

@@ -6,7 +6,8 @@ common-objs = $(addprefix ../../../virt/kvm/, kvm_main.o ioapic.o)
 
 EXTRA_CFLAGS += -Ivirt/kvm -Iarch/x86/kvm
 
-kvm-objs := $(common-objs) x86.o mmu.o x86_emulate.o i8259.o irq.o lapic.o
+kvm-objs := $(common-objs) x86.o mmu.o x86_emulate.o i8259.o irq.o lapic.o \
+	i8254.o
 obj-$(CONFIG_KVM) += kvm.o
 kvm-intel-objs = vmx.o
 obj-$(CONFIG_KVM_INTEL) += kvm-intel.o

arch/x86/kvm/i8254.h

+#ifndef __I8254_H
+#define __I8254_H
+
+#include "iodev.h"
+
+struct kvm_kpit_timer {
+	struct hrtimer timer;
+	int irq;
+	s64 period; /* unit: ns */
+	s64 scheduled;
+	ktime_t last_update;
+	atomic_t pending;
+};
+
+struct kvm_kpit_channel_state {
+	u32 count; /* can be 65536 */
+	u16 latched_count;
+	u8 count_latched;
+	u8 status_latched;
+	u8 status;
+	u8 read_state;
+	u8 write_state;
+	u8 write_latch;
+	u8 rw_mode;
+	u8 mode;
+	u8 bcd; /* not supported */
+	u8 gate; /* timer start */
+	ktime_t count_load_time;
+};
+
+struct kvm_kpit_state {
+	struct kvm_kpit_channel_state channels[3];
+	struct kvm_kpit_timer pit_timer;
+	u32    speaker_data_on;
+	struct mutex lock;
+	struct kvm_pit *pit;
+	bool inject_pending; /* if inject pending interrupts */
+	unsigned long last_injected_time;
+};
+
+struct kvm_pit {
+	unsigned long base_addresss;
+	struct kvm_io_device dev;
+	struct kvm_io_device speaker_dev;
+	struct kvm *kvm;
+	struct kvm_kpit_state pit_state;
+};
+
+#define KVM_PIT_BASE_ADDRESS	    0x40
+#define KVM_SPEAKER_BASE_ADDRESS    0x61
+#define KVM_PIT_MEM_LENGTH	    4
+#define KVM_PIT_FREQ		    1193181
+#define KVM_MAX_PIT_INTR_INTERVAL   HZ / 100
+#define KVM_PIT_CHANNEL_MASK	    0x3
+
+void kvm_inject_pit_timer_irqs(struct kvm_vcpu *vcpu);
+void kvm_pit_timer_intr_post(struct kvm_vcpu *vcpu, int vec);
+struct kvm_pit *kvm_create_pit(struct kvm *kvm);
+void kvm_free_pit(struct kvm *kvm);
+
+#endif

arch/x86/kvm/irq.c

@@ -23,6 +23,7 @@
 #include <linux/kvm_host.h>
 
 #include "irq.h"
+#include "i8254.h"
 
 /*
  * check if there is pending interrupt without
@@ -66,6 +67,7 @@ EXPORT_SYMBOL_GPL(kvm_cpu_get_interrupt);
 void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu)
 {
 	kvm_inject_apic_timer_irqs(vcpu);
+	kvm_inject_pit_timer_irqs(vcpu);
 	/* TODO: PIT, RTC etc. */
 }
 EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs);
@@ -73,6 +75,7 @@ EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs);
 void kvm_timer_intr_post(struct kvm_vcpu *vcpu, int vec)
 {
 	kvm_apic_timer_intr_post(vcpu, vec);
+	kvm_pit_timer_intr_post(vcpu, vec);
 	/* TODO: PIT, RTC etc. */
 }
 EXPORT_SYMBOL_GPL(kvm_timer_intr_post);

arch/x86/kvm/x86.c

@@ -17,6 +17,7 @@
 #include <linux/kvm_host.h>
 #include "irq.h"
 #include "mmu.h"
+#include "i8254.h"
 
 #include <linux/clocksource.h>
 #include <linux/kvm.h>
@@ -818,6 +819,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_SET_TSS_ADDR:
 	case KVM_CAP_EXT_CPUID:
 	case KVM_CAP_CLOCKSOURCE:
+	case KVM_CAP_PIT:
 		r = 1;
 		break;
 	case KVM_CAP_VAPIC:
@@ -1594,6 +1596,12 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		} else
 			goto out;
 		break;
+	case KVM_CREATE_PIT:
+		r = -ENOMEM;
+		kvm->arch.vpit = kvm_create_pit(kvm);
+		if (kvm->arch.vpit)
+			r = 0;
+		break;
 	case KVM_IRQ_LINE: {
 		struct kvm_irq_level irq_event;
 
@@ -3372,6 +3380,7 @@ static void kvm_free_vcpus(struct kvm *kvm)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
+	kvm_free_pit(kvm);
 	kfree(kvm->arch.vpic);
 	kfree(kvm->arch.vioapic);
 	kvm_free_vcpus(kvm);

include/asm-x86/kvm_host.h

@@ -298,6 +298,7 @@ struct kvm_arch{
 	struct list_head active_mmu_pages;
 	struct kvm_pic *vpic;
 	struct kvm_ioapic *vioapic;
+	struct kvm_pit *vpit;
 
 	int round_robin_prev_vcpu;
 	unsigned int tss_addr;

include/linux/kvm.h

@@ -236,6 +236,7 @@ struct kvm_vapic_addr {
 #define KVM_CAP_CLOCKSOURCE 8
 #define KVM_CAP_NR_VCPUS 9       /* returns max vcpus per vm */
 #define KVM_CAP_NR_MEMSLOTS 10   /* returns max memory slots per vm */
+#define KVM_CAP_PIT 11
 
 /*
  * ioctls for VM fds
@@ -258,6 +259,7 @@ struct kvm_vapic_addr {
 #define KVM_IRQ_LINE		  _IOW(KVMIO, 0x61, struct kvm_irq_level)
 #define KVM_GET_IRQCHIP		  _IOWR(KVMIO, 0x62, struct kvm_irqchip)
 #define KVM_SET_IRQCHIP		  _IOR(KVMIO,  0x63, struct kvm_irqchip)
+#define KVM_CREATE_PIT		  _IO(KVMIO,  0x64)
 
 /*
  * ioctls for vcpu fds