// SPDX-License-Identifier: GPL-2.0+
// Copyright 2017 IBM Corp.
#include <linux/sched/mm.h>
#include "trace.h"
#include "ocxl_internal.h"

int ocxl_context_alloc(struct ocxl_context **context, struct ocxl_afu *afu,
                struct address_space *mapping)
{
        int pasid;
        struct ocxl_context *ctx;

        ctx = kzalloc_obj(*ctx);
        if (!ctx)
                return -ENOMEM;

        ctx->afu = afu;
        mutex_lock(&afu->contexts_lock);
        pasid = idr_alloc(&afu->contexts_idr, ctx, afu->pasid_base,
                        afu->pasid_base + afu->pasid_max, GFP_KERNEL);
        if (pasid < 0) {
                mutex_unlock(&afu->contexts_lock);
                kfree(ctx);
                return pasid;
        }
        afu->pasid_count++;
        mutex_unlock(&afu->contexts_lock);

        ctx->pasid = pasid;
        ctx->status = OPENED;
        mutex_init(&ctx->status_mutex);
        ctx->mapping = mapping;
        mutex_init(&ctx->mapping_lock);
        init_waitqueue_head(&ctx->events_wq);
        mutex_init(&ctx->xsl_error_lock);
        mutex_init(&ctx->irq_lock);
        idr_init(&ctx->irq_idr);
        ctx->tidr = 0;

        /*
         * Keep a reference on the AFU to make sure it's valid for the
         * duration of the life of the context
         */
        ocxl_afu_get(afu);
        *context = ctx;
        return 0;
}
EXPORT_SYMBOL_GPL(ocxl_context_alloc);

/*
 * Callback for when a translation fault triggers an error
 * data:        a pointer to the context which triggered the fault
 * addr:        the address that triggered the error
 * dsisr:       the value of the PPC64 dsisr register
 */
static void xsl_fault_error(void *data, u64 addr, u64 dsisr)
{
        struct ocxl_context *ctx = data;

        mutex_lock(&ctx->xsl_error_lock);
        ctx->xsl_error.addr = addr;
        ctx->xsl_error.dsisr = dsisr;
        ctx->xsl_error.count++;
        mutex_unlock(&ctx->xsl_error_lock);

        wake_up_all(&ctx->events_wq);
}

int ocxl_context_attach(struct ocxl_context *ctx, u64 amr, struct mm_struct *mm)
{
        int rc;
        unsigned long pidr = 0;
        struct pci_dev *dev;

        // Locks both status & tidr
        mutex_lock(&ctx->status_mutex);
        if (ctx->status != OPENED) {
                rc = -EIO;
                goto out;
        }

        if (mm)
                pidr = mm->context.id;

        dev = to_pci_dev(ctx->afu->fn->dev.parent);
        rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid, pidr, ctx->tidr,
                              amr, pci_dev_id(dev), mm, xsl_fault_error, ctx);
        if (rc)
                goto out;

        ctx->status = ATTACHED;
out:
        mutex_unlock(&ctx->status_mutex);
        return rc;
}
EXPORT_SYMBOL_GPL(ocxl_context_attach);

static vm_fault_t map_afu_irq(struct vm_area_struct *vma, unsigned long address,
                u64 offset, struct ocxl_context *ctx)
{
        u64 trigger_addr;
        int irq_id = ocxl_irq_offset_to_id(ctx, offset);

        trigger_addr = ocxl_afu_irq_get_addr(ctx, irq_id);
        if (!trigger_addr)
                return VM_FAULT_SIGBUS;

        return vmf_insert_pfn(vma, address, trigger_addr >> PAGE_SHIFT);
}

static vm_fault_t map_pp_mmio(struct vm_area_struct *vma, unsigned long address,
                u64 offset, struct ocxl_context *ctx)
{
        u64 pp_mmio_addr;
        int pasid_off;
        vm_fault_t ret;

        if (offset >= ctx->afu->config.pp_mmio_stride)
                return VM_FAULT_SIGBUS;

        mutex_lock(&ctx->status_mutex);
        if (ctx->status != ATTACHED) {
                mutex_unlock(&ctx->status_mutex);
                pr_debug("%s: Context not attached, failing mmio mmap\n",
                        __func__);
                return VM_FAULT_SIGBUS;
        }

        pasid_off = ctx->pasid - ctx->afu->pasid_base;
        pp_mmio_addr = ctx->afu->pp_mmio_start +
                pasid_off * ctx->afu->config.pp_mmio_stride +
                offset;

        ret = vmf_insert_pfn(vma, address, pp_mmio_addr >> PAGE_SHIFT);
        mutex_unlock(&ctx->status_mutex);
        return ret;
}

static vm_fault_t ocxl_mmap_fault(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        struct ocxl_context *ctx = vma->vm_file->private_data;
        u64 offset;
        vm_fault_t ret;

        offset = vmf->pgoff << PAGE_SHIFT;
        pr_debug("%s: pasid %d address 0x%lx offset 0x%llx\n", __func__,
                ctx->pasid, vmf->address, offset);

        if (offset < ctx->afu->irq_base_offset)
                ret = map_pp_mmio(vma, vmf->address, offset, ctx);
        else
                ret = map_afu_irq(vma, vmf->address, offset, ctx);
        return ret;
}

static const struct vm_operations_struct ocxl_vmops = {
        .fault = ocxl_mmap_fault,
};

static int check_mmap_afu_irq(struct ocxl_context *ctx,
                        struct vm_area_struct *vma)
{
        int irq_id = ocxl_irq_offset_to_id(ctx, vma->vm_pgoff << PAGE_SHIFT);

        /* only one page */
        if (vma_pages(vma) != 1)
                return -EINVAL;

        /* check offset validty */
        if (!ocxl_afu_irq_get_addr(ctx, irq_id))
                return -EINVAL;

        /*
         * trigger page should only be accessible in write mode.
         *
         * It's a bit theoretical, as a page mmaped with only
         * PROT_WRITE is currently readable, but it doesn't hurt.
         */
        if ((vma->vm_flags & VM_READ) || (vma->vm_flags & VM_EXEC) ||
                !(vma->vm_flags & VM_WRITE))
                return -EINVAL;
        vm_flags_clear(vma, VM_MAYREAD | VM_MAYEXEC);
        return 0;
}

static int check_mmap_mmio(struct ocxl_context *ctx,
                        struct vm_area_struct *vma)
{
        if ((vma_pages(vma) + vma->vm_pgoff) >
                (ctx->afu->config.pp_mmio_stride >> PAGE_SHIFT))
                return -EINVAL;
        return 0;
}

int ocxl_context_mmap(struct ocxl_context *ctx, struct vm_area_struct *vma)
{
        int rc;

        if ((vma->vm_pgoff << PAGE_SHIFT) < ctx->afu->irq_base_offset)
                rc = check_mmap_mmio(ctx, vma);
        else
                rc = check_mmap_afu_irq(ctx, vma);
        if (rc)
                return rc;

        vm_flags_set(vma, VM_IO | VM_PFNMAP);
        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
        vma->vm_ops = &ocxl_vmops;
        return 0;
}

int ocxl_context_detach(struct ocxl_context *ctx)
{
        struct pci_dev *dev;
        int afu_control_pos;
        enum ocxl_context_status status;
        int rc;

        mutex_lock(&ctx->status_mutex);
        status = ctx->status;
        ctx->status = CLOSED;
        mutex_unlock(&ctx->status_mutex);
        if (status != ATTACHED)
                return 0;

        dev = to_pci_dev(ctx->afu->fn->dev.parent);
        afu_control_pos = ctx->afu->config.dvsec_afu_control_pos;

        mutex_lock(&ctx->afu->afu_control_lock);
        rc = ocxl_config_terminate_pasid(dev, afu_control_pos, ctx->pasid);
        mutex_unlock(&ctx->afu->afu_control_lock);
        trace_ocxl_terminate_pasid(ctx->pasid, rc);
        if (rc) {
                /*
                 * If we timeout waiting for the AFU to terminate the
                 * pasid, then it's dangerous to clean up the Process
                 * Element entry in the SPA, as it may be referenced
                 * in the future by the AFU. In which case, we would
                 * checkstop because of an invalid PE access (FIR
                 * register 2, bit 42). So leave the PE
                 * defined. Caller shouldn't free the context so that
                 * PASID remains allocated.
                 *
                 * A link reset will be required to cleanup the AFU
                 * and the SPA.
                 */
                if (rc == -EBUSY)
                        return rc;
        }
        rc = ocxl_link_remove_pe(ctx->afu->fn->link, ctx->pasid);
        if (rc) {
                dev_warn(&dev->dev,
                        "Couldn't remove PE entry cleanly: %d\n", rc);
        }
        return 0;
}
EXPORT_SYMBOL_GPL(ocxl_context_detach);

void ocxl_context_detach_all(struct ocxl_afu *afu)
{
        struct ocxl_context *ctx;
        int tmp;

        mutex_lock(&afu->contexts_lock);
        idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
                ocxl_context_detach(ctx);
                /*
                 * We are force detaching - remove any active mmio
                 * mappings so userspace cannot interfere with the
                 * card if it comes back.  Easiest way to exercise
                 * this is to unbind and rebind the driver via sysfs
                 * while it is in use.
                 */
                mutex_lock(&ctx->mapping_lock);
                if (ctx->mapping)
                        unmap_mapping_range(ctx->mapping, 0, 0, 1);
                mutex_unlock(&ctx->mapping_lock);
        }
        mutex_unlock(&afu->contexts_lock);
}

void ocxl_context_free(struct ocxl_context *ctx)
{
        mutex_lock(&ctx->afu->contexts_lock);
        ctx->afu->pasid_count--;
        idr_remove(&ctx->afu->contexts_idr, ctx->pasid);
        mutex_unlock(&ctx->afu->contexts_lock);

        ocxl_afu_irq_free_all(ctx);
        idr_destroy(&ctx->irq_idr);
        /* reference to the AFU taken in ocxl_context_alloc() */
        ocxl_afu_put(ctx->afu);
        kfree(ctx);
}
EXPORT_SYMBOL_GPL(ocxl_context_free);