Merge tag 'trace-v5.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[linux-2.6-block.git] / drivers / gpu / drm / i915 / gt / uc / intel_guc_submission.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2014 Intel Corporation
 */

#include <linux/circ_buf.h>

#include "gem/i915_gem_context.h"

#include "gt/intel_context.h"
#include "gt/intel_engine_pm.h"
#include "gt/intel_gt.h"
#include "gt/intel_gt_pm.h"
#include "gt/intel_lrc_reg.h"
#include "intel_guc_submission.h"

#include "i915_drv.h"
#include "i915_trace.h"

enum {
        GUC_PREEMPT_NONE = 0,
        GUC_PREEMPT_INPROGRESS,
        GUC_PREEMPT_FINISHED,
};
#define GUC_PREEMPT_BREADCRUMB_DWORDS   0x8
#define GUC_PREEMPT_BREADCRUMB_BYTES    \
        (sizeof(u32) * GUC_PREEMPT_BREADCRUMB_DWORDS)

/**
 * DOC: GuC-based command submission
 *
 * GuC client:
 * A intel_guc_client refers to a submission path through GuC. Currently, there
 * is only one client, which is charged with all submissions to the GuC. This
 * struct is the owner of a doorbell, a process descriptor and a workqueue (all
 * of them inside a single gem object that contains all required pages for these
 * elements).
 *
 * GuC stage descriptor:
 * During initialization, the driver allocates a static pool of 1024 such
 * descriptors, and shares them with the GuC.
 * Currently, there exists a 1:1 mapping between a intel_guc_client and a
 * guc_stage_desc (via the client's stage_id), so effectively only one
 * gets used. This stage descriptor lets the GuC know about the doorbell,
 * workqueue and process descriptor. Theoretically, it also lets the GuC
 * know about our HW contexts (context ID, etc...), but we actually
 * employ a kind of submission where the GuC uses the LRCA sent via the work
 * item instead (the single guc_stage_desc associated to execbuf client
 * contains information about the default kernel context only, but this is
 * essentially unused). This is called a "proxy" submission.
 *
 * The Scratch registers:
 * There are 16 MMIO-based registers start from 0xC180. The kernel driver writes
 * a value to the action register (SOFT_SCRATCH_0) along with any data. It then
 * triggers an interrupt on the GuC via another register write (0xC4C8).
 * Firmware writes a success/fail code back to the action register after
 * processes the request. The kernel driver polls waiting for this update and
 * then proceeds.
 * See intel_guc_send()
 *
 * Doorbells:
 * Doorbells are interrupts to uKernel. A doorbell is a single cache line (QW)
 * mapped into process space.
 *
 * Work Items:
 * There are several types of work items that the host may place into a
 * workqueue, each with its own requirements and limitations. Currently only
 * WQ_TYPE_INORDER is needed to support legacy submission via GuC, which
 * represents in-order queue. The kernel driver packs ring tail pointer and an
 * ELSP context descriptor dword into Work Item.
 * See guc_add_request()
 *
 */

static inline struct i915_priolist *to_priolist(struct rb_node *rb)
{
        return rb_entry(rb, struct i915_priolist, node);
}

static inline bool is_high_priority(struct intel_guc_client *client)
{
        return (client->priority == GUC_CLIENT_PRIORITY_KMD_HIGH ||
                client->priority == GUC_CLIENT_PRIORITY_HIGH);
}

static int reserve_doorbell(struct intel_guc_client *client)
{
        unsigned long offset;
        unsigned long end;
        u16 id;

        GEM_BUG_ON(client->doorbell_id != GUC_DOORBELL_INVALID);

        /*
         * The bitmap tracks which doorbell registers are currently in use.
         * It is split into two halves; the first half is used for normal
         * priority contexts, the second half for high-priority ones.
         */
        offset = 0;
        end = GUC_NUM_DOORBELLS / 2;
        if (is_high_priority(client)) {
                offset = end;
                end += offset;
        }

        id = find_next_zero_bit(client->guc->doorbell_bitmap, end, offset);
        if (id == end)
                return -ENOSPC;

        __set_bit(id, client->guc->doorbell_bitmap);
        client->doorbell_id = id;
        DRM_DEBUG_DRIVER("client %u (high prio=%s) reserved doorbell: %d\n",
                         client->stage_id, yesno(is_high_priority(client)),
                         id);
        return 0;
}

static bool has_doorbell(struct intel_guc_client *client)
{
        if (client->doorbell_id == GUC_DOORBELL_INVALID)
                return false;

        return test_bit(client->doorbell_id, client->guc->doorbell_bitmap);
}

static void unreserve_doorbell(struct intel_guc_client *client)
{
        GEM_BUG_ON(!has_doorbell(client));

        __clear_bit(client->doorbell_id, client->guc->doorbell_bitmap);
        client->doorbell_id = GUC_DOORBELL_INVALID;
}

/*
 * Tell the GuC to allocate or deallocate a specific doorbell
 */

static int __guc_allocate_doorbell(struct intel_guc *guc, u32 stage_id)
{
        u32 action[] = {
                INTEL_GUC_ACTION_ALLOCATE_DOORBELL,
                stage_id
        };

        return intel_guc_send(guc, action, ARRAY_SIZE(action));
}

static int __guc_deallocate_doorbell(struct intel_guc *guc, u32 stage_id)
{
        u32 action[] = {
                INTEL_GUC_ACTION_DEALLOCATE_DOORBELL,
                stage_id
        };

        return intel_guc_send(guc, action, ARRAY_SIZE(action));
}

static struct guc_stage_desc *__get_stage_desc(struct intel_guc_client *client)
{
        struct guc_stage_desc *base = client->guc->stage_desc_pool_vaddr;

        return &base[client->stage_id];
}

/*
 * Initialise, update, or clear doorbell data shared with the GuC
 *
 * These functions modify shared data and so need access to the mapped
 * client object which contains the page being used for the doorbell
 */

static void __update_doorbell_desc(struct intel_guc_client *client, u16 new_id)
{
        struct guc_stage_desc *desc;

        /* Update the GuC's idea of the doorbell ID */
        desc = __get_stage_desc(client);
        desc->db_id = new_id;
}

static struct guc_doorbell_info *__get_doorbell(struct intel_guc_client *client)
{
        return client->vaddr + client->doorbell_offset;
}

static bool __doorbell_valid(struct intel_guc *guc, u16 db_id)
{
        struct intel_uncore *uncore = guc_to_gt(guc)->uncore;

        GEM_BUG_ON(db_id >= GUC_NUM_DOORBELLS);
        return intel_uncore_read(uncore, GEN8_DRBREGL(db_id)) & GEN8_DRB_VALID;
}

static void __init_doorbell(struct intel_guc_client *client)
{
        struct guc_doorbell_info *doorbell;

        doorbell = __get_doorbell(client);
        doorbell->db_status = GUC_DOORBELL_ENABLED;
        doorbell->cookie = 0;
}

static void __fini_doorbell(struct intel_guc_client *client)
{
        struct guc_doorbell_info *doorbell;
        u16 db_id = client->doorbell_id;

        doorbell = __get_doorbell(client);
        doorbell->db_status = GUC_DOORBELL_DISABLED;

        /* Doorbell release flow requires that we wait for GEN8_DRB_VALID bit
         * to go to zero after updating db_status before we call the GuC to
         * release the doorbell
         */
        if (wait_for_us(!__doorbell_valid(client->guc, db_id), 10))
                WARN_ONCE(true, "Doorbell never became invalid after disable\n");
}

static int create_doorbell(struct intel_guc_client *client)
{
        int ret;

        if (WARN_ON(!has_doorbell(client)))
                return -ENODEV; /* internal setup error, should never happen */

        __update_doorbell_desc(client, client->doorbell_id);
        __init_doorbell(client);

        ret = __guc_allocate_doorbell(client->guc, client->stage_id);
        if (ret) {
                __fini_doorbell(client);
                __update_doorbell_desc(client, GUC_DOORBELL_INVALID);
                DRM_DEBUG_DRIVER("Couldn't create client %u doorbell: %d\n",
                                 client->stage_id, ret);
                return ret;
        }

        return 0;
}

static int destroy_doorbell(struct intel_guc_client *client)
{
        int ret;

        GEM_BUG_ON(!has_doorbell(client));

        __fini_doorbell(client);
        ret = __guc_deallocate_doorbell(client->guc, client->stage_id);
        if (ret)
                DRM_ERROR("Couldn't destroy client %u doorbell: %d\n",
                          client->stage_id, ret);

        __update_doorbell_desc(client, GUC_DOORBELL_INVALID);

        return ret;
}

static unsigned long __select_cacheline(struct intel_guc *guc)
{
        unsigned long offset;

        /* Doorbell uses a single cache line within a page */
        offset = offset_in_page(guc->db_cacheline);

        /* Moving to next cache line to reduce contention */
        guc->db_cacheline += cache_line_size();

        DRM_DEBUG_DRIVER("reserved cacheline 0x%lx, next 0x%x, linesize %u\n",
                         offset, guc->db_cacheline, cache_line_size());
        return offset;
}

static inline struct guc_process_desc *
__get_process_desc(struct intel_guc_client *client)
{
        return client->vaddr + client->proc_desc_offset;
}

/*
 * Initialise the process descriptor shared with the GuC firmware.
 */
static void guc_proc_desc_init(struct intel_guc_client *client)
{
        struct guc_process_desc *desc;

        desc = memset(__get_process_desc(client), 0, sizeof(*desc));

        /*
         * XXX: pDoorbell and WQVBaseAddress are pointers in process address
         * space for ring3 clients (set them as in mmap_ioctl) or kernel
         * space for kernel clients (map on demand instead? May make debug
         * easier to have it mapped).
         */
        desc->wq_base_addr = 0;
        desc->db_base_addr = 0;

        desc->stage_id = client->stage_id;
        desc->wq_size_bytes = GUC_WQ_SIZE;
        desc->wq_status = WQ_STATUS_ACTIVE;
        desc->priority = client->priority;
}

static void guc_proc_desc_fini(struct intel_guc_client *client)
{
        struct guc_process_desc *desc;

        desc = __get_process_desc(client);
        memset(desc, 0, sizeof(*desc));
}

static int guc_stage_desc_pool_create(struct intel_guc *guc)
{
        struct i915_vma *vma;
        void *vaddr;

        vma = intel_guc_allocate_vma(guc,
                                     PAGE_ALIGN(sizeof(struct guc_stage_desc) *
                                     GUC_MAX_STAGE_DESCRIPTORS));
        if (IS_ERR(vma))
                return PTR_ERR(vma);

        vaddr = i915_gem_object_pin_map(vma->obj, I915_MAP_WB);
        if (IS_ERR(vaddr)) {
                i915_vma_unpin_and_release(&vma, 0);
                return PTR_ERR(vaddr);
        }

        guc->stage_desc_pool = vma;
        guc->stage_desc_pool_vaddr = vaddr;
        ida_init(&guc->stage_ids);

        return 0;
}

static void guc_stage_desc_pool_destroy(struct intel_guc *guc)
{
        ida_destroy(&guc->stage_ids);
        i915_vma_unpin_and_release(&guc->stage_desc_pool, I915_VMA_RELEASE_MAP);
}

/*
 * Initialise/clear the stage descriptor shared with the GuC firmware.
 *
 * This descriptor tells the GuC where (in GGTT space) to find the important
 * data structures relating to this client (doorbell, process descriptor,
 * write queue, etc).
 */
static void guc_stage_desc_init(struct intel_guc_client *client)
{
        struct intel_guc *guc = client->guc;
        struct guc_stage_desc *desc;
        u32 gfx_addr;

        desc = __get_stage_desc(client);
        memset(desc, 0, sizeof(*desc));

        desc->attribute = GUC_STAGE_DESC_ATTR_ACTIVE |
                          GUC_STAGE_DESC_ATTR_KERNEL;
        if (is_high_priority(client))
                desc->attribute |= GUC_STAGE_DESC_ATTR_PREEMPT;
        desc->stage_id = client->stage_id;
        desc->priority = client->priority;
        desc->db_id = client->doorbell_id;

        /*
         * The doorbell, process descriptor, and workqueue are all parts
         * of the client object, which the GuC will reference via the GGTT
         */
        gfx_addr = intel_guc_ggtt_offset(guc, client->vma);
        desc->db_trigger_phy = sg_dma_address(client->vma->pages->sgl) +
                                client->doorbell_offset;
        desc->db_trigger_cpu = ptr_to_u64(__get_doorbell(client));
        desc->db_trigger_uk = gfx_addr + client->doorbell_offset;
        desc->process_desc = gfx_addr + client->proc_desc_offset;
        desc->wq_addr = gfx_addr + GUC_DB_SIZE;
        desc->wq_size = GUC_WQ_SIZE;

        desc->desc_private = ptr_to_u64(client);
}

static void guc_stage_desc_fini(struct intel_guc_client *client)
{
        struct guc_stage_desc *desc;

        desc = __get_stage_desc(client);
        memset(desc, 0, sizeof(*desc));
}

/* Construct a Work Item and append it to the GuC's Work Queue */
static void guc_wq_item_append(struct intel_guc_client *client,
                               u32 target_engine, u32 context_desc,
                               u32 ring_tail, u32 fence_id)
{
        /* wqi_len is in DWords, and does not include the one-word header */
        const size_t wqi_size = sizeof(struct guc_wq_item);
        const u32 wqi_len = wqi_size / sizeof(u32) - 1;
        struct guc_process_desc *desc = __get_process_desc(client);
        struct guc_wq_item *wqi;
        u32 wq_off;

        lockdep_assert_held(&client->wq_lock);

        /* For now workqueue item is 4 DWs; workqueue buffer is 2 pages. So we
         * should not have the case where structure wqi is across page, neither
         * wrapped to the beginning. This simplifies the implementation below.
         *
         * XXX: if not the case, we need save data to a temp wqi and copy it to
         * workqueue buffer dw by dw.
         */
        BUILD_BUG_ON(wqi_size != 16);

        /* We expect the WQ to be active if we're appending items to it */
        GEM_BUG_ON(desc->wq_status != WQ_STATUS_ACTIVE);

        /* Free space is guaranteed. */
        wq_off = READ_ONCE(desc->tail);
        GEM_BUG_ON(CIRC_SPACE(wq_off, READ_ONCE(desc->head),
                              GUC_WQ_SIZE) < wqi_size);
        GEM_BUG_ON(wq_off & (wqi_size - 1));

        /* WQ starts from the page after doorbell / process_desc */
        wqi = client->vaddr + wq_off + GUC_DB_SIZE;

        if (I915_SELFTEST_ONLY(client->use_nop_wqi)) {
                wqi->header = WQ_TYPE_NOOP | (wqi_len << WQ_LEN_SHIFT);
        } else {
                /* Now fill in the 4-word work queue item */
                wqi->header = WQ_TYPE_INORDER |
                              (wqi_len << WQ_LEN_SHIFT) |
                              (target_engine << WQ_TARGET_SHIFT) |
                              WQ_NO_WCFLUSH_WAIT;
                wqi->context_desc = context_desc;
                wqi->submit_element_info = ring_tail << WQ_RING_TAIL_SHIFT;
                GEM_BUG_ON(ring_tail > WQ_RING_TAIL_MAX);
                wqi->fence_id = fence_id;
        }

        /* Make the update visible to GuC */
        WRITE_ONCE(desc->tail, (wq_off + wqi_size) & (GUC_WQ_SIZE - 1));
}

static void guc_ring_doorbell(struct intel_guc_client *client)
{
        struct guc_doorbell_info *db;
        u32 cookie;

        lockdep_assert_held(&client->wq_lock);

        /* pointer of current doorbell cacheline */
        db = __get_doorbell(client);

        /*
         * We're not expecting the doorbell cookie to change behind our back,
         * we also need to treat 0 as a reserved value.
         */
        cookie = READ_ONCE(db->cookie);
        WARN_ON_ONCE(xchg(&db->cookie, cookie + 1 ?: cookie + 2) != cookie);

        /* XXX: doorbell was lost and need to acquire it again */
        GEM_BUG_ON(db->db_status != GUC_DOORBELL_ENABLED);
}

static void guc_add_request(struct intel_guc *guc, struct i915_request *rq)
{
        struct intel_guc_client *client = guc->execbuf_client;
        struct intel_engine_cs *engine = rq->engine;
        u32 ctx_desc = lower_32_bits(rq->hw_context->lrc_desc);
        u32 ring_tail = intel_ring_set_tail(rq->ring, rq->tail) / sizeof(u64);

        guc_wq_item_append(client, engine->guc_id, ctx_desc,
                           ring_tail, rq->fence.seqno);
        guc_ring_doorbell(client);
}

/*
 * When we're doing submissions using regular execlists backend, writing to
 * ELSP from CPU side is enough to make sure that writes to ringbuffer pages
 * pinned in mappable aperture portion of GGTT are visible to command streamer.
 * Writes done by GuC on our behalf are not guaranteeing such ordering,
 * therefore, to ensure the flush, we're issuing a POSTING READ.
 */
static void flush_ggtt_writes(struct i915_vma *vma)
{
        struct drm_i915_private *i915 = vma->vm->i915;

        if (i915_vma_is_map_and_fenceable(vma))
                intel_uncore_posting_read_fw(&i915->uncore, GUC_STATUS);
}

static void guc_submit(struct intel_engine_cs *engine,
                       struct i915_request **out,
                       struct i915_request **end)
{
        struct intel_guc *guc = &engine->gt->uc.guc;
        struct intel_guc_client *client = guc->execbuf_client;

        spin_lock(&client->wq_lock);

        do {
                struct i915_request *rq = *out++;

                flush_ggtt_writes(rq->ring->vma);
                guc_add_request(guc, rq);
        } while (out != end);

        spin_unlock(&client->wq_lock);
}

static inline int rq_prio(const struct i915_request *rq)
{
        return rq->sched.attr.priority | __NO_PREEMPTION;
}

static struct i915_request *schedule_in(struct i915_request *rq, int idx)
{
        trace_i915_request_in(rq, idx);

        /*
         * Currently we are not tracking the rq->context being inflight
         * (ce->inflight = rq->engine). It is only used by the execlists
         * backend at the moment, a similar counting strategy would be
         * required if we generalise the inflight tracking.
         */

        intel_gt_pm_get(rq->engine->gt);
        return i915_request_get(rq);
}

static void schedule_out(struct i915_request *rq)
{
        trace_i915_request_out(rq);

        intel_gt_pm_put(rq->engine->gt);
        i915_request_put(rq);
}

static void __guc_dequeue(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request **first = execlists->inflight;
        struct i915_request ** const last_port = first + execlists->port_mask;
        struct i915_request *last = first[0];
        struct i915_request **port;
        bool submit = false;
        struct rb_node *rb;

        lockdep_assert_held(&engine->active.lock);

        if (last) {
                if (*++first)
                        return;

                last = NULL;
        }

        /*
         * We write directly into the execlists->inflight queue and don't use
         * the execlists->pending queue, as we don't have a distinct switch
         * event.
         */
        port = first;
        while ((rb = rb_first_cached(&execlists->queue))) {
                struct i915_priolist *p = to_priolist(rb);
                struct i915_request *rq, *rn;
                int i;

                priolist_for_each_request_consume(rq, rn, p, i) {
                        if (last && rq->hw_context != last->hw_context) {
                                if (port == last_port)
                                        goto done;

                                *port = schedule_in(last,
                                                    port - execlists->inflight);
                                port++;
                        }

                        list_del_init(&rq->sched.link);
                        __i915_request_submit(rq);
                        submit = true;
                        last = rq;
                }

                rb_erase_cached(&p->node, &execlists->queue);
                i915_priolist_free(p);
        }
done:
        execlists->queue_priority_hint =
                rb ? to_priolist(rb)->priority : INT_MIN;
        if (submit) {
                *port = schedule_in(last, port - execlists->inflight);
                *++port = NULL;
                guc_submit(engine, first, port);
        }
        execlists->active = execlists->inflight;
}

static void guc_submission_tasklet(unsigned long data)
{
        struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request **port, *rq;
        unsigned long flags;

        spin_lock_irqsave(&engine->active.lock, flags);

        for (port = execlists->inflight; (rq = *port); port++) {
                if (!i915_request_completed(rq))
                        break;

                schedule_out(rq);
        }
        if (port != execlists->inflight) {
                int idx = port - execlists->inflight;
                int rem = ARRAY_SIZE(execlists->inflight) - idx;
                memmove(execlists->inflight, port, rem * sizeof(*port));
        }

        __guc_dequeue(engine);

        spin_unlock_irqrestore(&engine->active.lock, flags);
}

static void guc_reset_prepare(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;

        GEM_TRACE("%s\n", engine->name);

        /*
         * Prevent request submission to the hardware until we have
         * completed the reset in i915_gem_reset_finish(). If a request
         * is completed by one engine, it may then queue a request
         * to a second via its execlists->tasklet *just* as we are
         * calling engine->init_hw() and also writing the ELSP.
         * Turning off the execlists->tasklet until the reset is over
         * prevents the race.
         */
        __tasklet_disable_sync_once(&execlists->tasklet);
}

static void
cancel_port_requests(struct intel_engine_execlists * const execlists)
{
        struct i915_request * const *port, *rq;

        /* Note we are only using the inflight and not the pending queue */

        for (port = execlists->active; (rq = *port); port++)
                schedule_out(rq);
        execlists->active =
                memset(execlists->inflight, 0, sizeof(execlists->inflight));
}

static void guc_reset(struct intel_engine_cs *engine, bool stalled)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request *rq;
        unsigned long flags;

        spin_lock_irqsave(&engine->active.lock, flags);

        cancel_port_requests(execlists);

        /* Push back any incomplete requests for replay after the reset. */
        rq = execlists_unwind_incomplete_requests(execlists);
        if (!rq)
                goto out_unlock;

        if (!i915_request_started(rq))
                stalled = false;

        __i915_request_reset(rq, stalled);
        intel_lr_context_reset(engine, rq->hw_context, rq->head, stalled);

out_unlock:
        spin_unlock_irqrestore(&engine->active.lock, flags);
}

static void guc_cancel_requests(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;
        struct i915_request *rq, *rn;
        struct rb_node *rb;
        unsigned long flags;

        GEM_TRACE("%s\n", engine->name);

        /*
         * Before we call engine->cancel_requests(), we should have exclusive
         * access to the submission state. This is arranged for us by the
         * caller disabling the interrupt generation, the tasklet and other
         * threads that may then access the same state, giving us a free hand
         * to reset state. However, we still need to let lockdep be aware that
         * we know this state may be accessed in hardirq context, so we
         * disable the irq around this manipulation and we want to keep
         * the spinlock focused on its duties and not accidentally conflate
         * coverage to the submission's irq state. (Similarly, although we
         * shouldn't need to disable irq around the manipulation of the
         * submission's irq state, we also wish to remind ourselves that
         * it is irq state.)
         */
        spin_lock_irqsave(&engine->active.lock, flags);

        /* Cancel the requests on the HW and clear the ELSP tracker. */
        cancel_port_requests(execlists);

        /* Mark all executing requests as skipped. */
        list_for_each_entry(rq, &engine->active.requests, sched.link) {
                if (!i915_request_signaled(rq))
                        dma_fence_set_error(&rq->fence, -EIO);

                i915_request_mark_complete(rq);
        }

        /* Flush the queued requests to the timeline list (for retiring). */
        while ((rb = rb_first_cached(&execlists->queue))) {
                struct i915_priolist *p = to_priolist(rb);
                int i;

                priolist_for_each_request_consume(rq, rn, p, i) {
                        list_del_init(&rq->sched.link);
                        __i915_request_submit(rq);
                        dma_fence_set_error(&rq->fence, -EIO);
                        i915_request_mark_complete(rq);
                }

                rb_erase_cached(&p->node, &execlists->queue);
                i915_priolist_free(p);
        }

        /* Remaining _unready_ requests will be nop'ed when submitted */

        execlists->queue_priority_hint = INT_MIN;
        execlists->queue = RB_ROOT_CACHED;

        spin_unlock_irqrestore(&engine->active.lock, flags);
}

static void guc_reset_finish(struct intel_engine_cs *engine)
{
        struct intel_engine_execlists * const execlists = &engine->execlists;

        if (__tasklet_enable(&execlists->tasklet))
                /* And kick in case we missed a new request submission. */
                tasklet_hi_schedule(&execlists->tasklet);

        GEM_TRACE("%s: depth->%d\n", engine->name,
                  atomic_read(&execlists->tasklet.count));
}

/*
 * Everything below here is concerned with setup & teardown, and is
 * therefore not part of the somewhat time-critical batch-submission
 * path of guc_submit() above.
 */

/* Check that a doorbell register is in the expected state */
static bool doorbell_ok(struct intel_guc *guc, u16 db_id)
{
        bool valid;

        GEM_BUG_ON(db_id >= GUC_NUM_DOORBELLS);

        valid = __doorbell_valid(guc, db_id);

        if (test_bit(db_id, guc->doorbell_bitmap) == valid)
                return true;

        DRM_DEBUG_DRIVER("Doorbell %u has unexpected state: valid=%s\n",
                         db_id, yesno(valid));

        return false;
}

static bool guc_verify_doorbells(struct intel_guc *guc)
{
        bool doorbells_ok = true;
        u16 db_id;

        for (db_id = 0; db_id < GUC_NUM_DOORBELLS; ++db_id)
                if (!doorbell_ok(guc, db_id))
                        doorbells_ok = false;

        return doorbells_ok;
}

/**
 * guc_client_alloc() - Allocate an intel_guc_client
 * @guc:        the intel_guc structure
 * @priority:   four levels priority _CRITICAL, _HIGH, _NORMAL and _LOW
 *              The kernel client to replace ExecList submission is created with
 *              NORMAL priority. Priority of a client for scheduler can be HIGH,
 *              while a preemption context can use CRITICAL.
 *
 * Return:      An intel_guc_client object if success, else NULL.
 */
static struct intel_guc_client *
guc_client_alloc(struct intel_guc *guc, u32 priority)
{
        struct intel_guc_client *client;
        struct i915_vma *vma;
        void *vaddr;
        int ret;

        client = kzalloc(sizeof(*client), GFP_KERNEL);
        if (!client)
                return ERR_PTR(-ENOMEM);

        client->guc = guc;
        client->priority = priority;
        client->doorbell_id = GUC_DOORBELL_INVALID;
        spin_lock_init(&client->wq_lock);

        ret = ida_simple_get(&guc->stage_ids, 0, GUC_MAX_STAGE_DESCRIPTORS,
                             GFP_KERNEL);
        if (ret < 0)
                goto err_client;

        client->stage_id = ret;

        /* The first page is doorbell/proc_desc. Two followed pages are wq. */
        vma = intel_guc_allocate_vma(guc, GUC_DB_SIZE + GUC_WQ_SIZE);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto err_id;
        }

        /* We'll keep just the first (doorbell/proc) page permanently kmap'd. */
        client->vma = vma;

        vaddr = i915_gem_object_pin_map(vma->obj, I915_MAP_WB);
        if (IS_ERR(vaddr)) {
                ret = PTR_ERR(vaddr);
                goto err_vma;
        }
        client->vaddr = vaddr;

        ret = reserve_doorbell(client);
        if (ret)
                goto err_vaddr;

        client->doorbell_offset = __select_cacheline(guc);

        /*
         * Since the doorbell only requires a single cacheline, we can save
         * space by putting the application process descriptor in the same
         * page. Use the half of the page that doesn't include the doorbell.
         */
        if (client->doorbell_offset >= (GUC_DB_SIZE / 2))
                client->proc_desc_offset = 0;
        else
                client->proc_desc_offset = (GUC_DB_SIZE / 2);

        DRM_DEBUG_DRIVER("new priority %u client %p: stage_id %u\n",
                         priority, client, client->stage_id);
        DRM_DEBUG_DRIVER("doorbell id %u, cacheline offset 0x%lx\n",
                         client->doorbell_id, client->doorbell_offset);

        return client;

err_vaddr:
        i915_gem_object_unpin_map(client->vma->obj);
err_vma:
        i915_vma_unpin_and_release(&client->vma, 0);
err_id:
        ida_simple_remove(&guc->stage_ids, client->stage_id);
err_client:
        kfree(client);
        return ERR_PTR(ret);
}

static void guc_client_free(struct intel_guc_client *client)
{
        unreserve_doorbell(client);
        i915_vma_unpin_and_release(&client->vma, I915_VMA_RELEASE_MAP);
        ida_simple_remove(&client->guc->stage_ids, client->stage_id);
        kfree(client);
}

static inline bool ctx_save_restore_disabled(struct intel_context *ce)
{
        u32 sr = ce->lrc_reg_state[CTX_CONTEXT_CONTROL + 1];

#define SR_DISABLED \
        _MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT | \
                           CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT)

        return (sr & SR_DISABLED) == SR_DISABLED;

#undef SR_DISABLED
}

static int guc_clients_create(struct intel_guc *guc)
{
        struct intel_guc_client *client;

        GEM_BUG_ON(guc->execbuf_client);

        client = guc_client_alloc(guc, GUC_CLIENT_PRIORITY_KMD_NORMAL);
        if (IS_ERR(client)) {
                DRM_ERROR("Failed to create GuC client for submission!\n");
                return PTR_ERR(client);
        }
        guc->execbuf_client = client;

        return 0;
}

static void guc_clients_destroy(struct intel_guc *guc)
{
        struct intel_guc_client *client;

        client = fetch_and_zero(&guc->execbuf_client);
        if (client)
                guc_client_free(client);
}

static int __guc_client_enable(struct intel_guc_client *client)
{
        int ret;

        guc_proc_desc_init(client);
        guc_stage_desc_init(client);

        ret = create_doorbell(client);
        if (ret)
                goto fail;

        return 0;

fail:
        guc_stage_desc_fini(client);
        guc_proc_desc_fini(client);
        return ret;
}

static void __guc_client_disable(struct intel_guc_client *client)
{
        /*
         * By the time we're here, GuC may have already been reset. if that is
         * the case, instead of trying (in vain) to communicate with it, let's
         * just cleanup the doorbell HW and our internal state.
         */
        if (intel_guc_is_running(client->guc))
                destroy_doorbell(client);
        else
                __fini_doorbell(client);

        guc_stage_desc_fini(client);
        guc_proc_desc_fini(client);
}

static int guc_clients_enable(struct intel_guc *guc)
{
        return __guc_client_enable(guc->execbuf_client);
}

static void guc_clients_disable(struct intel_guc *guc)
{
        if (guc->execbuf_client)
                __guc_client_disable(guc->execbuf_client);
}

/*
 * Set up the memory resources to be shared with the GuC (via the GGTT)
 * at firmware loading time.
 */
int intel_guc_submission_init(struct intel_guc *guc)
{
        int ret;

        if (guc->stage_desc_pool)
                return 0;

        ret = guc_stage_desc_pool_create(guc);
        if (ret)
                return ret;
        /*
         * Keep static analysers happy, let them know that we allocated the
         * vma after testing that it didn't exist earlier.
         */
        GEM_BUG_ON(!guc->stage_desc_pool);

        WARN_ON(!guc_verify_doorbells(guc));
        ret = guc_clients_create(guc);
        if (ret)
                goto err_pool;

        return 0;

err_pool:
        guc_stage_desc_pool_destroy(guc);
        return ret;
}

void intel_guc_submission_fini(struct intel_guc *guc)
{
        guc_clients_destroy(guc);
        WARN_ON(!guc_verify_doorbells(guc));

        if (guc->stage_desc_pool)
                guc_stage_desc_pool_destroy(guc);
}

static void guc_interrupts_capture(struct intel_gt *gt)
{
        struct intel_rps *rps = &gt->i915->gt_pm.rps;
        struct intel_uncore *uncore = gt->uncore;
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        int irqs;

        /* tell all command streamers to forward interrupts (but not vblank)
         * to GuC
         */
        irqs = _MASKED_BIT_ENABLE(GFX_INTERRUPT_STEERING);
        for_each_engine(engine, gt->i915, id)
                ENGINE_WRITE(engine, RING_MODE_GEN7, irqs);

        /* route USER_INTERRUPT to Host, all others are sent to GuC. */
        irqs = GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
               GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT;
        /* These three registers have the same bit definitions */
        intel_uncore_write(uncore, GUC_BCS_RCS_IER, ~irqs);
        intel_uncore_write(uncore, GUC_VCS2_VCS1_IER, ~irqs);
        intel_uncore_write(uncore, GUC_WD_VECS_IER, ~irqs);

        /*
         * The REDIRECT_TO_GUC bit of the PMINTRMSK register directs all
         * (unmasked) PM interrupts to the GuC. All other bits of this
         * register *disable* generation of a specific interrupt.
         *
         * 'pm_intrmsk_mbz' indicates bits that are NOT to be set when
         * writing to the PM interrupt mask register, i.e. interrupts
         * that must not be disabled.
         *
         * If the GuC is handling these interrupts, then we must not let
         * the PM code disable ANY interrupt that the GuC is expecting.
         * So for each ENABLED (0) bit in this register, we must SET the
         * bit in pm_intrmsk_mbz so that it's left enabled for the GuC.
         * GuC needs ARAT expired interrupt unmasked hence it is set in
         * pm_intrmsk_mbz.
         *
         * Here we CLEAR REDIRECT_TO_GUC bit in pm_intrmsk_mbz, which will
         * result in the register bit being left SET!
         */
        rps->pm_intrmsk_mbz |= ARAT_EXPIRED_INTRMSK;
        rps->pm_intrmsk_mbz &= ~GEN8_PMINTR_DISABLE_REDIRECT_TO_GUC;
}

static void guc_interrupts_release(struct intel_gt *gt)
{
        struct intel_rps *rps = &gt->i915->gt_pm.rps;
        struct intel_uncore *uncore = gt->uncore;
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        int irqs;

        /*
         * tell all command streamers NOT to forward interrupts or vblank
         * to GuC.
         */
        irqs = _MASKED_FIELD(GFX_FORWARD_VBLANK_MASK, GFX_FORWARD_VBLANK_NEVER);
        irqs |= _MASKED_BIT_DISABLE(GFX_INTERRUPT_STEERING);
        for_each_engine(engine, gt->i915, id)
                ENGINE_WRITE(engine, RING_MODE_GEN7, irqs);

        /* route all GT interrupts to the host */
        intel_uncore_write(uncore, GUC_BCS_RCS_IER, 0);
        intel_uncore_write(uncore, GUC_VCS2_VCS1_IER, 0);
        intel_uncore_write(uncore, GUC_WD_VECS_IER, 0);

        rps->pm_intrmsk_mbz |= GEN8_PMINTR_DISABLE_REDIRECT_TO_GUC;
        rps->pm_intrmsk_mbz &= ~ARAT_EXPIRED_INTRMSK;
}

static void guc_set_default_submission(struct intel_engine_cs *engine)
{
        /*
         * We inherit a bunch of functions from execlists that we'd like
         * to keep using:
         *
         *    engine->submit_request = execlists_submit_request;
         *    engine->cancel_requests = execlists_cancel_requests;
         *    engine->schedule = execlists_schedule;
         *
         * But we need to override the actual submission backend in order
         * to talk to the GuC.
         */
        intel_execlists_set_default_submission(engine);

        engine->execlists.tasklet.func = guc_submission_tasklet;

        /* do not use execlists park/unpark */
        engine->park = engine->unpark = NULL;

        engine->reset.prepare = guc_reset_prepare;
        engine->reset.reset = guc_reset;
        engine->reset.finish = guc_reset_finish;

        engine->cancel_requests = guc_cancel_requests;

        engine->flags &= ~I915_ENGINE_SUPPORTS_STATS;
        engine->flags |= I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;

        /*
         * For the breadcrumb irq to work we need the interrupts to stay
         * enabled. However, on all platforms on which we'll have support for
         * GuC submission we don't allow disabling the interrupts at runtime, so
         * we're always safe with the current flow.
         */
        GEM_BUG_ON(engine->irq_enable || engine->irq_disable);
}

int intel_guc_submission_enable(struct intel_guc *guc)
{
        struct intel_gt *gt = guc_to_gt(guc);
        struct intel_engine_cs *engine;
        enum intel_engine_id id;
        int err;

        err = i915_inject_load_error(gt->i915, -ENXIO);
        if (err)
                return err;

        /*
         * We're using GuC work items for submitting work through GuC. Since
         * we're coalescing multiple requests from a single context into a
         * single work item prior to assigning it to execlist_port, we can
         * never have more work items than the total number of ports (for all
         * engines). The GuC firmware is controlling the HEAD of work queue,
         * and it is guaranteed that it will remove the work item from the
         * queue before our request is completed.
         */
        BUILD_BUG_ON(ARRAY_SIZE(engine->execlists.inflight) *
                     sizeof(struct guc_wq_item) *
                     I915_NUM_ENGINES > GUC_WQ_SIZE);

        GEM_BUG_ON(!guc->execbuf_client);

        err = guc_clients_enable(guc);
        if (err)
                return err;

        /* Take over from manual control of ELSP (execlists) */
        guc_interrupts_capture(gt);

        for_each_engine(engine, gt->i915, id) {
                engine->set_default_submission = guc_set_default_submission;
                engine->set_default_submission(engine);
        }

        return 0;
}

void intel_guc_submission_disable(struct intel_guc *guc)
{
        struct intel_gt *gt = guc_to_gt(guc);

        GEM_BUG_ON(gt->awake); /* GT should be parked first */

        guc_interrupts_release(gt);
        guc_clients_disable(guc);
}

static bool __guc_submission_support(struct intel_guc *guc)
{
        /* XXX: GuC submission is unavailable for now */
        return false;

        if (!intel_guc_is_supported(guc))
                return false;

        return i915_modparams.enable_guc & ENABLE_GUC_SUBMISSION;
}

void intel_guc_submission_init_early(struct intel_guc *guc)
{
        guc->submission_supported = __guc_submission_support(guc);
}

#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_guc.c"
#endif