kvm_main.c

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/*
 * Kernel-based Virtual Machine driver for Linux
 *
 * This module enables machines with Intel VT-x extensions to run virtual
 * machines without emulation or binary translation.
 *
 * Copyright (C) 2006 Qumranet, Inc.
 *
 * Authors:
 *   Avi Kivity   <[e-mail]>
 *   Yaniv Kamay  <[e-mail]>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 */

#include "kvm.h"
#include "x86_emulate.h"
#include "segment_descriptor.h"
#include "irq.h"

#include <linux/kvm.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/percpu.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/vmalloc.h>
#include <linux/reboot.h>
#include <linux/debugfs.h>
#include <linux/highmem.h>
#include <linux/file.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
#include <linux/anon_inodes.h>
#include <linux/profile.h>

#include <asm/processor.h>
#include <asm/msr.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/desc.h>

MODULE_AUTHOR("Qumranet");
MODULE_LICENSE("GPL");

static DEFINE_SPINLOCK(kvm_lock);
static LIST_HEAD(vm_list);

static cpumask_t cpus_hardware_enabled;

struct kvm_x86_ops *kvm_x86_ops;
struct kmem_cache *kvm_vcpu_cache;
EXPORT_SYMBOL_GPL(kvm_vcpu_cache);

static __read_mostly struct preempt_ops kvm_preempt_ops;

#define STAT_OFFSET(x) offsetof(struct kvm_vcpu, stat.x)

static struct kvm_stats_debugfs_item {
	const char *name;
	int offset;
	struct dentry *dentry;
} debugfs_entries[] = {
	{ "pf_fixed", STAT_OFFSET(pf_fixed) },
	{ "pf_guest", STAT_OFFSET(pf_guest) },
	{ "tlb_flush", STAT_OFFSET(tlb_flush) },
	{ "invlpg", STAT_OFFSET(invlpg) },
	{ "exits", STAT_OFFSET(exits) },
	{ "io_exits", STAT_OFFSET(io_exits) },
	{ "mmio_exits", STAT_OFFSET(mmio_exits) },
	{ "signal_exits", STAT_OFFSET(signal_exits) },
	{ "irq_window", STAT_OFFSET(irq_window_exits) },
	{ "halt_exits", STAT_OFFSET(halt_exits) },
	{ "halt_wakeup", STAT_OFFSET(halt_wakeup) },
	{ "request_irq", STAT_OFFSET(request_irq_exits) },
	{ "irq_exits", STAT_OFFSET(irq_exits) },
	{ "light_exits", STAT_OFFSET(light_exits) },
	{ "efer_reload", STAT_OFFSET(efer_reload) },
	{ NULL }
};

static struct dentry *debugfs_dir;

#define MAX_IO_MSRS 256

#define CR0_RESERVED_BITS						\
	(~(unsigned long)(X86_CR0_PE | X86_CR0_MP | X86_CR0_EM | X86_CR0_TS \
			  | X86_CR0_ET | X86_CR0_NE | X86_CR0_WP | X86_CR0_AM \
			  | X86_CR0_NW | X86_CR0_CD | X86_CR0_PG))
#define CR4_RESERVED_BITS						\
	(~(unsigned long)(X86_CR4_VME | X86_CR4_PVI | X86_CR4_TSD | X86_CR4_DE\
			  | X86_CR4_PSE | X86_CR4_PAE | X86_CR4_MCE	\
			  | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR	\
			  | X86_CR4_OSXMMEXCPT | X86_CR4_VMXE))

#define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
#define EFER_RESERVED_BITS 0xfffffffffffff2fe

#ifdef CONFIG_X86_64
// LDT or TSS descriptor in the GDT. 16 bytes.
struct segment_descriptor_64 {
	struct segment_descriptor s;
	u32 base_higher;
	u32 pad_zero;
};

#endif

static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
			   unsigned long arg);

unsigned long segment_base(u16 selector)
{
	struct descriptor_table gdt;
	struct segment_descriptor *d;
	unsigned long table_base;
	typedef unsigned long ul;
	unsigned long v;

	if (selector == 0)
		return 0;

	asm ("sgdt %0" : "=m"(gdt));
	table_base = gdt.base;

	if (selector & 4) {           /* from ldt */
		u16 ldt_selector;

		asm ("sldt %0" : "=g"(ldt_selector));
		table_base = segment_base(ldt_selector);
	}
	d = (struct segment_descriptor *)(table_base + (selector & ~7));
	v = d->base_low | ((ul)d->base_mid << 16) | ((ul)d->base_high << 24);
#ifdef CONFIG_X86_64
	if (d->system == 0
	    && (d->type == 2 || d->type == 9 || d->type == 11))
		v |= ((ul)((struct segment_descriptor_64 *)d)->base_higher) << 32;
#endif
	return v;
}
EXPORT_SYMBOL_GPL(segment_base);

static inline int valid_vcpu(int n)
{
	return likely(n >= 0 && n < KVM_MAX_VCPUS);
}

void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
{
	if (!vcpu->fpu_active || vcpu->guest_fpu_loaded)
		return;

	vcpu->guest_fpu_loaded = 1;
	fx_save(&vcpu->host_fx_image);
	fx_restore(&vcpu->guest_fx_image);
}
EXPORT_SYMBOL_GPL(kvm_load_guest_fpu);

void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
{
	if (!vcpu->guest_fpu_loaded)
		return;

	vcpu->guest_fpu_loaded = 0;
	fx_save(&vcpu->guest_fx_image);
	fx_restore(&vcpu->host_fx_image);
}
EXPORT_SYMBOL_GPL(kvm_put_guest_fpu);

/*
 * Switches to specified vcpu, until a matching vcpu_put()
 */
static void vcpu_load(struct kvm_vcpu *vcpu)
{
	int cpu;

	mutex_lock(&vcpu->mutex);
	cpu = get_cpu();
	preempt_notifier_register(&vcpu->preempt_notifier);
	kvm_x86_ops->vcpu_load(vcpu, cpu);
	put_cpu();
}

static void vcpu_put(struct kvm_vcpu *vcpu)
{
	preempt_disable();
	kvm_x86_ops->vcpu_put(vcpu);
	preempt_notifier_unregister(&vcpu->preempt_notifier);
	preempt_enable();
	mutex_unlock(&vcpu->mutex);
}

static void ack_flush(void *_completed)
{
}

void kvm_flush_remote_tlbs(struct kvm *kvm)
{
	int i, cpu;
	cpumask_t cpus;
	struct kvm_vcpu *vcpu;

	cpus_clear(cpus);
	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
		vcpu = kvm->vcpus[i];
		if (!vcpu)
			continue;
		if (test_and_set_bit(KVM_TLB_FLUSH, &vcpu->requests))
			continue;
		cpu = vcpu->cpu;
		if (cpu != -1 && cpu != raw_smp_processor_id())
			cpu_set(cpu, cpus);
	}
	smp_call_function_mask(cpus, ack_flush, NULL, 1);
}

int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
{
	struct page *page;
	int r;

	mutex_init(&vcpu->mutex);
	vcpu->cpu = -1;
	vcpu->mmu.root_hpa = INVALID_PAGE;
	vcpu->kvm = kvm;
	vcpu->vcpu_id = id;
	if (!irqchip_in_kernel(kvm) || id == 0)
		vcpu->mp_state = VCPU_MP_STATE_RUNNABLE;
	else
		vcpu->mp_state = VCPU_MP_STATE_UNINITIALIZED;
	init_waitqueue_head(&vcpu->wq);

	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
	if (!page) {
		r = -ENOMEM;
		goto fail;
	}
	vcpu->run = page_address(page);

	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
	if (!page) {
		r = -ENOMEM;
		goto fail_free_run;
	}
	vcpu->pio_data = page_address(page);

	r = kvm_mmu_create(vcpu);
	if (r < 0)
		goto fail_free_pio_data;

	return 0;

fail_free_pio_data:
	free_page((unsigned long)vcpu->pio_data);
fail_free_run:
	free_page((unsigned long)vcpu->run);
fail:
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(kvm_vcpu_init);

void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
{
	kvm_mmu_destroy(vcpu);
	if (vcpu->apic)
		hrtimer_cancel(&vcpu->apic->timer.dev);
	kvm_free_apic(vcpu->apic);
	free_page((unsigned long)vcpu->pio_data);
	free_page((unsigned long)vcpu->run);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);

static struct kvm *kvm_create_vm(void)
{
	struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);

	if (!kvm)
		return ERR_PTR(-ENOMEM);

	kvm_io_bus_init(&kvm->pio_bus);
	mutex_init(&kvm->lock);
	INIT_LIST_HEAD(&kvm->active_mmu_pages);
	kvm_io_bus_init(&kvm->mmio_bus);
	spin_lock(&kvm_lock);
	list_add(&kvm->vm_list, &vm_list);
	spin_unlock(&kvm_lock);
	return kvm;
}

/*
 * Free any memory in @free but not in @dont.
 */
static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
				  struct kvm_memory_slot *dont)
{
	int i;

	if (!dont || free->phys_mem != dont->phys_mem)
		if (free->phys_mem) {
			for (i = 0; i < free->npages; ++i)
				if (free->phys_mem[i])
					__free_page(free->phys_mem[i]);
			vfree(free->phys_mem);
		}

	if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
		vfree(free->dirty_bitmap);

	free->phys_mem = NULL;
	free->npages = 0;
	free->dirty_bitmap = NULL;
}

static void kvm_free_physmem(struct kvm *kvm)
{
	int i;

	for (i = 0; i < kvm->nmemslots; ++i)
		kvm_free_physmem_slot(&kvm->memslots[i], NULL);
}

static void free_pio_guest_pages(struct kvm_vcpu *vcpu)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(vcpu->pio.guest_pages); ++i)
		if (vcpu->pio.guest_pages[i]) {
			__free_page(vcpu->pio.guest_pages[i]);
			vcpu->pio.guest_pages[i] = NULL;
		}
}

static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
{
	vcpu_load(vcpu);
	kvm_mmu_unload(vcpu);
	vcpu_put(vcpu);
}

static void kvm_free_vcpus(struct kvm *kvm)
{
	unsigned int i;

	/*
	 * Unpin any mmu pages first.
	 */
	for (i = 0; i < KVM_MAX_VCPUS; ++i)
		if (kvm->vcpus[i])
			kvm_unload_vcpu_mmu(kvm->vcpus[i]);
	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
		if (kvm->vcpus[i]) {
			kvm_x86_ops->vcpu_free(kvm->vcpus[i]);
			kvm->vcpus[i] = NULL;
		}
	}

}

static void kvm_destroy_vm(struct kvm *kvm)
{
	spin_lock(&kvm_lock);
	list_del(&kvm->vm_list);
	spin_unlock(&kvm_lock);
	kvm_io_bus_destroy(&kvm->pio_bus);
	kvm_io_bus_destroy(&kvm->mmio_bus);
	kfree(kvm->vpic);
	kfree(kvm->vioapic);
	kvm_free_vcpus(kvm);
	kvm_free_physmem(kvm);
	kfree(kvm);
}

static int kvm_vm_release(struct inode *inode, struct file *filp)
{
	struct kvm *kvm = filp->private_data;

	kvm_destroy_vm(kvm);
	return 0;
}

static void inject_gp(struct kvm_vcpu *vcpu)
{
	kvm_x86_ops->inject_gp(vcpu, 0);
}

/*
 * Load the pae pdptrs.  Return true is they are all valid.
 */
static int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
{
	gfn_t pdpt_gfn = cr3 >> PAGE_SHIFT;
	unsigned offset = ((cr3 & (PAGE_SIZE-1)) >> 5) << 2;
	int i;
	u64 *pdpt;
	int ret;
	struct page *page;
	u64 pdpte[ARRAY_SIZE(vcpu->pdptrs)];

	mutex_lock(&vcpu->kvm->lock);
	page = gfn_to_page(vcpu->kvm, pdpt_gfn);
	if (!page) {
		ret = 0;
		goto out;
	}

	pdpt = kmap_atomic(page, KM_USER0);
	memcpy(pdpte, pdpt+offset, sizeof(pdpte));
	kunmap_atomic(pdpt, KM_USER0);

	for (i = 0; i < ARRAY_SIZE(pdpte); ++i) {
		if ((pdpte[i] & 1) && (pdpte[i] & 0xfffffff0000001e6ull)) {
			ret = 0;
			goto out;
		}
	}
	ret = 1;

	memcpy(vcpu->pdptrs, pdpte, sizeof(vcpu->pdptrs));
out:
	mutex_unlock(&vcpu->kvm->lock);

	return ret;
}

void set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
{
	if (cr0 & CR0_RESERVED_BITS) {
		printk(KERN_DEBUG "set_cr0: 0x%lx #GP, reserved bits 0x%lx\n",
		       cr0, vcpu->cr0);
		inject_gp(vcpu);
		return;
	}

	if ((cr0 & X86_CR0_NW) && !(cr0 & X86_CR0_CD)) {
		printk(KERN_DEBUG "set_cr0: #GP, CD == 0 && NW == 1\n");
		inject_gp(vcpu);
		return;
	}

	if ((cr0 & X86_CR0_PG) && !(cr0 & X86_CR0_PE)) {
		printk(KERN_DEBUG "set_cr0: #GP, set PG flag "
		       "and a clear PE flag\n");
		inject_gp(vcpu);
		return;
	}

	if (!is_paging(vcpu) && (cr0 & X86_CR0_PG)) {
#ifdef CONFIG_X86_64
		if ((vcpu->shadow_efer & EFER_LME)) {
			int cs_db, cs_l;

			if (!is_pae(vcpu)) {
				printk(KERN_DEBUG "set_cr0: #GP, start paging "
				       "in long mode while PAE is disabled\n");
				inject_gp(vcpu);
				return;
			}
			kvm_x86_ops->get_cs_db_l_bits(vcpu, &cs_db, &cs_l);
			if (cs_l) {
				printk(KERN_DEBUG "set_cr0: #GP, start paging "
				       "in long mode while CS.L == 1\n");
				inject_gp(vcpu);
				return;

			}
		} else
#endif
		if (is_pae(vcpu) && !load_pdptrs(vcpu, vcpu->cr3)) {
			printk(KERN_DEBUG "set_cr0: #GP, pdptrs "
			       "reserved bits\n");
			inject_gp(vcpu);
			return;
		}

	}

	kvm_x86_ops->set_cr0(vcpu, cr0);
	vcpu->cr0 = cr0;

	mutex_lock(&vcpu->kvm->lock);
	kvm_mmu_reset_context(vcpu);
	mutex_unlock(&vcpu->kvm->lock);
	return;
}
EXPORT_SYMBOL_GPL(set_cr0);

void lmsw(struct kvm_vcpu *vcpu, unsigned long msw)
{
	set_cr0(vcpu, (vcpu->cr0 & ~0x0ful) | (msw & 0x0f));
}
EXPORT_SYMBOL_GPL(lmsw);

void set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
{
	if (cr4 & CR4_RESERVED_BITS) {
		printk(KERN_DEBUG "set_cr4: #GP, reserved bits\n");
		inject_gp(vcpu);
		return;
	}

	if (is_long_mode(vcpu)) {
		if (!(cr4 & X86_CR4_PAE)) {
			printk(KERN_DEBUG "set_cr4: #GP, clearing PAE while "
			       "in long mode\n");
			inject_gp(vcpu);
			return;
		}
	} else if (is_paging(vcpu) && !is_pae(vcpu) && (cr4 & X86_CR4_PAE)
		   && !load_pdptrs(vcpu, vcpu->cr3)) {
		printk(KERN_DEBUG "set_cr4: #GP, pdptrs reserved bits\n");
		inject_gp(vcpu);
		return;
	}

	if (cr4 & X86_CR4_VMXE) {
		printk(KERN_DEBUG "set_cr4: #GP, setting VMXE\n");
		inject_gp(vcpu);
		return;
	}
	kvm_x86_ops->set_cr4(vcpu, cr4);
	vcpu->cr4 = cr4;
	mutex_lock(&vcpu->kvm->lock);
	kvm_mmu_reset_context(vcpu);
	mutex_unlock(&vcpu->kvm->lock);
}
EXPORT_SYMBOL_GPL(set_cr4);

void set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
{
	if (is_long_mode(vcpu)) {
		if (cr3 & CR3_L_MODE_RESERVED_BITS) {
			printk(KERN_DEBUG "set_cr3: #GP, reserved bits\n");
			inject_gp(vcpu);
			return;
		}
	} else {
		if (is_pae(vcpu)) {
			if (cr3 & CR3_PAE_RESERVED_BITS) {
				printk(KERN_DEBUG
				       "set_cr3: #GP, reserved bits\n");
				inject_gp(vcpu);
				return;
			}
			if (is_paging(vcpu) && !load_pdptrs(vcpu, cr3)) {
				printk(KERN_DEBUG "set_cr3: #GP, pdptrs "
				       "reserved bits\n");
				inject_gp(vcpu);
				return;
			}
		} else {
			if (cr3 & CR3_NONPAE_RESERVED_BITS) {
				printk(KERN_DEBUG
				       "set_cr3: #GP, reserved bits\n");
				inject_gp(vcpu);
				return;
			}
		}
	}