/*
 * Copyright (C) 2015, 2016 ARM Ltd.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/irqchip/arm-gic.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <kvm/arm_vgic.h>
#include <asm/kvm_mmu.h>

#include "vgic.h"

static inline void vgic_v2_write_lr(int lr, u32 val)
{
	void __iomem *base = kvm_vgic_global_state.vctrl_base;

	writel_relaxed(val, base + GICH_LR0 + (lr * 4));
}

void vgic_v2_init_lrs(void)
{
	int i;

	for (i = 0; i < kvm_vgic_global_state.nr_lr; i++)
		vgic_v2_write_lr(i, 0);
}

void vgic_v2_set_underflow(struct kvm_vcpu *vcpu)
{
	struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;

	cpuif->vgic_hcr |= GICH_HCR_UIE;
}

static bool lr_signals_eoi_mi(u32 lr_val)
{
	return !(lr_val & GICH_LR_STATE) && (lr_val & GICH_LR_EOI) &&
	       !(lr_val & GICH_LR_HW);
}

/*
 * transfer the content of the LRs back into the corresponding ap_list:
 * - active bit is transferred as is
 * - pending bit is
 *   - transferred as is in case of edge sensitive IRQs
 *   - set to the line-level (resample time) for level sensitive IRQs
 */
void vgic_v2_fold_lr_state(struct kvm_vcpu *vcpu)
{
	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
	struct vgic_v2_cpu_if *cpuif = &vgic_cpu->vgic_v2;
	int lr;

	DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());

	cpuif->vgic_hcr &= ~GICH_HCR_UIE;

	for (lr = 0; lr < vgic_cpu->used_lrs; lr++) {
		u32 val = cpuif->vgic_lr[lr];
		u32 cpuid, intid = val & GICH_LR_VIRTUALID;
		struct vgic_irq *irq;

		/* Extract the source vCPU id from the LR */
		cpuid = val & GICH_LR_PHYSID_CPUID;
		cpuid >>= GICH_LR_PHYSID_CPUID_SHIFT;
		cpuid &= 7;

		/* Notify fds when the guest EOI'ed a level-triggered SPI */
		if (lr_signals_eoi_mi(val) && vgic_valid_spi(vcpu->kvm, intid))
			kvm_notify_acked_irq(vcpu->kvm, 0,
					     intid - VGIC_NR_PRIVATE_IRQS);

		irq = vgic_get_irq(vcpu->kvm, vcpu, intid);

		spin_lock(&irq->irq_lock);

		/* Always preserve the active bit */
		irq->active = !!(val & GICH_LR_ACTIVE_BIT);

		if (irq->active && vgic_irq_is_sgi(intid))
			irq->active_source = cpuid;

		/* Edge is the only case where we preserve the pending bit */
		if (irq->config == VGIC_CONFIG_EDGE &&
		    (val & GICH_LR_PENDING_BIT)) {
			irq->pending_latch = true;

			if (vgic_irq_is_sgi(intid))
				irq->source |= (1 << cpuid);
		}

		/*
		 * Clear soft pending state when level irqs have been acked.
		 */
		if (irq->config == VGIC_CONFIG_LEVEL && !(val & GICH_LR_STATE))
			irq->pending_latch = false;

		/*
		 * Level-triggered mapped IRQs are special because we only
		 * observe rising edges as input to the VGIC.
		 *
		 * If the guest never acked the interrupt we have to sample
		 * the physical line and set the line level, because the
		 * device state could have changed or we simply need to
		 * process the still pending interrupt later.
		 *
		 * If this causes us to lower the level, we have to also clear
		 * the physical active state, since we will otherwise never be
		 * told when the interrupt becomes asserted again.
		 */
		if (vgic_irq_is_mapped_level(irq) && (val & GICH_LR_PENDING_BIT)) {
			irq->line_level = vgic_get_phys_line_level(irq);

			if (!irq->line_level)
				vgic_irq_set_phys_active(irq, false);
		}

		spin_unlock(&irq->irq_lock);
		vgic_put_irq(vcpu->kvm, irq);
	}

	vgic_cpu->used_lrs = 0;
}

/*
 * Populates the particular LR with the state of a given IRQ:
 * - for an edge sensitive IRQ the pending state is cleared in struct vgic_irq
 * - for a level sensitive IRQ the pending state value is unchanged;
 *   it is dictated directly by the input level
 *
 * If @irq describes an SGI with multiple sources, we choose the
 * lowest-numbered source VCPU and clear that bit in the source bitmap.
 *
 * The irq_lock must be held by the caller.
 */
void vgic_v2_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
{
	u32 val = irq->intid;
	bool allow_pending = true;

	if (irq->active) {
		val |= GICH_LR_ACTIVE_BIT;
		if (vgic_irq_is_sgi(irq->intid))
			val |= irq->active_source << GICH_LR_PHYSID_CPUID_SHIFT;
		if (vgic_irq_is_multi_sgi(irq)) {
			allow_pending = false;
			val |= GICH_LR_EOI;
		}
	}

	if (irq->group)
		val |= GICH_LR_GROUP1;

	if (irq->hw) {
		val |= GICH_LR_HW;
		val |= irq->hwintid << GICH_LR_PHYSID_CPUID_SHIFT;
		/*
		 * Never set pending+active on a HW interrupt, as the
		 * pending state is kept at the physical distributor
		 * level.
		 */
		if (irq->active)
			allow_pending = false;
	} else {
		if (irq->config == VGIC_CONFIG_LEVEL) {
			val |= GICH_LR_EOI;

			/*
			 * Software resampling doesn't work very well
			 * if we allow P+A, so let's not do that.
			 */
			if (irq->active)
				allow_pending = false;
		}
	}

	if (allow_pending && irq_is_pending(irq)) {
		val |= GICH_LR_PENDING_BIT;

		if (irq->config == VGIC_CONFIG_EDGE)
			irq->pending_latch = false;

		if (vgic_irq_is_sgi(irq->intid)) {
			u32 src = ffs(irq->source);

			BUG_ON(!src);
			val |= (src - 1) << GICH_LR_PHYSID_CPUID_SHIFT;
			irq->source &= ~(1 << (src - 1));
			if (irq->source) {
				irq->pending_latch = true;
				val |= GICH_LR_EOI;
			}
		}
	}

	/*
	 * Level-triggered mapped IRQs are special because we only observe
	 * rising edges as input to the VGIC.  We therefore lower the line
	 * level here, so that we can take new virtual IRQs.  See
	 * vgic_v2_fold_lr_state for more info.
	 */
	if (vgic_irq_is_mapped_level(irq) && (val & GICH_LR_PENDING_BIT))
		irq->line_level = false;

	/* The GICv2 LR only holds five bits of priority. */
	val |= (irq->priority >> 3) << GICH_LR_PRIORITY_SHIFT;

	vcpu->arch.vgic_cpu.vgic_v2.vgic_lr[lr] = val;
}

void vgic_v2_clear_lr(struct kvm_vcpu *vcpu, int lr)
{
	vcpu->arch.vgic_cpu.vgic_v2.vgic_lr[lr] = 0;
}

void vgic_v2_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
{
	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
	u32 vmcr;

	vmcr = (vmcrp->grpen0 << GICH_VMCR_ENABLE_GRP0_SHIFT) &
		GICH_VMCR_ENABLE_GRP0_MASK;
	vmcr |= (vmcrp->grpen1 << GICH_VMCR_ENABLE_GRP1_SHIFT) &
		GICH_VMCR_ENABLE_GRP1_MASK;
	vmcr |= (vmcrp->ackctl << GICH_VMCR_ACK_CTL_SHIFT) &
		GICH_VMCR_ACK_CTL_MASK;
	vmcr |= (vmcrp->fiqen << GICH_VMCR_FIQ_EN_SHIFT) &
		GICH_VMCR_FIQ_EN_MASK;
	vmcr |= (vmcrp->cbpr << GICH_VMCR_CBPR_SHIFT) &
		GICH_VMCR_CBPR_MASK;
	vmcr |= (vmcrp->eoim << GICH_VMCR_EOI_MODE_SHIFT) &
		GICH_VMCR_EOI_MODE_MASK;
	vmcr |= (vmcrp->abpr << GICH_VMCR_ALIAS_BINPOINT_SHIFT) &
		GICH_VMCR_ALIAS_BINPOINT_MASK;
	vmcr |= (vmcrp->bpr << GICH_VMCR_BINPOINT_SHIFT) &
		GICH_VMCR_BINPOINT_MASK;
	vmcr |= ((vmcrp->pmr >> GICV_PMR_PRIORITY_SHIFT) <<
		 GICH_VMCR_PRIMASK_SHIFT) & GICH_VMCR_PRIMASK_MASK;

	cpu_if->vgic_vmcr = vmcr;
}

void vgic_v2_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
{
	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
	u32 vmcr;

	vmcr = cpu_if->vgic_vmcr;

	vmcrp->grpen0 = (vmcr & GICH_VMCR_ENABLE_GRP0_MASK) >>
		GICH_VMCR_ENABLE_GRP0_SHIFT;
	vmcrp->grpen1 = (vmcr & GICH_VMCR_ENABLE_GRP1_MASK) >>
		GICH_VMCR_ENABLE_GRP1_SHIFT;
	vmcrp->ackctl = (vmcr & GICH_VMCR_ACK_CTL_MASK) >>
		GICH_VMCR_ACK_CTL_SHIFT;
	vmcrp->fiqen = (vmcr & GICH_VMCR_FIQ_EN_MASK) >>
		GICH_VMCR_FIQ_EN_SHIFT;
	vmcrp->cbpr = (vmcr & GICH_VMCR_CBPR_MASK) >>
		GICH_VMCR_CBPR_SHIFT;
	vmcrp->eoim = (vmcr & GICH_VMCR_EOI_MODE_MASK) >>
		GICH_VMCR_EOI_MODE_SHIFT;

	vmcrp->abpr = (vmcr & GICH_VMCR_ALIAS_BINPOINT_MASK) >>
			GICH_VMCR_ALIAS_BINPOINT_SHIFT;
	vmcrp->bpr  = (vmcr & GICH_VMCR_BINPOINT_MASK) >>
			GICH_VMCR_BINPOINT_SHIFT;
	vmcrp->pmr  = ((vmcr & GICH_VMCR_PRIMASK_MASK) >>
			GICH_VMCR_PRIMASK_SHIFT) << GICV_PMR_PRIORITY_SHIFT;
}

void vgic_v2_enable(struct kvm_vcpu *vcpu)
{
	/*
	 * By forcing VMCR to zero, the GIC will restore the binary
	 * points to their reset values. Anything else resets to zero
	 * anyway.
	 */
	vcpu->arch.vgic_cpu.vgic_v2.vgic_vmcr = 0;

	/* Get the show on the road... */
	vcpu->arch.vgic_cpu.vgic_v2.vgic_hcr = GICH_HCR_EN;
}

/* check for overlapping regions and for regions crossing the end of memory */
static bool vgic_v2_check_base(gpa_t dist_base, gpa_t cpu_base)
{
	if (dist_base + KVM_VGIC_V2_DIST_SIZE < dist_base)
		return false;
	if (cpu_base + KVM_VGIC_V2_CPU_SIZE < cpu_base)
		return false;

	if (dist_base + KVM_VGIC_V2_DIST_SIZE <= cpu_base)
		return true;
	if (cpu_base + KVM_VGIC_V2_CPU_SIZE <= dist_base)
		return true;

	return false;
}

int vgic_v2_map_resources(struct kvm *kvm)
{
	struct vgic_dist *dist = &kvm->arch.vgic;
	int ret = 0;

	if (vgic_ready(kvm))
		goto out;

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

	if (!vgic_v2_check_base(dist->vgic_dist_base, dist->vgic_cpu_base)) {
		kvm_err("VGIC CPU and dist frames overlap\n");
		ret = -EINVAL;
		goto out;
	}

	/*
	 * Initialize the vgic if this hasn't already been done on demand by
	 * accessing the vgic state from userspace.
	 */
	ret = vgic_init(kvm);
	if (ret) {
		kvm_err("Unable to initialize VGIC dynamic data structures\n");
		goto out;
	}

	ret = vgic_register_dist_iodev(kvm, dist->vgic_dist_base, VGIC_V2);
	if (ret) {
		kvm_err("Unable to register VGIC MMIO regions\n");
		goto out;
	}

	if (!static_branch_unlikely(&vgic_v2_cpuif_trap)) {
		ret = kvm_phys_addr_ioremap(kvm, dist->vgic_cpu_base,
					    kvm_vgic_global_state.vcpu_base,
					    KVM_VGIC_V2_CPU_SIZE, true);
		if (ret) {
			kvm_err("Unable to remap VGIC CPU to VCPU\n");
			goto out;
		}
	}

	dist->ready = true;

out:
	return ret;
}

DEFINE_STATIC_KEY_FALSE(vgic_v2_cpuif_trap);

/**
 * vgic_v2_probe - probe for a GICv2 compatible interrupt controller in DT
 * @node:	pointer to the DT node
 *
 * Returns 0 if a GICv2 has been found, returns an error code otherwise
 */
int vgic_v2_probe(const struct gic_kvm_info *info)
{
	int ret;
	u32 vtr;

	if (!info->vctrl.start) {
		kvm_err("GICH not present in the firmware table\n");
		return -ENXIO;
	}

	if (!PAGE_ALIGNED(info->vcpu.start) ||
	    !PAGE_ALIGNED(resource_size(&info->vcpu))) {
		kvm_info("GICV region size/alignment is unsafe, using trapping (reduced performance)\n");

		ret = create_hyp_io_mappings(info->vcpu.start,
					     resource_size(&info->vcpu),
					     &kvm_vgic_global_state.vcpu_base_va,
					     &kvm_vgic_global_state.vcpu_hyp_va);
		if (ret) {
			kvm_err("Cannot map GICV into hyp\n");
			goto out;
		}

		static_branch_enable(&vgic_v2_cpuif_trap);
	}

	ret = create_hyp_io_mappings(info->vctrl.start,
				     resource_size(&info->vctrl),
				     &kvm_vgic_global_state.vctrl_base,
				     &kvm_vgic_global_state.vctrl_hyp);
	if (ret) {
		kvm_err("Cannot map VCTRL into hyp\n");
		goto out;
	}

	vtr = readl_relaxed(kvm_vgic_global_state.vctrl_base + GICH_VTR);
	kvm_vgic_global_state.nr_lr = (vtr & 0x3f) + 1;

	ret = kvm_register_vgic_device(KVM_DEV_TYPE_ARM_VGIC_V2);
	if (ret) {
		kvm_err("Cannot register GICv2 KVM device\n");
		goto out;
	}

	kvm_vgic_global_state.can_emulate_gicv2 = true;
	kvm_vgic_global_state.vcpu_base = info->vcpu.start;
	kvm_vgic_global_state.type = VGIC_V2;
	kvm_vgic_global_state.max_gic_vcpus = VGIC_V2_MAX_CPUS;

	kvm_debug("vgic-v2@%llx\n", info->vctrl.start);

	return 0;
out:
	if (kvm_vgic_global_state.vctrl_base)
		iounmap(kvm_vgic_global_state.vctrl_base);
	if (kvm_vgic_global_state.vcpu_base_va)
		iounmap(kvm_vgic_global_state.vcpu_base_va);

	return ret;
}

static void save_lrs(struct kvm_vcpu *vcpu, void __iomem *base)
{
	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
	u64 elrsr;
	int i;

	elrsr = readl_relaxed(base + GICH_ELRSR0);
	if (unlikely(used_lrs > 32))
		elrsr |= ((u64)readl_relaxed(base + GICH_ELRSR1)) << 32;

	for (i = 0; i < used_lrs; i++) {
		if (elrsr & (1UL << i))
			cpu_if->vgic_lr[i] &= ~GICH_LR_STATE;
		else
			cpu_if->vgic_lr[i] = readl_relaxed(base + GICH_LR0 + (i * 4));

		writel_relaxed(0, base + GICH_LR0 + (i * 4));
	}
}

void vgic_v2_save_state(struct kvm_vcpu *vcpu)
{
	void __iomem *base = kvm_vgic_global_state.vctrl_base;
	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;

	if (!base)
		return;

	if (used_lrs) {
		save_lrs(vcpu, base);
		writel_relaxed(0, base + GICH_HCR);
	}
}

void vgic_v2_restore_state(struct kvm_vcpu *vcpu)
{
	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
	void __iomem *base = kvm_vgic_global_state.vctrl_base;
	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
	int i;

	if (!base)
		return;

	if (used_lrs) {
		writel_relaxed(cpu_if->vgic_hcr, base + GICH_HCR);
		for (i = 0; i < used_lrs; i++) {
			writel_relaxed(cpu_if->vgic_lr[i],
				       base + GICH_LR0 + (i * 4));
		}
	}
}

void vgic_v2_load(struct kvm_vcpu *vcpu)
{
	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;

	writel_relaxed(cpu_if->vgic_vmcr,
		       kvm_vgic_global_state.vctrl_base + GICH_VMCR);
	writel_relaxed(cpu_if->vgic_apr,
		       kvm_vgic_global_state.vctrl_base + GICH_APR);
}

void vgic_v2_put(struct kvm_vcpu *vcpu)
{
	struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;

	cpu_if->vgic_vmcr = readl_relaxed(kvm_vgic_global_state.vctrl_base + GICH_VMCR);
	cpu_if->vgic_apr = readl_relaxed(kvm_vgic_global_state.vctrl_base + GICH_APR);
}