virt/kvm/arm/vgic.c

/*
 * Copyright (C) 2012 ARM Ltd.
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/cpu.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/uaccess.h>

#include <linux/irqchip/arm-gic.h>

#include <asm/kvm_emulate.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_mmu.h>

/*
 * How the whole thing works (courtesy of Christoffer Dall):
 *
 * - At any time, the dist->irq_pending_on_cpu is the oracle that knows if
 *   something is pending on the CPU interface.
 * - Interrupts that are pending on the distributor are stored on the
 *   vgic.irq_pending vgic bitmap (this bitmap is updated by both user land
 *   ioctls and guest mmio ops, and other in-kernel peripherals such as the
 *   arch. timers).
 * - Every time the bitmap changes, the irq_pending_on_cpu oracle is
 *   recalculated
 * - To calculate the oracle, we need info for each cpu from
 *   compute_pending_for_cpu, which considers:
 *   - PPI: dist->irq_pending & dist->irq_enable
 *   - SPI: dist->irq_pending & dist->irq_enable & dist->irq_spi_target
 *   - irq_spi_target is a 'formatted' version of the GICD_ITARGETSRn
 *     registers, stored on each vcpu. We only keep one bit of
 *     information per interrupt, making sure that only one vcpu can
 *     accept the interrupt.
 * - If any of the above state changes, we must recalculate the oracle.
 * - The same is true when injecting an interrupt, except that we only
 *   consider a single interrupt at a time. The irq_spi_cpu array
 *   contains the target CPU for each SPI.
 *
 * The handling of level interrupts adds some extra complexity. We
 * need to track when the interrupt has been EOIed, so we can sample
 * the 'line' again. This is achieved as such:
 *
 * - When a level interrupt is moved onto a vcpu, the corresponding
 *   bit in irq_queued is set. As long as this bit is set, the line
 *   will be ignored for further interrupts. The interrupt is injected
 *   into the vcpu with the GICH_LR_EOI bit set (generate a
 *   maintenance interrupt on EOI).
 * - When the interrupt is EOIed, the maintenance interrupt fires,
 *   and clears the corresponding bit in irq_queued. This allows the
 *   interrupt line to be sampled again.
 * - Note that level-triggered interrupts can also be set to pending from
 *   writes to GICD_ISPENDRn and lowering the external input line does not
 *   cause the interrupt to become inactive in such a situation.
 *   Conversely, writes to GICD_ICPENDRn do not cause the interrupt to become
 *   inactive as long as the external input line is held high.
 */

#define VGIC_ADDR_UNDEF		(-1)
#define IS_VGIC_ADDR_UNDEF(_x)  ((_x) == VGIC_ADDR_UNDEF)

#define PRODUCT_ID_KVM		0x4b	/* ASCII code K */
#define IMPLEMENTER_ARM		0x43b
#define GICC_ARCH_VERSION_V2	0x2

#define ACCESS_READ_VALUE	(1 << 0)
#define ACCESS_READ_RAZ		(0 << 0)
#define ACCESS_READ_MASK(x)	((x) & (1 << 0))
#define ACCESS_WRITE_IGNORED	(0 << 1)
#define ACCESS_WRITE_SETBIT	(1 << 1)
#define ACCESS_WRITE_CLEARBIT	(2 << 1)
#define ACCESS_WRITE_VALUE	(3 << 1)
#define ACCESS_WRITE_MASK(x)	((x) & (3 << 1))

static void vgic_retire_disabled_irqs(struct kvm_vcpu *vcpu);
static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu);
static void vgic_update_state(struct kvm *kvm);
static void vgic_kick_vcpus(struct kvm *kvm);
static u8 *vgic_get_sgi_sources(struct vgic_dist *dist, int vcpu_id, int sgi);
static void vgic_dispatch_sgi(struct kvm_vcpu *vcpu, u32 reg);
static struct vgic_lr vgic_get_lr(const struct kvm_vcpu *vcpu, int lr);
static void vgic_set_lr(struct kvm_vcpu *vcpu, int lr, struct vgic_lr lr_desc);
static void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);
static void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr);

static const struct vgic_ops *vgic_ops;
static const struct vgic_params *vgic;

/*
 * struct vgic_bitmap contains a bitmap made of unsigned longs, but
 * extracts u32s out of them.
 *
 * This does not work on 64-bit BE systems, because the bitmap access
 * will store two consecutive 32-bit words with the higher-addressed
 * register's bits at the lower index and the lower-addressed register's
 * bits at the higher index.
 *
 * Therefore, swizzle the register index when accessing the 32-bit word
 * registers to access the right register's value.
 */
#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 64
#define REG_OFFSET_SWIZZLE	1
#else
#define REG_OFFSET_SWIZZLE	0
#endif

static int vgic_init_bitmap(struct vgic_bitmap *b, int nr_cpus, int nr_irqs)
{
	int nr_longs;

	nr_longs = nr_cpus + BITS_TO_LONGS(nr_irqs - VGIC_NR_PRIVATE_IRQS);

	b->private = kzalloc(sizeof(unsigned long) * nr_longs, GFP_KERNEL);
	if (!b->private)
		return -ENOMEM;

	b->shared = b->private + nr_cpus;

	return 0;
}

static void vgic_free_bitmap(struct vgic_bitmap *b)
{
	kfree(b->private);
	b->private = NULL;
	b->shared = NULL;
}

static u32 *vgic_bitmap_get_reg(struct vgic_bitmap *x,
				int cpuid, u32 offset)
{
	offset >>= 2;
	if (!offset)
		return (u32 *)(x->private + cpuid) + REG_OFFSET_SWIZZLE;
	else
		return (u32 *)(x->shared) + ((offset - 1) ^ REG_OFFSET_SWIZZLE);
}

static int vgic_bitmap_get_irq_val(struct vgic_bitmap *x,
				   int cpuid, int irq)
{
	if (irq < VGIC_NR_PRIVATE_IRQS)
		return test_bit(irq, x->private + cpuid);

	return test_bit(irq - VGIC_NR_PRIVATE_IRQS, x->shared);
}

static void vgic_bitmap_set_irq_val(struct vgic_bitmap *x, int cpuid,
				    int irq, int val)
{
	unsigned long *reg;

	if (irq < VGIC_NR_PRIVATE_IRQS) {
		reg = x->private + cpuid;
	} else {
		reg = x->shared;
		irq -= VGIC_NR_PRIVATE_IRQS;
	}

	if (val)
		set_bit(irq, reg);
	else
		clear_bit(irq, reg);
}

static unsigned long *vgic_bitmap_get_cpu_map(struct vgic_bitmap *x, int cpuid)
{
	return x->private + cpuid;
}

static unsigned long *vgic_bitmap_get_shared_map(struct vgic_bitmap *x)
{
	return x->shared;
}

static int vgic_init_bytemap(struct vgic_bytemap *x, int nr_cpus, int nr_irqs)
{
	int size;

	size  = nr_cpus * VGIC_NR_PRIVATE_IRQS;
	size += nr_irqs - VGIC_NR_PRIVATE_IRQS;

	x->private = kzalloc(size, GFP_KERNEL);
	if (!x->private)
		return -ENOMEM;

	x->shared = x->private + nr_cpus * VGIC_NR_PRIVATE_IRQS / sizeof(u32);
	return 0;
}

static void vgic_free_bytemap(struct vgic_bytemap *b)
{
	kfree(b->private);
	b->private = NULL;
	b->shared = NULL;
}

static u32 *vgic_bytemap_get_reg(struct vgic_bytemap *x, int cpuid, u32 offset)
{
	u32 *reg;

	if (offset < VGIC_NR_PRIVATE_IRQS) {
		reg = x->private;
		offset += cpuid * VGIC_NR_PRIVATE_IRQS;
	} else {
		reg = x->shared;
		offset -= VGIC_NR_PRIVATE_IRQS;
	}

	return reg + (offset / sizeof(u32));
}

#define VGIC_CFG_LEVEL	0
#define VGIC_CFG_EDGE	1

static bool vgic_irq_is_edge(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	int irq_val;

	irq_val = vgic_bitmap_get_irq_val(&dist->irq_cfg, vcpu->vcpu_id, irq);
	return irq_val == VGIC_CFG_EDGE;
}

static int vgic_irq_is_enabled(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	return vgic_bitmap_get_irq_val(&dist->irq_enabled, vcpu->vcpu_id, irq);
}

static int vgic_irq_is_queued(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	return vgic_bitmap_get_irq_val(&dist->irq_queued, vcpu->vcpu_id, irq);
}

static void vgic_irq_set_queued(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_queued, vcpu->vcpu_id, irq, 1);
}

static void vgic_irq_clear_queued(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_queued, vcpu->vcpu_id, irq, 0);
}

static int vgic_dist_irq_get_level(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	return vgic_bitmap_get_irq_val(&dist->irq_level, vcpu->vcpu_id, irq);
}

static void vgic_dist_irq_set_level(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_level, vcpu->vcpu_id, irq, 1);
}

static void vgic_dist_irq_clear_level(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_level, vcpu->vcpu_id, irq, 0);
}

static int vgic_dist_irq_soft_pend(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	return vgic_bitmap_get_irq_val(&dist->irq_soft_pend, vcpu->vcpu_id, irq);
}

static void vgic_dist_irq_clear_soft_pend(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_soft_pend, vcpu->vcpu_id, irq, 0);
}

static int vgic_dist_irq_is_pending(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	return vgic_bitmap_get_irq_val(&dist->irq_pending, vcpu->vcpu_id, irq);
}

static void vgic_dist_irq_set_pending(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_pending, vcpu->vcpu_id, irq, 1);
}

static void vgic_dist_irq_clear_pending(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	vgic_bitmap_set_irq_val(&dist->irq_pending, vcpu->vcpu_id, irq, 0);
}

static void vgic_cpu_irq_set(struct kvm_vcpu *vcpu, int irq)
{
	if (irq < VGIC_NR_PRIVATE_IRQS)
		set_bit(irq, vcpu->arch.vgic_cpu.pending_percpu);
	else
		set_bit(irq - VGIC_NR_PRIVATE_IRQS,
			vcpu->arch.vgic_cpu.pending_shared);
}

static void vgic_cpu_irq_clear(struct kvm_vcpu *vcpu, int irq)
{
	if (irq < VGIC_NR_PRIVATE_IRQS)
		clear_bit(irq, vcpu->arch.vgic_cpu.pending_percpu);
	else
		clear_bit(irq - VGIC_NR_PRIVATE_IRQS,
			  vcpu->arch.vgic_cpu.pending_shared);
}

static bool vgic_can_sample_irq(struct kvm_vcpu *vcpu, int irq)
{
	return vgic_irq_is_edge(vcpu, irq) || !vgic_irq_is_queued(vcpu, irq);
}

static u32 mmio_data_read(struct kvm_exit_mmio *mmio, u32 mask)
{
	return le32_to_cpu(*((u32 *)mmio->data)) & mask;
}

static void mmio_data_write(struct kvm_exit_mmio *mmio, u32 mask, u32 value)
{
	*((u32 *)mmio->data) = cpu_to_le32(value) & mask;
}

/**
 * vgic_reg_access - access vgic register
 * @mmio:   pointer to the data describing the mmio access
 * @reg:    pointer to the virtual backing of vgic distributor data
 * @offset: least significant 2 bits used for word offset
 * @mode:   ACCESS_ mode (see defines above)
 *
 * Helper to make vgic register access easier using one of the access
 * modes defined for vgic register access
 * (read,raz,write-ignored,setbit,clearbit,write)
 */
static void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg,
			    phys_addr_t offset, int mode)
{
	int word_offset = (offset & 3) * 8;
	u32 mask = (1UL << (mmio->len * 8)) - 1;
	u32 regval;

	/*
	 * Any alignment fault should have been delivered to the guest
	 * directly (ARM ARM B3.12.7 "Prioritization of aborts").
	 */

	if (reg) {
		regval = *reg;
	} else {
		BUG_ON(mode != (ACCESS_READ_RAZ | ACCESS_WRITE_IGNORED));
		regval = 0;
	}

	if (mmio->is_write) {
		u32 data = mmio_data_read(mmio, mask) << word_offset;
		switch (ACCESS_WRITE_MASK(mode)) {
		case ACCESS_WRITE_IGNORED:
			return;

		case ACCESS_WRITE_SETBIT:
			regval |= data;
			break;

		case ACCESS_WRITE_CLEARBIT:
			regval &= ~data;
			break;

		case ACCESS_WRITE_VALUE:
			regval = (regval & ~(mask << word_offset)) | data;
			break;
		}
		*reg = regval;
	} else {
		switch (ACCESS_READ_MASK(mode)) {
		case ACCESS_READ_RAZ:
			regval = 0;
			/* fall through */

		case ACCESS_READ_VALUE:
			mmio_data_write(mmio, mask, regval >> word_offset);
		}
	}
}

static bool handle_mmio_misc(struct kvm_vcpu *vcpu,
			     struct kvm_exit_mmio *mmio, phys_addr_t offset)
{
	u32 reg;
	u32 word_offset = offset & 3;

	switch (offset & ~3) {
	case 0:			/* GICD_CTLR */
		reg = vcpu->kvm->arch.vgic.enabled;
		vgic_reg_access(mmio, &reg, word_offset,
				ACCESS_READ_VALUE | ACCESS_WRITE_VALUE);
		if (mmio->is_write) {
			vcpu->kvm->arch.vgic.enabled = reg & 1;
			vgic_update_state(vcpu->kvm);
			return true;
		}
		break;

	case 4:			/* GICD_TYPER */
		reg  = (atomic_read(&vcpu->kvm->online_vcpus) - 1) << 5;
		reg |= (vcpu->kvm->arch.vgic.nr_irqs >> 5) - 1;
		vgic_reg_access(mmio, &reg, word_offset,
				ACCESS_READ_VALUE | ACCESS_WRITE_IGNORED);
		break;

	case 8:			/* GICD_IIDR */
		reg = (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
		vgic_reg_access(mmio, &reg, word_offset,
				ACCESS_READ_VALUE | ACCESS_WRITE_IGNORED);
		break;
	}

	return false;
}

static bool handle_mmio_raz_wi(struct kvm_vcpu *vcpu,
			       struct kvm_exit_mmio *mmio, phys_addr_t offset)
{
	vgic_reg_access(mmio, NULL, offset,
			ACCESS_READ_RAZ | ACCESS_WRITE_IGNORED);
	return false;
}

static bool handle_mmio_set_enable_reg(struct kvm_vcpu *vcpu,
				       struct kvm_exit_mmio *mmio,
				       phys_addr_t offset)
{
	u32 *reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_enabled,
				       vcpu->vcpu_id, offset);
	vgic_reg_access(mmio, reg, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_SETBIT);
	if (mmio->is_write) {
		vgic_update_state(vcpu->kvm);
		return true;
	}

	return false;
}

static bool handle_mmio_clear_enable_reg(struct kvm_vcpu *vcpu,
					 struct kvm_exit_mmio *mmio,
					 phys_addr_t offset)
{
	u32 *reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_enabled,
				       vcpu->vcpu_id, offset);
	vgic_reg_access(mmio, reg, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);
	if (mmio->is_write) {
		if (offset < 4) /* Force SGI enabled */
			*reg |= 0xffff;
		vgic_retire_disabled_irqs(vcpu);
		vgic_update_state(vcpu->kvm);
		return true;
	}

	return false;
}

static bool handle_mmio_set_pending_reg(struct kvm_vcpu *vcpu,
					struct kvm_exit_mmio *mmio,
					phys_addr_t offset)
{
	u32 *reg, orig;
	u32 level_mask;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	reg = vgic_bitmap_get_reg(&dist->irq_cfg, vcpu->vcpu_id, offset);
	level_mask = (~(*reg));

	/* Mark both level and edge triggered irqs as pending */
	reg = vgic_bitmap_get_reg(&dist->irq_pending, vcpu->vcpu_id, offset);
	orig = *reg;
	vgic_reg_access(mmio, reg, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_SETBIT);

	if (mmio->is_write) {
		/* Set the soft-pending flag only for level-triggered irqs */
		reg = vgic_bitmap_get_reg(&dist->irq_soft_pend,
					  vcpu->vcpu_id, offset);
		vgic_reg_access(mmio, reg, offset,
				ACCESS_READ_VALUE | ACCESS_WRITE_SETBIT);
		*reg &= level_mask;

		/* Ignore writes to SGIs */
		if (offset < 2) {
			*reg &= ~0xffff;
			*reg |= orig & 0xffff;
		}

		vgic_update_state(vcpu->kvm);
		return true;
	}

	return false;
}

static bool handle_mmio_clear_pending_reg(struct kvm_vcpu *vcpu,
					  struct kvm_exit_mmio *mmio,
					  phys_addr_t offset)
{
	u32 *level_active;
	u32 *reg, orig;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	reg = vgic_bitmap_get_reg(&dist->irq_pending, vcpu->vcpu_id, offset);
	orig = *reg;
	vgic_reg_access(mmio, reg, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);
	if (mmio->is_write) {
		/* Re-set level triggered level-active interrupts */
		level_active = vgic_bitmap_get_reg(&dist->irq_level,
					  vcpu->vcpu_id, offset);
		reg = vgic_bitmap_get_reg(&dist->irq_pending,
					  vcpu->vcpu_id, offset);
		*reg |= *level_active;

		/* Ignore writes to SGIs */
		if (offset < 2) {
			*reg &= ~0xffff;
			*reg |= orig & 0xffff;
		}

		/* Clear soft-pending flags */
		reg = vgic_bitmap_get_reg(&dist->irq_soft_pend,
					  vcpu->vcpu_id, offset);
		vgic_reg_access(mmio, reg, offset,
				ACCESS_READ_VALUE | ACCESS_WRITE_CLEARBIT);

		vgic_update_state(vcpu->kvm);
		return true;
	}

	return false;
}

static bool handle_mmio_priority_reg(struct kvm_vcpu *vcpu,
				     struct kvm_exit_mmio *mmio,
				     phys_addr_t offset)
{
	u32 *reg = vgic_bytemap_get_reg(&vcpu->kvm->arch.vgic.irq_priority,
					vcpu->vcpu_id, offset);
	vgic_reg_access(mmio, reg, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_VALUE);
	return false;
}

#define GICD_ITARGETSR_SIZE	32
#define GICD_CPUTARGETS_BITS	8
#define GICD_IRQS_PER_ITARGETSR	(GICD_ITARGETSR_SIZE / GICD_CPUTARGETS_BITS)
static u32 vgic_get_target_reg(struct kvm *kvm, int irq)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	int i;
	u32 val = 0;

	irq -= VGIC_NR_PRIVATE_IRQS;

	for (i = 0; i < GICD_IRQS_PER_ITARGETSR; i++)
		val |= 1 << (dist->irq_spi_cpu[irq + i] + i * 8);

	return val;
}

static void vgic_set_target_reg(struct kvm *kvm, u32 val, int irq)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	struct kvm_vcpu *vcpu;
	int i, c;
	unsigned long *bmap;
	u32 target;

	irq -= VGIC_NR_PRIVATE_IRQS;

	/*
	 * Pick the LSB in each byte. This ensures we target exactly
	 * one vcpu per IRQ. If the byte is null, assume we target
	 * CPU0.
	 */
	for (i = 0; i < GICD_IRQS_PER_ITARGETSR; i++) {
		int shift = i * GICD_CPUTARGETS_BITS;
		target = ffs((val >> shift) & 0xffU);
		target = target ? (target - 1) : 0;
		dist->irq_spi_cpu[irq + i] = target;
		kvm_for_each_vcpu(c, vcpu, kvm) {
			bmap = vgic_bitmap_get_shared_map(&dist->irq_spi_target[c]);
			if (c == target)
				set_bit(irq + i, bmap);
			else
				clear_bit(irq + i, bmap);
		}
	}
}

static bool handle_mmio_target_reg(struct kvm_vcpu *vcpu,
				   struct kvm_exit_mmio *mmio,
				   phys_addr_t offset)
{
	u32 reg;

	/* We treat the banked interrupts targets as read-only */
	if (offset < 32) {
		u32 roreg = 1 << vcpu->vcpu_id;
		roreg |= roreg << 8;
		roreg |= roreg << 16;

		vgic_reg_access(mmio, &roreg, offset,
				ACCESS_READ_VALUE | ACCESS_WRITE_IGNORED);
		return false;
	}

	reg = vgic_get_target_reg(vcpu->kvm, offset & ~3U);
	vgic_reg_access(mmio, &reg, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_VALUE);
	if (mmio->is_write) {
		vgic_set_target_reg(vcpu->kvm, reg, offset & ~3U);
		vgic_update_state(vcpu->kvm);
		return true;
	}

	return false;
}

static u32 vgic_cfg_expand(u16 val)
{
	u32 res = 0;
	int i;

	/*
	 * Turn a 16bit value like abcd...mnop into a 32bit word
	 * a0b0c0d0...m0n0o0p0, which is what the HW cfg register is.
	 */
	for (i = 0; i < 16; i++)
		res |= ((val >> i) & VGIC_CFG_EDGE) << (2 * i + 1);

	return res;
}

static u16 vgic_cfg_compress(u32 val)
{
	u16 res = 0;
	int i;

	/*
	 * Turn a 32bit word a0b0c0d0...m0n0o0p0 into 16bit value like
	 * abcd...mnop which is what we really care about.
	 */
	for (i = 0; i < 16; i++)
		res |= ((val >> (i * 2 + 1)) & VGIC_CFG_EDGE) << i;

	return res;
}

/*
 * The distributor uses 2 bits per IRQ for the CFG register, but the
 * LSB is always 0. As such, we only keep the upper bit, and use the
 * two above functions to compress/expand the bits
 */
static bool handle_mmio_cfg_reg(struct kvm_vcpu *vcpu,
				struct kvm_exit_mmio *mmio, phys_addr_t offset)
{
	u32 val;
	u32 *reg;

	reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_cfg,
				  vcpu->vcpu_id, offset >> 1);

	if (offset & 4)
		val = *reg >> 16;
	else
		val = *reg & 0xffff;

	val = vgic_cfg_expand(val);
	vgic_reg_access(mmio, &val, offset,
			ACCESS_READ_VALUE | ACCESS_WRITE_VALUE);
	if (mmio->is_write) {
		if (offset < 8) {
			*reg = ~0U; /* Force PPIs/SGIs to 1 */
			return false;
		}

		val = vgic_cfg_compress(val);
		if (offset & 4) {
			*reg &= 0xffff;
			*reg |= val << 16;
		} else {
			*reg &= 0xffff << 16;
			*reg |= val;
		}
	}

	return false;
}

static bool handle_mmio_sgi_reg(struct kvm_vcpu *vcpu,
				struct kvm_exit_mmio *mmio, phys_addr_t offset)
{
	u32 reg;
	vgic_reg_access(mmio, &reg, offset,
			ACCESS_READ_RAZ | ACCESS_WRITE_VALUE);
	if (mmio->is_write) {
		vgic_dispatch_sgi(vcpu, reg);
		vgic_update_state(vcpu->kvm);
		return true;
	}

	return false;
}

/**
 * vgic_unqueue_irqs - move pending IRQs from LRs to the distributor
 * @vgic_cpu: Pointer to the vgic_cpu struct holding the LRs
 *
 * Move any pending IRQs that have already been assigned to LRs back to the
 * emulated distributor state so that the complete emulated state can be read
 * from the main emulation structures without investigating the LRs.
 *
 * Note that IRQs in the active state in the LRs get their pending state moved
 * to the distributor but the active state stays in the LRs, because we don't
 * track the active state on the distributor side.
 */
static void vgic_unqueue_irqs(struct kvm_vcpu *vcpu)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	int vcpu_id = vcpu->vcpu_id;
	int i;

	for_each_set_bit(i, vgic_cpu->lr_used, vgic_cpu->nr_lr) {
		struct vgic_lr lr = vgic_get_lr(vcpu, i);

		/*
		 * There are three options for the state bits:
		 *
		 * 01: pending
		 * 10: active
		 * 11: pending and active
		 *
		 * If the LR holds only an active interrupt (not pending) then
		 * just leave it alone.
		 */
		if ((lr.state & LR_STATE_MASK) == LR_STATE_ACTIVE)
			continue;

		/*
		 * Reestablish the pending state on the distributor and the
		 * CPU interface.  It may have already been pending, but that
		 * is fine, then we are only setting a few bits that were
		 * already set.
		 */
		vgic_dist_irq_set_pending(vcpu, lr.irq);
		if (lr.irq < VGIC_NR_SGIS)
			*vgic_get_sgi_sources(dist, vcpu_id, lr.irq) |= 1 << lr.source;
		lr.state &= ~LR_STATE_PENDING;
		vgic_set_lr(vcpu, i, lr);

		/*
		 * If there's no state left on the LR (it could still be
		 * active), then the LR does not hold any useful info and can
		 * be marked as free for other use.
		 */
		if (!(lr.state & LR_STATE_MASK)) {
			vgic_retire_lr(i, lr.irq, vcpu);
			vgic_irq_clear_queued(vcpu, lr.irq);
		}

		/* Finally update the VGIC state. */
		vgic_update_state(vcpu->kvm);
	}
}

/* Handle reads of GICD_CPENDSGIRn and GICD_SPENDSGIRn */
static bool read_set_clear_sgi_pend_reg(struct kvm_vcpu *vcpu,
					struct kvm_exit_mmio *mmio,
					phys_addr_t offset)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	int sgi;
	int min_sgi = (offset & ~0x3);
	int max_sgi = min_sgi + 3;
	int vcpu_id = vcpu->vcpu_id;
	u32 reg = 0;

	/* Copy source SGIs from distributor side */
	for (sgi = min_sgi; sgi <= max_sgi; sgi++) {
		int shift = 8 * (sgi - min_sgi);
		reg |= ((u32)*vgic_get_sgi_sources(dist, vcpu_id, sgi)) << shift;
	}

	mmio_data_write(mmio, ~0, reg);
	return false;
}

static bool write_set_clear_sgi_pend_reg(struct kvm_vcpu *vcpu,
					 struct kvm_exit_mmio *mmio,
					 phys_addr_t offset, bool set)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	int sgi;
	int min_sgi = (offset & ~0x3);
	int max_sgi = min_sgi + 3;
	int vcpu_id = vcpu->vcpu_id;
	u32 reg;
	bool updated = false;

	reg = mmio_data_read(mmio, ~0);

	/* Clear pending SGIs on the distributor */
	for (sgi = min_sgi; sgi <= max_sgi; sgi++) {
		u8 mask = reg >> (8 * (sgi - min_sgi));
		u8 *src = vgic_get_sgi_sources(dist, vcpu_id, sgi);
		if (set) {
			if ((*src & mask) != mask)
				updated = true;
			*src |= mask;
		} else {
			if (*src & mask)
				updated = true;
			*src &= ~mask;
		}
	}

	if (updated)
		vgic_update_state(vcpu->kvm);

	return updated;
}

static bool handle_mmio_sgi_set(struct kvm_vcpu *vcpu,
				struct kvm_exit_mmio *mmio,
				phys_addr_t offset)
{
	if (!mmio->is_write)
		return read_set_clear_sgi_pend_reg(vcpu, mmio, offset);
	else
		return write_set_clear_sgi_pend_reg(vcpu, mmio, offset, true);
}

static bool handle_mmio_sgi_clear(struct kvm_vcpu *vcpu,
				  struct kvm_exit_mmio *mmio,
				  phys_addr_t offset)
{
	if (!mmio->is_write)
		return read_set_clear_sgi_pend_reg(vcpu, mmio, offset);
	else
		return write_set_clear_sgi_pend_reg(vcpu, mmio, offset, false);
}

/*
 * I would have liked to use the kvm_bus_io_*() API instead, but it
 * cannot cope with banked registers (only the VM pointer is passed
 * around, and we need the vcpu). One of these days, someone please
 * fix it!
 */
struct mmio_range {
	phys_addr_t base;
	unsigned long len;
	int bits_per_irq;
	bool (*handle_mmio)(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
			    phys_addr_t offset);
};

static const struct mmio_range vgic_dist_ranges[] = {
	{
		.base		= GIC_DIST_CTRL,
		.len		= 12,
		.bits_per_irq	= 0,
		.handle_mmio	= handle_mmio_misc,
	},
	{
		.base		= GIC_DIST_IGROUP,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_raz_wi,
	},
	{
		.base		= GIC_DIST_ENABLE_SET,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_set_enable_reg,
	},
	{
		.base		= GIC_DIST_ENABLE_CLEAR,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_clear_enable_reg,
	},
	{
		.base		= GIC_DIST_PENDING_SET,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_set_pending_reg,
	},
	{
		.base		= GIC_DIST_PENDING_CLEAR,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_clear_pending_reg,
	},
	{
		.base		= GIC_DIST_ACTIVE_SET,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_raz_wi,
	},
	{
		.base		= GIC_DIST_ACTIVE_CLEAR,
		.len		= VGIC_MAX_IRQS / 8,
		.bits_per_irq	= 1,
		.handle_mmio	= handle_mmio_raz_wi,
	},
	{
		.base		= GIC_DIST_PRI,
		.len		= VGIC_MAX_IRQS,
		.bits_per_irq	= 8,
		.handle_mmio	= handle_mmio_priority_reg,
	},
	{
		.base		= GIC_DIST_TARGET,
		.len		= VGIC_MAX_IRQS,
		.bits_per_irq	= 8,
		.handle_mmio	= handle_mmio_target_reg,
	},
	{
		.base		= GIC_DIST_CONFIG,
		.len		= VGIC_MAX_IRQS / 4,
		.bits_per_irq	= 2,
		.handle_mmio	= handle_mmio_cfg_reg,
	},
	{
		.base		= GIC_DIST_SOFTINT,
		.len		= 4,
		.handle_mmio	= handle_mmio_sgi_reg,
	},
	{
		.base		= GIC_DIST_SGI_PENDING_CLEAR,
		.len		= VGIC_NR_SGIS,
		.handle_mmio	= handle_mmio_sgi_clear,
	},
	{
		.base		= GIC_DIST_SGI_PENDING_SET,
		.len		= VGIC_NR_SGIS,
		.handle_mmio	= handle_mmio_sgi_set,
	},
	{}
};

static const
struct mmio_range *find_matching_range(const struct mmio_range *ranges,
				       struct kvm_exit_mmio *mmio,
				       phys_addr_t offset)
{
	const struct mmio_range *r = ranges;

	while (r->len) {
		if (offset >= r->base &&
		    (offset + mmio->len) <= (r->base + r->len))
			return r;
		r++;
	}

	return NULL;
}

static bool vgic_validate_access(const struct vgic_dist *dist,
				 const struct mmio_range *range,
				 unsigned long offset)
{
	int irq;

	if (!range->bits_per_irq)
		return true;	/* Not an irq-based access */

	irq = offset * 8 / range->bits_per_irq;
	if (irq >= dist->nr_irqs)
		return false;

	return true;
}

/**
 * vgic_handle_mmio - handle an in-kernel MMIO access
 * @vcpu:	pointer to the vcpu performing the access
 * @run:	pointer to the kvm_run structure
 * @mmio:	pointer to the data describing the access
 *
 * returns true if the MMIO access has been performed in kernel space,
 * and false if it needs to be emulated in user space.
 */
bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
		      struct kvm_exit_mmio *mmio)
{
	const struct mmio_range *range;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	unsigned long base = dist->vgic_dist_base;
	bool updated_state;
	unsigned long offset;

	if (!irqchip_in_kernel(vcpu->kvm) ||
	    mmio->phys_addr < base ||
	    (mmio->phys_addr + mmio->len) > (base + KVM_VGIC_V2_DIST_SIZE))
		return false;

	/* We don't support ldrd / strd or ldm / stm to the emulated vgic */
	if (mmio->len > 4) {
		kvm_inject_dabt(vcpu, mmio->phys_addr);
		return true;
	}

	offset = mmio->phys_addr - base;
	range = find_matching_range(vgic_dist_ranges, mmio, offset);
	if (unlikely(!range || !range->handle_mmio)) {
		pr_warn("Unhandled access %d %08llx %d\n",
			mmio->is_write, mmio->phys_addr, mmio->len);
		return false;
	}

	spin_lock(&vcpu->kvm->arch.vgic.lock);
	offset = mmio->phys_addr - range->base - base;
	if (vgic_validate_access(dist, range, offset)) {
		updated_state = range->handle_mmio(vcpu, mmio, offset);
	} else {
		vgic_reg_access(mmio, NULL, offset,
				ACCESS_READ_RAZ | ACCESS_WRITE_IGNORED);
		updated_state = false;
	}
	spin_unlock(&vcpu->kvm->arch.vgic.lock);
	kvm_prepare_mmio(run, mmio);
	kvm_handle_mmio_return(vcpu, run);

	if (updated_state)
		vgic_kick_vcpus(vcpu->kvm);

	return true;
}

static u8 *vgic_get_sgi_sources(struct vgic_dist *dist, int vcpu_id, int sgi)
{
	return dist->irq_sgi_sources + vcpu_id * VGIC_NR_SGIS + sgi;
}

static void vgic_dispatch_sgi(struct kvm_vcpu *vcpu, u32 reg)
{
	struct kvm *kvm = vcpu->kvm;
	struct vgic_dist *dist = &kvm->arch.vgic;
	int nrcpus = atomic_read(&kvm->online_vcpus);
	u8 target_cpus;
	int sgi, mode, c, vcpu_id;

	vcpu_id = vcpu->vcpu_id;

	sgi = reg & 0xf;
	target_cpus = (reg >> 16) & 0xff;
	mode = (reg >> 24) & 3;

	switch (mode) {
	case 0:
		if (!target_cpus)
			return;
		break;

	case 1:
		target_cpus = ((1 << nrcpus) - 1) & ~(1 << vcpu_id) & 0xff;
		break;

	case 2:
		target_cpus = 1 << vcpu_id;
		break;
	}

	kvm_for_each_vcpu(c, vcpu, kvm) {
		if (target_cpus & 1) {
			/* Flag the SGI as pending */
			vgic_dist_irq_set_pending(vcpu, sgi);
			*vgic_get_sgi_sources(dist, c, sgi) |= 1 << vcpu_id;
			kvm_debug("SGI%d from CPU%d to CPU%d\n", sgi, vcpu_id, c);
		}

		target_cpus >>= 1;
	}
}

static int vgic_nr_shared_irqs(struct vgic_dist *dist)
{
	return dist->nr_irqs - VGIC_NR_PRIVATE_IRQS;
}

static int compute_pending_for_cpu(struct kvm_vcpu *vcpu)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	unsigned long *pending, *enabled, *pend_percpu, *pend_shared;
	unsigned long pending_private, pending_shared;
	int nr_shared = vgic_nr_shared_irqs(dist);
	int vcpu_id;

	vcpu_id = vcpu->vcpu_id;
	pend_percpu = vcpu->arch.vgic_cpu.pending_percpu;
	pend_shared = vcpu->arch.vgic_cpu.pending_shared;

	pending = vgic_bitmap_get_cpu_map(&dist->irq_pending, vcpu_id);
	enabled = vgic_bitmap_get_cpu_map(&dist->irq_enabled, vcpu_id);
	bitmap_and(pend_percpu, pending, enabled, VGIC_NR_PRIVATE_IRQS);

	pending = vgic_bitmap_get_shared_map(&dist->irq_pending);
	enabled = vgic_bitmap_get_shared_map(&dist->irq_enabled);
	bitmap_and(pend_shared, pending, enabled, nr_shared);
	bitmap_and(pend_shared, pend_shared,
		   vgic_bitmap_get_shared_map(&dist->irq_spi_target[vcpu_id]),
		   nr_shared);

	pending_private = find_first_bit(pend_percpu, VGIC_NR_PRIVATE_IRQS);
	pending_shared = find_first_bit(pend_shared, nr_shared);
	return (pending_private < VGIC_NR_PRIVATE_IRQS ||
		pending_shared < vgic_nr_shared_irqs(dist));
}

/*
 * Update the interrupt state and determine which CPUs have pending
 * interrupts. Must be called with distributor lock held.
 */
static void vgic_update_state(struct kvm *kvm)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	struct kvm_vcpu *vcpu;
	int c;

	if (!dist->enabled) {
		set_bit(0, dist->irq_pending_on_cpu);
		return;
	}

	kvm_for_each_vcpu(c, vcpu, kvm) {
		if (compute_pending_for_cpu(vcpu)) {
			pr_debug("CPU%d has pending interrupts\n", c);
			set_bit(c, dist->irq_pending_on_cpu);
		}
	}
}

static struct vgic_lr vgic_get_lr(const struct kvm_vcpu *vcpu, int lr)
{
	return vgic_ops->get_lr(vcpu, lr);
}

static void vgic_set_lr(struct kvm_vcpu *vcpu, int lr,
			       struct vgic_lr vlr)
{
	vgic_ops->set_lr(vcpu, lr, vlr);
}

static void vgic_sync_lr_elrsr(struct kvm_vcpu *vcpu, int lr,
			       struct vgic_lr vlr)
{
	vgic_ops->sync_lr_elrsr(vcpu, lr, vlr);
}

static inline u64 vgic_get_elrsr(struct kvm_vcpu *vcpu)
{
	return vgic_ops->get_elrsr(vcpu);
}

static inline u64 vgic_get_eisr(struct kvm_vcpu *vcpu)
{
	return vgic_ops->get_eisr(vcpu);
}

static inline u32 vgic_get_interrupt_status(struct kvm_vcpu *vcpu)
{
	return vgic_ops->get_interrupt_status(vcpu);
}

static inline void vgic_enable_underflow(struct kvm_vcpu *vcpu)
{
	vgic_ops->enable_underflow(vcpu);
}

static inline void vgic_disable_underflow(struct kvm_vcpu *vcpu)
{
	vgic_ops->disable_underflow(vcpu);
}

static inline void vgic_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
{
	vgic_ops->get_vmcr(vcpu, vmcr);
}

static void vgic_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcr)
{
	vgic_ops->set_vmcr(vcpu, vmcr);
}

static inline void vgic_enable(struct kvm_vcpu *vcpu)
{
	vgic_ops->enable(vcpu);
}

static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	struct vgic_lr vlr = vgic_get_lr(vcpu, lr_nr);

	vlr.state = 0;
	vgic_set_lr(vcpu, lr_nr, vlr);
	clear_bit(lr_nr, vgic_cpu->lr_used);
	vgic_cpu->vgic_irq_lr_map[irq] = LR_EMPTY;
}

/*
 * An interrupt may have been disabled after being made pending on the
 * CPU interface (the classic case is a timer running while we're
 * rebooting the guest - the interrupt would kick as soon as the CPU
 * interface gets enabled, with deadly consequences).
 *
 * The solution is to examine already active LRs, and check the
 * interrupt is still enabled. If not, just retire it.
 */
static void vgic_retire_disabled_irqs(struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	int lr;

	for_each_set_bit(lr, vgic_cpu->lr_used, vgic->nr_lr) {
		struct vgic_lr vlr = vgic_get_lr(vcpu, lr);

		if (!vgic_irq_is_enabled(vcpu, vlr.irq)) {
			vgic_retire_lr(lr, vlr.irq, vcpu);
			if (vgic_irq_is_queued(vcpu, vlr.irq))
				vgic_irq_clear_queued(vcpu, vlr.irq);
		}
	}
}

/*
 * Queue an interrupt to a CPU virtual interface. Return true on success,
 * or false if it wasn't possible to queue it.
 */
static bool vgic_queue_irq(struct kvm_vcpu *vcpu, u8 sgi_source_id, int irq)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	struct vgic_lr vlr;
	int lr;

	/* Sanitize the input... */
	BUG_ON(sgi_source_id & ~7);
	BUG_ON(sgi_source_id && irq >= VGIC_NR_SGIS);
	BUG_ON(irq >= dist->nr_irqs);

	kvm_debug("Queue IRQ%d\n", irq);

	lr = vgic_cpu->vgic_irq_lr_map[irq];

	/* Do we have an active interrupt for the same CPUID? */
	if (lr != LR_EMPTY) {
		vlr = vgic_get_lr(vcpu, lr);
		if (vlr.source == sgi_source_id) {
			kvm_debug("LR%d piggyback for IRQ%d\n", lr, vlr.irq);
			BUG_ON(!test_bit(lr, vgic_cpu->lr_used));
			vlr.state |= LR_STATE_PENDING;
			vgic_set_lr(vcpu, lr, vlr);
			return true;
		}
	}

	/* Try to use another LR for this interrupt */
	lr = find_first_zero_bit((unsigned long *)vgic_cpu->lr_used,
			       vgic->nr_lr);
	if (lr >= vgic->nr_lr)
		return false;

	kvm_debug("LR%d allocated for IRQ%d %x\n", lr, irq, sgi_source_id);
	vgic_cpu->vgic_irq_lr_map[irq] = lr;
	set_bit(lr, vgic_cpu->lr_used);

	vlr.irq = irq;
	vlr.source = sgi_source_id;
	vlr.state = LR_STATE_PENDING;
	if (!vgic_irq_is_edge(vcpu, irq))
		vlr.state |= LR_EOI_INT;

	vgic_set_lr(vcpu, lr, vlr);

	return true;
}

static bool vgic_queue_sgi(struct kvm_vcpu *vcpu, int irq)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	unsigned long sources;
	int vcpu_id = vcpu->vcpu_id;
	int c;

	sources = *vgic_get_sgi_sources(dist, vcpu_id, irq);

	for_each_set_bit(c, &sources, dist->nr_cpus) {
		if (vgic_queue_irq(vcpu, c, irq))
			clear_bit(c, &sources);
	}

	*vgic_get_sgi_sources(dist, vcpu_id, irq) = sources;

	/*
	 * If the sources bitmap has been cleared it means that we
	 * could queue all the SGIs onto link registers (see the
	 * clear_bit above), and therefore we are done with them in
	 * our emulated gic and can get rid of them.
	 */
	if (!sources) {
		vgic_dist_irq_clear_pending(vcpu, irq);
		vgic_cpu_irq_clear(vcpu, irq);
		return true;
	}

	return false;
}

static bool vgic_queue_hwirq(struct kvm_vcpu *vcpu, int irq)
{
	if (!vgic_can_sample_irq(vcpu, irq))
		return true; /* level interrupt, already queued */

	if (vgic_queue_irq(vcpu, 0, irq)) {
		if (vgic_irq_is_edge(vcpu, irq)) {
			vgic_dist_irq_clear_pending(vcpu, irq);
			vgic_cpu_irq_clear(vcpu, irq);
		} else {
			vgic_irq_set_queued(vcpu, irq);
		}

		return true;
	}

	return false;
}

/*
 * Fill the list registers with pending interrupts before running the
 * guest.
 */
static void __kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	int i, vcpu_id;
	int overflow = 0;

	vcpu_id = vcpu->vcpu_id;

	/*
	 * We may not have any pending interrupt, or the interrupts
	 * may have been serviced from another vcpu. In all cases,
	 * move along.
	 */
	if (!kvm_vgic_vcpu_pending_irq(vcpu)) {
		pr_debug("CPU%d has no pending interrupt\n", vcpu_id);
		goto epilog;
	}

	/* SGIs */
	for_each_set_bit(i, vgic_cpu->pending_percpu, VGIC_NR_SGIS) {
		if (!vgic_queue_sgi(vcpu, i))
			overflow = 1;
	}

	/* PPIs */
	for_each_set_bit_from(i, vgic_cpu->pending_percpu, VGIC_NR_PRIVATE_IRQS) {
		if (!vgic_queue_hwirq(vcpu, i))
			overflow = 1;
	}

	/* SPIs */
	for_each_set_bit(i, vgic_cpu->pending_shared, vgic_nr_shared_irqs(dist)) {
		if (!vgic_queue_hwirq(vcpu, i + VGIC_NR_PRIVATE_IRQS))
			overflow = 1;
	}

epilog:
	if (overflow) {
		vgic_enable_underflow(vcpu);
	} else {
		vgic_disable_underflow(vcpu);
		/*
		 * We're about to run this VCPU, and we've consumed
		 * everything the distributor had in store for
		 * us. Claim we don't have anything pending. We'll
		 * adjust that if needed while exiting.
		 */
		clear_bit(vcpu_id, dist->irq_pending_on_cpu);
	}
}

static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
{
	u32 status = vgic_get_interrupt_status(vcpu);
	bool level_pending = false;

	kvm_debug("STATUS = %08x\n", status);

	if (status & INT_STATUS_EOI) {
		/*
		 * Some level interrupts have been EOIed. Clear their
		 * active bit.
		 */
		u64 eisr = vgic_get_eisr(vcpu);
		unsigned long *eisr_ptr = (unsigned long *)&eisr;
		int lr;

		for_each_set_bit(lr, eisr_ptr, vgic->nr_lr) {
			struct vgic_lr vlr = vgic_get_lr(vcpu, lr);
			WARN_ON(vgic_irq_is_edge(vcpu, vlr.irq));

			vgic_irq_clear_queued(vcpu, vlr.irq);
			WARN_ON(vlr.state & LR_STATE_MASK);
			vlr.state = 0;
			vgic_set_lr(vcpu, lr, vlr);

			/*
			 * If the IRQ was EOIed it was also ACKed and we we
			 * therefore assume we can clear the soft pending
			 * state (should it had been set) for this interrupt.
			 *
			 * Note: if the IRQ soft pending state was set after
			 * the IRQ was acked, it actually shouldn't be
			 * cleared, but we have no way of knowing that unless
			 * we start trapping ACKs when the soft-pending state
			 * is set.
			 */
			vgic_dist_irq_clear_soft_pend(vcpu, vlr.irq);

			/* Any additional pending interrupt? */
			if (vgic_dist_irq_get_level(vcpu, vlr.irq)) {
				vgic_cpu_irq_set(vcpu, vlr.irq);
				level_pending = true;
			} else {
				vgic_dist_irq_clear_pending(vcpu, vlr.irq);
				vgic_cpu_irq_clear(vcpu, vlr.irq);
			}

			/*
			 * Despite being EOIed, the LR may not have
			 * been marked as empty.
			 */
			vgic_sync_lr_elrsr(vcpu, lr, vlr);
		}
	}

	if (status & INT_STATUS_UNDERFLOW)
		vgic_disable_underflow(vcpu);

	return level_pending;
}

/*
 * Sync back the VGIC state after a guest run. The distributor lock is
 * needed so we don't get preempted in the middle of the state processing.
 */
static void __kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	u64 elrsr;
	unsigned long *elrsr_ptr;
	int lr, pending;
	bool level_pending;

	level_pending = vgic_process_maintenance(vcpu);
	elrsr = vgic_get_elrsr(vcpu);
	elrsr_ptr = (unsigned long *)&elrsr;

	/* Clear mappings for empty LRs */
	for_each_set_bit(lr, elrsr_ptr, vgic->nr_lr) {
		struct vgic_lr vlr;

		if (!test_and_clear_bit(lr, vgic_cpu->lr_used))
			continue;

		vlr = vgic_get_lr(vcpu, lr);

		BUG_ON(vlr.irq >= dist->nr_irqs);
		vgic_cpu->vgic_irq_lr_map[vlr.irq] = LR_EMPTY;
	}

	/* Check if we still have something up our sleeve... */
	pending = find_first_zero_bit(elrsr_ptr, vgic->nr_lr);
	if (level_pending || pending < vgic->nr_lr)
		set_bit(vcpu->vcpu_id, dist->irq_pending_on_cpu);
}

void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	if (!irqchip_in_kernel(vcpu->kvm))
		return;

	spin_lock(&dist->lock);
	__kvm_vgic_flush_hwstate(vcpu);
	spin_unlock(&dist->lock);
}

void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	if (!irqchip_in_kernel(vcpu->kvm))
		return;

	spin_lock(&dist->lock);
	__kvm_vgic_sync_hwstate(vcpu);
	spin_unlock(&dist->lock);
}

int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
{
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;

	if (!irqchip_in_kernel(vcpu->kvm))
		return 0;

	return test_bit(vcpu->vcpu_id, dist->irq_pending_on_cpu);
}

static void vgic_kick_vcpus(struct kvm *kvm)
{
	struct kvm_vcpu *vcpu;
	int c;

	/*
	 * We've injected an interrupt, time to find out who deserves
	 * a good kick...
	 */
	kvm_for_each_vcpu(c, vcpu, kvm) {
		if (kvm_vgic_vcpu_pending_irq(vcpu))
			kvm_vcpu_kick(vcpu);
	}
}

static int vgic_validate_injection(struct kvm_vcpu *vcpu, int irq, int level)
{
	int edge_triggered = vgic_irq_is_edge(vcpu, irq);

	/*
	 * Only inject an interrupt if:
	 * - edge triggered and we have a rising edge
	 * - level triggered and we change level
	 */
	if (edge_triggered) {
		int state = vgic_dist_irq_is_pending(vcpu, irq);
		return level > state;
	} else {
		int state = vgic_dist_irq_get_level(vcpu, irq);
		return level != state;
	}
}

static bool vgic_update_irq_pending(struct kvm *kvm, int cpuid,
				  unsigned int irq_num, bool level)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	struct kvm_vcpu *vcpu;
	int edge_triggered, level_triggered;
	int enabled;
	bool ret = true;

	spin_lock(&dist->lock);

	vcpu = kvm_get_vcpu(kvm, cpuid);
	edge_triggered = vgic_irq_is_edge(vcpu, irq_num);
	level_triggered = !edge_triggered;

	if (!vgic_validate_injection(vcpu, irq_num, level)) {
		ret = false;
		goto out;
	}

	if (irq_num >= VGIC_NR_PRIVATE_IRQS) {
		cpuid = dist->irq_spi_cpu[irq_num - VGIC_NR_PRIVATE_IRQS];
		vcpu = kvm_get_vcpu(kvm, cpuid);
	}

	kvm_debug("Inject IRQ%d level %d CPU%d\n", irq_num, level, cpuid);

	if (level) {
		if (level_triggered)
			vgic_dist_irq_set_level(vcpu, irq_num);
		vgic_dist_irq_set_pending(vcpu, irq_num);
	} else {
		if (level_triggered) {
			vgic_dist_irq_clear_level(vcpu, irq_num);
			if (!vgic_dist_irq_soft_pend(vcpu, irq_num))
				vgic_dist_irq_clear_pending(vcpu, irq_num);
		} else {
			vgic_dist_irq_clear_pending(vcpu, irq_num);
		}
	}

	enabled = vgic_irq_is_enabled(vcpu, irq_num);

	if (!enabled) {
		ret = false;
		goto out;
	}

	if (!vgic_can_sample_irq(vcpu, irq_num)) {
		/*
		 * Level interrupt in progress, will be picked up
		 * when EOId.
		 */
		ret = false;
		goto out;
	}

	if (level) {
		vgic_cpu_irq_set(vcpu, irq_num);
		set_bit(cpuid, dist->irq_pending_on_cpu);
	}

out:
	spin_unlock(&dist->lock);

	return ret;
}

/**
 * kvm_vgic_inject_irq - Inject an IRQ from a device to the vgic
 * @kvm:     The VM structure pointer
 * @cpuid:   The CPU for PPIs
 * @irq_num: The IRQ number that is assigned to the device
 * @level:   Edge-triggered:  true:  to trigger the interrupt
 *			      false: to ignore the call
 *	     Level-sensitive  true:  activates an interrupt
 *			      false: deactivates an interrupt
 *
 * The GIC is not concerned with devices being active-LOW or active-HIGH for
 * level-sensitive interrupts.  You can think of the level parameter as 1
 * being HIGH and 0 being LOW and all devices being active-HIGH.
 */
int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
			bool level)
{
	if (likely(vgic_initialized(kvm)) &&
	    vgic_update_irq_pending(kvm, cpuid, irq_num, level))
		vgic_kick_vcpus(kvm);

	return 0;
}

static irqreturn_t vgic_maintenance_handler(int irq, void *data)
{
	/*
	 * We cannot rely on the vgic maintenance interrupt to be
	 * delivered synchronously. This means we can only use it to
	 * exit the VM, and we perform the handling of EOIed
	 * interrupts on the exit path (see vgic_process_maintenance).
	 */
	return IRQ_HANDLED;
}

void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;

	kfree(vgic_cpu->pending_shared);
	kfree(vgic_cpu->vgic_irq_lr_map);
	vgic_cpu->pending_shared = NULL;
	vgic_cpu->vgic_irq_lr_map = NULL;
}

static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;

	int sz = (nr_irqs - VGIC_NR_PRIVATE_IRQS) / 8;
	vgic_cpu->pending_shared = kzalloc(sz, GFP_KERNEL);
	vgic_cpu->vgic_irq_lr_map = kzalloc(nr_irqs, GFP_KERNEL);

	if (!vgic_cpu->pending_shared || !vgic_cpu->vgic_irq_lr_map) {
		kvm_vgic_vcpu_destroy(vcpu);
		return -ENOMEM;
	}

	return 0;
}

/**
 * kvm_vgic_vcpu_init - Initialize per-vcpu VGIC state
 * @vcpu: pointer to the vcpu struct
 *
 * Initialize the vgic_cpu struct and vgic_dist struct fields pertaining to
 * this vcpu and enable the VGIC for this VCPU
 */
static void kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
	int i;

	for (i = 0; i < dist->nr_irqs; i++) {
		if (i < VGIC_NR_PPIS)
			vgic_bitmap_set_irq_val(&dist->irq_enabled,
						vcpu->vcpu_id, i, 1);
		if (i < VGIC_NR_PRIVATE_IRQS)
			vgic_bitmap_set_irq_val(&dist->irq_cfg,
						vcpu->vcpu_id, i, VGIC_CFG_EDGE);

		vgic_cpu->vgic_irq_lr_map[i] = LR_EMPTY;
	}

	/*
	 * Store the number of LRs per vcpu, so we don't have to go
	 * all the way to the distributor structure to find out. Only
	 * assembly code should use this one.
	 */
	vgic_cpu->nr_lr = vgic->nr_lr;

	vgic_enable(vcpu);
}

void kvm_vgic_destroy(struct kvm *kvm)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	struct kvm_vcpu *vcpu;
	int i;

	kvm_for_each_vcpu(i, vcpu, kvm)
		kvm_vgic_vcpu_destroy(vcpu);

	vgic_free_bitmap(&dist->irq_enabled);
	vgic_free_bitmap(&dist->irq_level);
	vgic_free_bitmap(&dist->irq_pending);
	vgic_free_bitmap(&dist->irq_soft_pend);
	vgic_free_bitmap(&dist->irq_queued);
	vgic_free_bitmap(&dist->irq_cfg);
	vgic_free_bytemap(&dist->irq_priority);
	if (dist->irq_spi_target) {
		for (i = 0; i < dist->nr_cpus; i++)
			vgic_free_bitmap(&dist->irq_spi_target[i]);
	}
	kfree(dist->irq_sgi_sources);
	kfree(dist->irq_spi_cpu);
	kfree(dist->irq_spi_target);
	kfree(dist->irq_pending_on_cpu);
	dist->irq_sgi_sources = NULL;
	dist->irq_spi_cpu = NULL;
	dist->irq_spi_target = NULL;
	dist->irq_pending_on_cpu = NULL;
}

/*
 * Allocate and initialize the various data structures. Must be called
 * with kvm->lock held!
 */
static int vgic_init_maps(struct kvm *kvm)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	struct kvm_vcpu *vcpu;
	int nr_cpus, nr_irqs;
	int ret, i;

	if (dist->nr_cpus)	/* Already allocated */
		return 0;

	nr_cpus = dist->nr_cpus = atomic_read(&kvm->online_vcpus);
	if (!nr_cpus)		/* No vcpus? Can't be good... */
		return -EINVAL;

	/*
	 * If nobody configured the number of interrupts, use the
	 * legacy one.
	 */
	if (!dist->nr_irqs)
		dist->nr_irqs = VGIC_NR_IRQS_LEGACY;

	nr_irqs = dist->nr_irqs;

	ret  = vgic_init_bitmap(&dist->irq_enabled, nr_cpus, nr_irqs);
	ret |= vgic_init_bitmap(&dist->irq_level, nr_cpus, nr_irqs);
	ret |= vgic_init_bitmap(&dist->irq_pending, nr_cpus, nr_irqs);
	ret |= vgic_init_bitmap(&dist->irq_soft_pend, nr_cpus, nr_irqs);
	ret |= vgic_init_bitmap(&dist->irq_queued, nr_cpus, nr_irqs);
	ret |= vgic_init_bitmap(&dist->irq_cfg, nr_cpus, nr_irqs);
	ret |= vgic_init_bytemap(&dist->irq_priority, nr_cpus, nr_irqs);

	if (ret)
		goto out;

	dist->irq_sgi_sources = kzalloc(nr_cpus * VGIC_NR_SGIS, GFP_KERNEL);
	dist->irq_spi_cpu = kzalloc(nr_irqs - VGIC_NR_PRIVATE_IRQS, GFP_KERNEL);
	dist->irq_spi_target = kzalloc(sizeof(*dist->irq_spi_target) * nr_cpus,
				       GFP_KERNEL);
	dist->irq_pending_on_cpu = kzalloc(BITS_TO_LONGS(nr_cpus) * sizeof(long),
					   GFP_KERNEL);
	if (!dist->irq_sgi_sources ||
	    !dist->irq_spi_cpu ||
	    !dist->irq_spi_target ||
	    !dist->irq_pending_on_cpu) {
		ret = -ENOMEM;
		goto out;
	}

	for (i = 0; i < nr_cpus; i++)
		ret |= vgic_init_bitmap(&dist->irq_spi_target[i],
					nr_cpus, nr_irqs);

	if (ret)
		goto out;

	kvm_for_each_vcpu(i, vcpu, kvm) {
		ret = vgic_vcpu_init_maps(vcpu, nr_irqs);
		if (ret) {
			kvm_err("VGIC: Failed to allocate vcpu memory\n");
			break;
		}
	}

	for (i = VGIC_NR_PRIVATE_IRQS; i < dist->nr_irqs; i += 4)
		vgic_set_target_reg(kvm, 0, i);

out:
	if (ret)
		kvm_vgic_destroy(kvm);

	return ret;
}

/**
 * kvm_vgic_init - Initialize global VGIC state before running any VCPUs
 * @kvm: pointer to the kvm struct
 *
 * Map the virtual CPU interface into the VM before running any VCPUs.  We
 * can't do this at creation time, because user space must first set the
 * virtual CPU interface address in the guest physical address space.  Also
 * initialize the ITARGETSRn regs to 0 on the emulated distributor.
 */
int kvm_vgic_init(struct kvm *kvm)
{
	struct kvm_vcpu *vcpu;
	int ret = 0, i;

	if (!irqchip_in_kernel(kvm))
		return 0;

	mutex_lock(&kvm->lock);

	if (vgic_initialized(kvm))
		goto out;

	if (IS_VGIC_ADDR_UNDEF(kvm->arch.vgic.vgic_dist_base) ||
	    IS_VGIC_ADDR_UNDEF(kvm->arch.vgic.vgic_cpu_base)) {
		kvm_err("Need to set vgic cpu and dist addresses first\n");
		ret = -ENXIO;
		goto out;
	}

	ret = vgic_init_maps(kvm);
	if (ret) {
		kvm_err("Unable to allocate maps\n");
		goto out;
	}

	ret = kvm_phys_addr_ioremap(kvm, kvm->arch.vgic.vgic_cpu_base,
				    vgic->vcpu_base, KVM_VGIC_V2_CPU_SIZE,
				    true);
	if (ret) {
		kvm_err("Unable to remap VGIC CPU to VCPU\n");
		goto out;
	}

	kvm_for_each_vcpu(i, vcpu, kvm)
		kvm_vgic_vcpu_init(vcpu);

	kvm->arch.vgic.ready = true;
out:
	if (ret)
		kvm_vgic_destroy(kvm);
	mutex_unlock(&kvm->lock);
	return ret;
}

int kvm_vgic_create(struct kvm *kvm)
{
	int i, vcpu_lock_idx = -1, ret = 0;
	struct kvm_vcpu *vcpu;

	mutex_lock(&kvm->lock);

	if (kvm->arch.vgic.vctrl_base) {
		ret = -EEXIST;
		goto out;
	}

	/*
	 * Any time a vcpu is run, vcpu_load is called which tries to grab the
	 * vcpu->mutex.  By grabbing the vcpu->mutex of all VCPUs we ensure
	 * that no other VCPUs are run while we create the vgic.
	 */
	kvm_for_each_vcpu(i, vcpu, kvm) {
		if (!mutex_trylock(&vcpu->mutex))
			goto out_unlock;
		vcpu_lock_idx = i;
	}

	kvm_for_each_vcpu(i, vcpu, kvm) {
		if (vcpu->arch.has_run_once) {
			ret = -EBUSY;
			goto out_unlock;
		}
	}

	spin_lock_init(&kvm->arch.vgic.lock);
	kvm->arch.vgic.in_kernel = true;
	kvm->arch.vgic.vctrl_base = vgic->vctrl_base;
	kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
	kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;

out_unlock:
	for (; vcpu_lock_idx >= 0; vcpu_lock_idx--) {
		vcpu = kvm_get_vcpu(kvm, vcpu_lock_idx);
		mutex_unlock(&vcpu->mutex);
	}

out:
	mutex_unlock(&kvm->lock);
	return ret;
}

static int vgic_ioaddr_overlap(struct kvm *kvm)
{
	phys_addr_t dist = kvm->arch.vgic.vgic_dist_base;
	phys_addr_t cpu = kvm->arch.vgic.vgic_cpu_base;

	if (IS_VGIC_ADDR_UNDEF(dist) || IS_VGIC_ADDR_UNDEF(cpu))
		return 0;
	if ((dist <= cpu && dist + KVM_VGIC_V2_DIST_SIZE > cpu) ||
	    (cpu <= dist && cpu + KVM_VGIC_V2_CPU_SIZE > dist))
		return -EBUSY;
	return 0;
}

static int vgic_ioaddr_assign(struct kvm *kvm, phys_addr_t *ioaddr,
			      phys_addr_t addr, phys_addr_t size)
{
	int ret;

	if (addr & ~KVM_PHYS_MASK)
		return -E2BIG;

	if (addr & (SZ_4K - 1))
		return -EINVAL;

	if (!IS_VGIC_ADDR_UNDEF(*ioaddr))
		return -EEXIST;
	if (addr + size < addr)
		return -EINVAL;

	*ioaddr = addr;
	ret = vgic_ioaddr_overlap(kvm);
	if (ret)
		*ioaddr = VGIC_ADDR_UNDEF;

	return ret;
}

/**
 * kvm_vgic_addr - set or get vgic VM base addresses
 * @kvm:   pointer to the vm struct
 * @type:  the VGIC addr type, one of KVM_VGIC_V2_ADDR_TYPE_XXX
 * @addr:  pointer to address value
 * @write: if true set the address in the VM address space, if false read the
 *          address
 *
 * Set or get the vgic base addresses for the distributor and the virtual CPU
 * interface in the VM physical address space.  These addresses are properties
 * of the emulated core/SoC and therefore user space initially knows this
 * information.
 */
int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
{
	int r = 0;
	struct vgic_dist *vgic = &kvm->arch.vgic;

	mutex_lock(&kvm->lock);
	switch (type) {
	case KVM_VGIC_V2_ADDR_TYPE_DIST:
		if (write) {
			r = vgic_ioaddr_assign(kvm, &vgic->vgic_dist_base,
					       *addr, KVM_VGIC_V2_DIST_SIZE);
		} else {
			*addr = vgic->vgic_dist_base;
		}
		break;
	case KVM_VGIC_V2_ADDR_TYPE_CPU:
		if (write) {
			r = vgic_ioaddr_assign(kvm, &vgic->vgic_cpu_base,
					       *addr, KVM_VGIC_V2_CPU_SIZE);
		} else {
			*addr = vgic->vgic_cpu_base;
		}
		break;
	default:
		r = -ENODEV;
	}

	mutex_unlock(&kvm->lock);
	return r;
}

static bool handle_cpu_mmio_misc(struct kvm_vcpu *vcpu,
				 struct kvm_exit_mmio *mmio, phys_addr_t offset)
{
	bool updated = false;
	struct vgic_vmcr vmcr;
	u32 *vmcr_field;
	u32 reg;

	vgic_get_vmcr(vcpu, &vmcr);

	switch (offset & ~0x3) {
	case GIC_CPU_CTRL:
		vmcr_field = &vmcr.ctlr;
		break;
	case GIC_CPU_PRIMASK:
		vmcr_field = &vmcr.pmr;
		break;
	case GIC_CPU_BINPOINT:
		vmcr_field = &vmcr.bpr;
		break;
	case GIC_CPU_ALIAS_BINPOINT:
		vmcr_field = &vmcr.abpr;
		break;
	default:
		BUG();
	}

	if (!mmio->is_write) {
		reg = *vmcr_field;
		mmio_data_write(mmio, ~0, reg);
	} else {
		reg = mmio_data_read(mmio, ~0);
		if (reg != *vmcr_field) {
			*vmcr_field = reg;
			vgic_set_vmcr(vcpu, &vmcr);
			updated = true;
		}
	}
	return updated;
}

static bool handle_mmio_abpr(struct kvm_vcpu *vcpu,
			     struct kvm_exit_mmio *mmio, phys_addr_t offset)
{
	return handle_cpu_mmio_misc(vcpu, mmio, GIC_CPU_ALIAS_BINPOINT);
}

static bool handle_cpu_mmio_ident(struct kvm_vcpu *vcpu,
				  struct kvm_exit_mmio *mmio,
				  phys_addr_t offset)
{
	u32 reg;

	if (mmio->is_write)
		return false;

	/* GICC_IIDR */
	reg = (PRODUCT_ID_KVM << 20) |
	      (GICC_ARCH_VERSION_V2 << 16) |
	      (IMPLEMENTER_ARM << 0);
	mmio_data_write(mmio, ~0, reg);
	return false;
}

/*
 * CPU Interface Register accesses - these are not accessed by the VM, but by
 * user space for saving and restoring VGIC state.
 */
static const struct mmio_range vgic_cpu_ranges[] = {
	{
		.base		= GIC_CPU_CTRL,
		.len		= 12,
		.handle_mmio	= handle_cpu_mmio_misc,
	},
	{
		.base		= GIC_CPU_ALIAS_BINPOINT,
		.len		= 4,
		.handle_mmio	= handle_mmio_abpr,
	},
	{
		.base		= GIC_CPU_ACTIVEPRIO,
		.len		= 16,
		.handle_mmio	= handle_mmio_raz_wi,
	},
	{
		.base		= GIC_CPU_IDENT,
		.len		= 4,
		.handle_mmio	= handle_cpu_mmio_ident,
	},
};

static int vgic_attr_regs_access(struct kvm_device *dev,
				 struct kvm_device_attr *attr,
				 u32 *reg, bool is_write)
{
	const struct mmio_range *r = NULL, *ranges;
	phys_addr_t offset;
	int ret, cpuid, c;
	struct kvm_vcpu *vcpu, *tmp_vcpu;
	struct vgic_dist *vgic;
	struct kvm_exit_mmio mmio;

	offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
	cpuid = (attr->attr & KVM_DEV_ARM_VGIC_CPUID_MASK) >>
		KVM_DEV_ARM_VGIC_CPUID_SHIFT;

	mutex_lock(&dev->kvm->lock);

	ret = vgic_init_maps(dev->kvm);
	if (ret)
		goto out;

	if (cpuid >= atomic_read(&dev->kvm->online_vcpus)) {
		ret = -EINVAL;
		goto out;
	}

	vcpu = kvm_get_vcpu(dev->kvm, cpuid);
	vgic = &dev->kvm->arch.vgic;

	mmio.len = 4;
	mmio.is_write = is_write;
	if (is_write)
		mmio_data_write(&mmio, ~0, *reg);
	switch (attr->group) {
	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
		mmio.phys_addr = vgic->vgic_dist_base + offset;
		ranges = vgic_dist_ranges;
		break;
	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
		mmio.phys_addr = vgic->vgic_cpu_base + offset;
		ranges = vgic_cpu_ranges;
		break;
	default:
		BUG();
	}
	r = find_matching_range(ranges, &mmio, offset);

	if (unlikely(!r || !r->handle_mmio)) {
		ret = -ENXIO;
		goto out;
	}


	spin_lock(&vgic->lock);

	/*
	 * Ensure that no other VCPU is running by checking the vcpu->cpu
	 * field.  If no other VPCUs are running we can safely access the VGIC
	 * state, because even if another VPU is run after this point, that
	 * VCPU will not touch the vgic state, because it will block on
	 * getting the vgic->lock in kvm_vgic_sync_hwstate().
	 */
	kvm_for_each_vcpu(c, tmp_vcpu, dev->kvm) {
		if (unlikely(tmp_vcpu->cpu != -1)) {
			ret = -EBUSY;
			goto out_vgic_unlock;
		}
	}

	/*
	 * Move all pending IRQs from the LRs on all VCPUs so the pending
	 * state can be properly represented in the register state accessible
	 * through this API.
	 */
	kvm_for_each_vcpu(c, tmp_vcpu, dev->kvm)
		vgic_unqueue_irqs(tmp_vcpu);

	offset -= r->base;
	r->handle_mmio(vcpu, &mmio, offset);

	if (!is_write)
		*reg = mmio_data_read(&mmio, ~0);

	ret = 0;
out_vgic_unlock:
	spin_unlock(&vgic->lock);
out:
	mutex_unlock(&dev->kvm->lock);
	return ret;
}

static int vgic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
	int r;

	switch (attr->group) {
	case KVM_DEV_ARM_VGIC_GRP_ADDR: {
		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
		u64 addr;
		unsigned long type = (unsigned long)attr->attr;

		if (copy_from_user(&addr, uaddr, sizeof(addr)))
			return -EFAULT;

		r = kvm_vgic_addr(dev->kvm, type, &addr, true);
		return (r == -ENODEV) ? -ENXIO : r;
	}

	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS: {
		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
		u32 reg;

		if (get_user(reg, uaddr))
			return -EFAULT;

		return vgic_attr_regs_access(dev, attr, &reg, true);
	}
	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS: {
		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
		u32 val;
		int ret = 0;

		if (get_user(val, uaddr))
			return -EFAULT;

		/*
		 * We require:
		 * - at least 32 SPIs on top of the 16 SGIs and 16 PPIs
		 * - at most 1024 interrupts
		 * - a multiple of 32 interrupts
		 */
		if (val < (VGIC_NR_PRIVATE_IRQS + 32) ||
		    val > VGIC_MAX_IRQS ||
		    (val & 31))
			return -EINVAL;

		mutex_lock(&dev->kvm->lock);

		if (vgic_initialized(dev->kvm) || dev->kvm->arch.vgic.nr_irqs)
			ret = -EBUSY;
		else
			dev->kvm->arch.vgic.nr_irqs = val;

		mutex_unlock(&dev->kvm->lock);

		return ret;
	}

	}

	return -ENXIO;
}

static int vgic_get_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
	int r = -ENXIO;

	switch (attr->group) {
	case KVM_DEV_ARM_VGIC_GRP_ADDR: {
		u64 __user *uaddr = (u64 __user *)(long)attr->addr;
		u64 addr;
		unsigned long type = (unsigned long)attr->attr;

		r = kvm_vgic_addr(dev->kvm, type, &addr, false);
		if (r)
			return (r == -ENODEV) ? -ENXIO : r;

		if (copy_to_user(uaddr, &addr, sizeof(addr)))
			return -EFAULT;
		break;
	}

	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS: {
		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
		u32 reg = 0;

		r = vgic_attr_regs_access(dev, attr, &reg, false);
		if (r)
			return r;
		r = put_user(reg, uaddr);
		break;
	}
	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS: {
		u32 __user *uaddr = (u32 __user *)(long)attr->addr;
		r = put_user(dev->kvm->arch.vgic.nr_irqs, uaddr);
		break;
	}

	}

	return r;
}

static int vgic_has_attr_regs(const struct mmio_range *ranges,
			      phys_addr_t offset)
{
	struct kvm_exit_mmio dev_attr_mmio;

	dev_attr_mmio.len = 4;
	if (find_matching_range(ranges, &dev_attr_mmio, offset))
		return 0;
	else
		return -ENXIO;
}

static int vgic_has_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
	phys_addr_t offset;

	switch (attr->group) {
	case KVM_DEV_ARM_VGIC_GRP_ADDR:
		switch (attr->attr) {
		case KVM_VGIC_V2_ADDR_TYPE_DIST:
		case KVM_VGIC_V2_ADDR_TYPE_CPU:
			return 0;
		}
		break;
	case KVM_DEV_ARM_VGIC_GRP_DIST_REGS:
		offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
		return vgic_has_attr_regs(vgic_dist_ranges, offset);
	case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
		offset = attr->attr & KVM_DEV_ARM_VGIC_OFFSET_MASK;
		return vgic_has_attr_regs(vgic_cpu_ranges, offset);
	case KVM_DEV_ARM_VGIC_GRP_NR_IRQS:
		return 0;
	}
	return -ENXIO;
}

static void vgic_destroy(struct kvm_device *dev)
{
	kfree(dev);
}

static int vgic_create(struct kvm_device *dev, u32 type)
{
	return kvm_vgic_create(dev->kvm);
}

static struct kvm_device_ops kvm_arm_vgic_v2_ops = {
	.name = "kvm-arm-vgic",
	.create = vgic_create,
	.destroy = vgic_destroy,
	.set_attr = vgic_set_attr,
	.get_attr = vgic_get_attr,
	.has_attr = vgic_has_attr,
};

static void vgic_init_maintenance_interrupt(void *info)
{
	enable_percpu_irq(vgic->maint_irq, 0);
}

static int vgic_cpu_notify(struct notifier_block *self,
			   unsigned long action, void *cpu)
{
	switch (action) {
	case CPU_STARTING:
	case CPU_STARTING_FROZEN:
		vgic_init_maintenance_interrupt(NULL);
		break;
	case CPU_DYING:
	case CPU_DYING_FROZEN:
		disable_percpu_irq(vgic->maint_irq);
		break;
	}

	return NOTIFY_OK;
}

static struct notifier_block vgic_cpu_nb = {
	.notifier_call = vgic_cpu_notify,
};

static const struct of_device_id vgic_ids[] = {
	{ .compatible = "arm,cortex-a15-gic", .data = vgic_v2_probe, },
	{ .compatible = "arm,gic-v3", .data = vgic_v3_probe, },
	{},
};

int kvm_vgic_hyp_init(void)
{
	const struct of_device_id *matched_id;
	const int (*vgic_probe)(struct device_node *,const struct vgic_ops **,
				const struct vgic_params **);
	struct device_node *vgic_node;
	int ret;

	vgic_node = of_find_matching_node_and_match(NULL,
						    vgic_ids, &matched_id);
	if (!vgic_node) {
		kvm_err("error: no compatible GIC node found\n");
		return -ENODEV;
	}

	vgic_probe = matched_id->data;
	ret = vgic_probe(vgic_node, &vgic_ops, &vgic);
	if (ret)
		return ret;

	ret = request_percpu_irq(vgic->maint_irq, vgic_maintenance_handler,
				 "vgic", kvm_get_running_vcpus());
	if (ret) {
		kvm_err("Cannot register interrupt %d\n", vgic->maint_irq);
		return ret;
	}

	ret = __register_cpu_notifier(&vgic_cpu_nb);
	if (ret) {
		kvm_err("Cannot register vgic CPU notifier\n");
		goto out_free_irq;
	}

	/* Callback into for arch code for setup */
	vgic_arch_setup(vgic);

	on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);

	return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
				       KVM_DEV_TYPE_ARM_VGIC_V2);

out_free_irq:
	free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
	return ret;
}