/*
 * 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"

/*
 * Call this function to convert a u64 value to an unsigned long * bitmask
 * in a way that works on both 32-bit and 64-bit LE and BE platforms.
 *
 * Warning: Calling this function may modify *val.
 */
static unsigned long *u64_to_bitmask(u64 *val)
{
#if defined(CONFIG_CPU_BIG_ENDIAN) && BITS_PER_LONG == 32
        *val = (*val >> 32) | (*val << 32);
#endif
        return (unsigned long *)val;
}

void vgic_v2_process_maintenance(struct kvm_vcpu *vcpu)
{
        struct vgic_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;

        if (cpuif->vgic_misr & GICH_MISR_EOI) {
                u64 eisr = cpuif->vgic_eisr;
                unsigned long *eisr_bmap = u64_to_bitmask(&eisr);
                int lr;

                for_each_set_bit(lr, eisr_bmap, kvm_vgic_global_state.nr_lr) {
                        u32 intid = cpuif->vgic_lr[lr] & GICH_LR_VIRTUALID;

                        WARN_ON(cpuif->vgic_lr[lr] & GICH_LR_STATE);

                        /* Only SPIs require notification */
                        if (vgic_valid_spi(vcpu->kvm, intid))
                                kvm_notify_acked_irq(vcpu->kvm, 0,
                                                     intid - VGIC_NR_PRIVATE_IRQS);
                }
        }

        /* check and disable underflow maintenance IRQ */
        cpuif->vgic_hcr &= ~GICH_HCR_UIE;

        /*
         * In the next iterations of the vcpu loop, if we sync the
         * vgic state after flushing it, but before entering the guest
         * (this happens for pending signals and vmid rollovers), then
         * make sure we don't pick up any old maintenance interrupts
         * here.
         */
        cpuif->vgic_eisr = 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;
}

/*
 * 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_v2_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v2;
        int lr;

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

                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);

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

                        if (vgic_irq_is_sgi(intid)) {
                                u32 cpuid = val & GICH_LR_PHYSID_CPUID;

                                cpuid >>= GICH_LR_PHYSID_CPUID_SHIFT;
                                irq->source |= (1 << cpuid);
                        }
                }

                /*
                 * Clear soft pending state when level irqs have been acked.
                 * Always regenerate the pending state.
                 */
                if (irq->config == VGIC_CONFIG_LEVEL) {
                        if (!(val & GICH_LR_PENDING_BIT))
                                irq->soft_pending = false;

                        irq->pending = irq->line_level || irq->soft_pending;
                }

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

/*
 * 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;

        if (irq->pending) {
                val |= GICH_LR_PENDING_BIT;

                if (irq->config == VGIC_CONFIG_EDGE)
                        irq->pending = 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 = true;
                }
        }

        if (irq->active)
                val |= GICH_LR_ACTIVE_BIT;

        if (irq->hw) {
                val |= GICH_LR_HW;
                val |= irq->hwintid << GICH_LR_PHYSID_CPUID_SHIFT;
        } else {
                if (irq->config == VGIC_CONFIG_LEVEL)
                        val |= GICH_LR_EOI;
        }

        /* 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)
{
        u32 vmcr;

        vmcr  = (vmcrp->ctlr << GICH_VMCR_CTRL_SHIFT) & GICH_VMCR_CTRL_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 << GICH_VMCR_PRIMASK_SHIFT) &
                GICH_VMCR_PRIMASK_MASK;

        vcpu->arch.vgic_cpu.vgic_v2.vgic_vmcr = vmcr;
}

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

        vmcrp->ctlr = (vmcr & GICH_VMCR_CTRL_MASK) >>
                        GICH_VMCR_CTRL_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;
}

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;
        vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr = ~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:
        if (ret)
                kvm_vgic_destroy(kvm);
        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");
                kvm_vgic_global_state.vcpu_base_va = ioremap(info->vcpu.start,
                                                             resource_size(&info->vcpu));
                if (!kvm_vgic_global_state.vcpu_base_va) {
                        kvm_err("Cannot ioremap GICV\n");
                        return -ENOMEM;
                }

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

                static_branch_enable(&vgic_v2_cpuif_trap);
        }

        kvm_vgic_global_state.vctrl_base = ioremap(info->vctrl.start,
                                                   resource_size(&info->vctrl));
        if (!kvm_vgic_global_state.vctrl_base) {
                kvm_err("Cannot ioremap GICH\n");
                ret = -ENOMEM;
                goto out;
        }

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

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

        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_info("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;
}