[Intel-gfx] [PATCH 20/27] drm/i915: Remove logical HW ID

Daniele Ceraolo Spurio daniele.ceraolospurio at intel.com
Wed Sep 25 17:59:32 UTC 2019


+ Matt

On 9/25/19 5:41 AM, Tvrtko Ursulin wrote:
> [+ Daniele, I think he might want to have a look at this.]
> 
> On 25/09/2019 11:01, Chris Wilson wrote:
>> With the introduction of ctx->engines[] we allow multiple logical
>> contexts to be used on the same engine (e.g. with virtual engines). Each
>> logical context requires a unique tag in order for context-switching to
>> occur correctly between them.
>>
>> We only need to keep a unique tag for the active lifetime of the
>> context, and for as long as we need to identify that context. The HW
>> uses the tag to determine if it should use a lite-restore (why not the
>> LRCA?) and passes the tag back for various status identifies. The only
>> status we need to track is for OA, so when using perf, we assign the
>> specific context a unique tag.
>>
>> Fixes: 976b55f0e1db ("drm/i915: Allow a context to define its set of 
>> engines")
> 
> Fixes? Why?
> 
>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> ---
>>   drivers/gpu/drm/i915/gem/i915_gem_context.c   | 147 ------------------
>>   drivers/gpu/drm/i915/gem/i915_gem_context.h   |  15 --
>>   .../gpu/drm/i915/gem/i915_gem_context_types.h |  18 ---
>>   .../drm/i915/gem/selftests/i915_gem_context.c |  13 +-
>>   .../gpu/drm/i915/gem/selftests/mock_context.c |   8 -
>>   drivers/gpu/drm/i915/gt/intel_context_types.h |   1 +
>>   drivers/gpu/drm/i915/gt/intel_engine_types.h  |   4 +-
>>   drivers/gpu/drm/i915/gt/intel_lrc.c           |  29 ++--
>>   drivers/gpu/drm/i915/gvt/kvmgt.c              |  17 --
>>   drivers/gpu/drm/i915/i915_debugfs.c           |   3 -
>>   drivers/gpu/drm/i915/i915_gpu_error.c         |   7 +-
>>   drivers/gpu/drm/i915/i915_gpu_error.h         |   1 -
>>   drivers/gpu/drm/i915/i915_perf.c              |  25 ++-
>>   drivers/gpu/drm/i915/i915_trace.h             |  38 ++---
>>   .../gpu/drm/i915/selftests/i915_gem_evict.c   |   4 +-
>>   drivers/gpu/drm/i915/selftests/i915_vma.c     |   2 +-
>>   16 files changed, 48 insertions(+), 284 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c 
>> b/drivers/gpu/drm/i915/gem/i915_gem_context.c
>> index e832238a72e5..4e59b809d901 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
>> @@ -168,97 +168,6 @@ lookup_user_engine(struct i915_gem_context *ctx,
>>       return i915_gem_context_get_engine(ctx, idx);
>>   }
>> -static inline int new_hw_id(struct drm_i915_private *i915, gfp_t gfp)
>> -{
>> -    unsigned int max;
>> -
>> -    lockdep_assert_held(&i915->contexts.mutex);
>> -
>> -    if (INTEL_GEN(i915) >= 12)
>> -        max = GEN12_MAX_CONTEXT_HW_ID;
>> -    else if (INTEL_GEN(i915) >= 11)
>> -        max = GEN11_MAX_CONTEXT_HW_ID;
>> -    else if (USES_GUC_SUBMISSION(i915))
>> -        /*
>> -         * When using GuC in proxy submission, GuC consumes the
>> -         * highest bit in the context id to indicate proxy submission.
>> -         */
>> -        max = MAX_GUC_CONTEXT_HW_ID;
>> -    else
>> -        max = MAX_CONTEXT_HW_ID;
>> -
>> -    return ida_simple_get(&i915->contexts.hw_ida, 0, max, gfp);
>> -}
>> -
>> -static int steal_hw_id(struct drm_i915_private *i915)
>> -{
>> -    struct i915_gem_context *ctx, *cn;
>> -    LIST_HEAD(pinned);
>> -    int id = -ENOSPC;
>> -
>> -    lockdep_assert_held(&i915->contexts.mutex);
>> -
>> -    list_for_each_entry_safe(ctx, cn,
>> -                 &i915->contexts.hw_id_list, hw_id_link) {
>> -        if (atomic_read(&ctx->hw_id_pin_count)) {
>> -            list_move_tail(&ctx->hw_id_link, &pinned);
>> -            continue;
>> -        }
>> -
>> -        GEM_BUG_ON(!ctx->hw_id); /* perma-pinned kernel context */
>> -        list_del_init(&ctx->hw_id_link);
>> -        id = ctx->hw_id;
>> -        break;
>> -    }
>> -
>> -    /*
>> -     * Remember how far we got up on the last repossesion scan, so the
>> -     * list is kept in a "least recently scanned" order.
>> -     */
>> -    list_splice_tail(&pinned, &i915->contexts.hw_id_list);
>> -    return id;
>> -}
>> -
>> -static int assign_hw_id(struct drm_i915_private *i915, unsigned int 
>> *out)
>> -{
>> -    int ret;
>> -
>> -    lockdep_assert_held(&i915->contexts.mutex);
>> -
>> -    /*
>> -     * We prefer to steal/stall ourselves and our users over that of the
>> -     * entire system. That may be a little unfair to our users, and
>> -     * even hurt high priority clients. The choice is whether to oomkill
>> -     * something else, or steal a context id.
>> -     */
>> -    ret = new_hw_id(i915, GFP_KERNEL | __GFP_RETRY_MAYFAIL | 
>> __GFP_NOWARN);
>> -    if (unlikely(ret < 0)) {
>> -        ret = steal_hw_id(i915);
>> -        if (ret < 0) /* once again for the correct errno code */
>> -            ret = new_hw_id(i915, GFP_KERNEL);
>> -        if (ret < 0)
>> -            return ret;
>> -    }
>> -
>> -    *out = ret;
>> -    return 0;
>> -}
>> -
>> -static void release_hw_id(struct i915_gem_context *ctx)
>> -{
>> -    struct drm_i915_private *i915 = ctx->i915;
>> -
>> -    if (list_empty(&ctx->hw_id_link))
>> -        return;
>> -
>> -    mutex_lock(&i915->contexts.mutex);
>> -    if (!list_empty(&ctx->hw_id_link)) {
>> -        ida_simple_remove(&i915->contexts.hw_ida, ctx->hw_id);
>> -        list_del_init(&ctx->hw_id_link);
>> -    }
>> -    mutex_unlock(&i915->contexts.mutex);
>> -}
>> -
>>   static void __free_engines(struct i915_gem_engines *e, unsigned int 
>> count)
>>   {
>>       while (count--) {
>> @@ -313,8 +222,6 @@ static void i915_gem_context_free(struct 
>> i915_gem_context *ctx)
>>       lockdep_assert_held(&ctx->i915->drm.struct_mutex);
>>       GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
>> -    release_hw_id(ctx);
>> -
>>       free_engines(rcu_access_pointer(ctx->engines));
>>       mutex_destroy(&ctx->engines_mutex);
>> @@ -459,12 +366,6 @@ static void context_close(struct i915_gem_context 
>> *ctx)
>>       ctx->file_priv = ERR_PTR(-EBADF);
>> -    /*
>> -     * This context will never again be assinged to HW, so we can
>> -     * reuse its ID for the next context.
>> -     */
>> -    release_hw_id(ctx);
>> -
>>       /*
>>        * The LUT uses the VMA as a backpointer to unref the object,
>>        * so we need to clear the LUT before we close all the VMA (inside
>> @@ -507,7 +408,6 @@ __create_context(struct drm_i915_private *i915)
>>       RCU_INIT_POINTER(ctx->engines, e);
>>       INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
>> -    INIT_LIST_HEAD(&ctx->hw_id_link);
>>       /* NB: Mark all slices as needing a remap so that when the 
>> context first
>>        * loads it will restore whatever remap state already exists. If 
>> there
>> @@ -676,18 +576,11 @@ struct i915_gem_context *
>>   i915_gem_context_create_kernel(struct drm_i915_private *i915, int prio)
>>   {
>>       struct i915_gem_context *ctx;
>> -    int err;
>>       ctx = i915_gem_create_context(i915, 0);
>>       if (IS_ERR(ctx))
>>           return ctx;
>> -    err = i915_gem_context_pin_hw_id(ctx);
>> -    if (err) {
>> -        destroy_kernel_context(&ctx);
>> -        return ERR_PTR(err);
>> -    }
>> -
>>       i915_gem_context_clear_bannable(ctx);
>>       i915_gem_context_set_persistence(ctx);
>>       ctx->sched.priority = I915_USER_PRIORITY(prio);
>> @@ -727,15 +620,6 @@ int i915_gem_contexts_init(struct 
>> drm_i915_private *dev_priv)
>>           DRM_ERROR("Failed to create default global context\n");
>>           return PTR_ERR(ctx);
>>       }
>> -    /*
>> -     * For easy recognisablity, we want the kernel context to be 0 
>> and then
>> -     * all user contexts will have non-zero hw_id. Kernel contexts are
>> -     * permanently pinned, so that we never suffer a stall and can
>> -     * use them from any allocation context (e.g. for evicting other
>> -     * contexts and from inside the shrinker).
>> -     */
>> -    GEM_BUG_ON(ctx->hw_id);
>> -    GEM_BUG_ON(!atomic_read(&ctx->hw_id_pin_count));
>>       dev_priv->kernel_context = ctx;
>>       DRM_DEBUG_DRIVER("%s context support initialized\n",
>> @@ -749,10 +633,6 @@ void i915_gem_contexts_fini(struct 
>> drm_i915_private *i915)
>>       lockdep_assert_held(&i915->drm.struct_mutex);
>>       destroy_kernel_context(&i915->kernel_context);
>> -
>> -    /* Must free all deferred contexts (via flush_workqueue) first */
>> -    GEM_BUG_ON(!list_empty(&i915->contexts.hw_id_list));
>> -    ida_destroy(&i915->contexts.hw_ida);
>>   }
>>   static int context_idr_cleanup(int id, void *p, void *data)
>> @@ -2438,33 +2318,6 @@ int i915_gem_context_reset_stats_ioctl(struct 
>> drm_device *dev,
>>       return ret;
>>   }
>> -int __i915_gem_context_pin_hw_id(struct i915_gem_context *ctx)
>> -{
>> -    struct drm_i915_private *i915 = ctx->i915;
>> -    int err = 0;
>> -
>> -    mutex_lock(&i915->contexts.mutex);
>> -
>> -    GEM_BUG_ON(i915_gem_context_is_closed(ctx));
>> -
>> -    if (list_empty(&ctx->hw_id_link)) {
>> -        GEM_BUG_ON(atomic_read(&ctx->hw_id_pin_count));
>> -
>> -        err = assign_hw_id(i915, &ctx->hw_id);
>> -        if (err)
>> -            goto out_unlock;
>> -
>> -        list_add_tail(&ctx->hw_id_link, &i915->contexts.hw_id_list);
>> -    }
>> -
>> -    GEM_BUG_ON(atomic_read(&ctx->hw_id_pin_count) == ~0u);
>> -    atomic_inc(&ctx->hw_id_pin_count);
>> -
>> -out_unlock:
>> -    mutex_unlock(&i915->contexts.mutex);
>> -    return err;
>> -}
>> -
>>   /* GEM context-engines iterator: for_each_gem_engine() */
>>   struct intel_context *
>>   i915_gem_engines_iter_next(struct i915_gem_engines_iter *it)
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.h 
>> b/drivers/gpu/drm/i915/gem/i915_gem_context.h
>> index e0f5b6c6a331..1b0df53436cf 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.h
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.h
>> @@ -127,21 +127,6 @@ i915_gem_context_clear_user_engines(struct 
>> i915_gem_context *ctx)
>>       clear_bit(CONTEXT_USER_ENGINES, &ctx->flags);
>>   }
>> -int __i915_gem_context_pin_hw_id(struct i915_gem_context *ctx);
>> -static inline int i915_gem_context_pin_hw_id(struct i915_gem_context 
>> *ctx)
>> -{
>> -    if (atomic_inc_not_zero(&ctx->hw_id_pin_count))
>> -        return 0;
>> -
>> -    return __i915_gem_context_pin_hw_id(ctx);
>> -}
>> -
>> -static inline void i915_gem_context_unpin_hw_id(struct 
>> i915_gem_context *ctx)
>> -{
>> -    GEM_BUG_ON(atomic_read(&ctx->hw_id_pin_count) == 0u);
>> -    atomic_dec(&ctx->hw_id_pin_count);
>> -}
>> -
>>   static inline bool i915_gem_context_is_kernel(struct 
>> i915_gem_context *ctx)
>>   {
>>       return !ctx->file_priv;
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h 
>> b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
>> index daf1ea5075a6..6419da7c9f90 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
>> @@ -148,24 +148,6 @@ struct i915_gem_context {
>>   #define CONTEXT_FORCE_SINGLE_SUBMISSION    2
>>   #define CONTEXT_USER_ENGINES        3
>> -    /**
>> -     * @hw_id: - unique identifier for the context
>> -     *
>> -     * The hardware needs to uniquely identify the context for a few
>> -     * functions like fault reporting, PASID, scheduling. The
>> -     * &drm_i915_private.context_hw_ida is used to assign a unqiue
>> -     * id for the lifetime of the context.
>> -     *
>> -     * @hw_id_pin_count: - number of times this context had been pinned
>> -     * for use (should be, at most, once per engine).
>> -     *
>> -     * @hw_id_link: - all contexts with an assigned id are tracked
>> -     * for possible repossession.
>> -     */
>> -    unsigned int hw_id;
>> -    atomic_t hw_id_pin_count;
>> -    struct list_head hw_id_link;
>> -
>>       struct mutex mutex;
>>       struct i915_sched_attr sched;
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c 
>> b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
>> index b39224ed3817..a8a9293f4ac6 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c
>> @@ -446,9 +446,9 @@ static int igt_ctx_exec(void *arg)
>>               err = gpu_fill(ce, obj, dw);
>>               if (err) {
>> -                pr_err("Failed to fill dword %lu [%lu/%lu] with gpu 
>> (%s) in ctx %u [full-ppgtt? %s], err=%d\n",
>> +                pr_err("Failed to fill dword %lu [%lu/%lu] with gpu 
>> (%s) [full-ppgtt? %s], err=%d\n",
>>                          ndwords, dw, max_dwords(obj),
>> -                       engine->name, ctx->hw_id,
>> +                       engine->name,
>>                          yesno(!!ctx->vm), err);
>>                   intel_context_put(ce);
>>                   kernel_context_close(ctx);
>> @@ -584,9 +584,9 @@ static int igt_shared_ctx_exec(void *arg)
>>               err = gpu_fill(ce, obj, dw);
>>               if (err) {
>> -                pr_err("Failed to fill dword %lu [%lu/%lu] with gpu 
>> (%s) in ctx %u [full-ppgtt? %s], err=%d\n",
>> +                pr_err("Failed to fill dword %lu [%lu/%lu] with gpu 
>> (%s) [full-ppgtt? %s], err=%d\n",
>>                          ndwords, dw, max_dwords(obj),
>> -                       engine->name, ctx->hw_id,
>> +                       engine->name,
>>                          yesno(!!ctx->vm), err);
>>                   intel_context_put(ce);
>>                   kernel_context_close(ctx);
>> @@ -1168,10 +1168,9 @@ static int igt_ctx_readonly(void *arg)
>>               err = gpu_fill(ce, obj, dw);
>>               if (err) {
>> -                pr_err("Failed to fill dword %lu [%lu/%lu] with gpu 
>> (%s) in ctx %u [full-ppgtt? %s], err=%d\n",
>> +                pr_err("Failed to fill dword %lu [%lu/%lu] with gpu 
>> (%s) [full-ppgtt? %s], err=%d\n",
>>                          ndwords, dw, max_dwords(obj),
>> -                       ce->engine->name, ctx->hw_id,
>> -                       yesno(!!ctx->vm), err);
>> +                       ce->engine->name, yesno(!!ctx->vm), err);
>>                   i915_gem_context_unlock_engines(ctx);
>>                   goto out_unlock;
>>               }
>> diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c 
>> b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
>> index 0d1a275ec316..ebc46f098561 100644
>> --- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c
>> +++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
>> @@ -13,7 +13,6 @@ mock_context(struct drm_i915_private *i915,
>>   {
>>       struct i915_gem_context *ctx;
>>       struct i915_gem_engines *e;
>> -    int ret;
>>       ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
>>       if (!ctx)
>> @@ -32,13 +31,8 @@ mock_context(struct drm_i915_private *i915,
>>       RCU_INIT_POINTER(ctx->engines, e);
>>       INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
>> -    INIT_LIST_HEAD(&ctx->hw_id_link);
>>       mutex_init(&ctx->mutex);
>> -    ret = i915_gem_context_pin_hw_id(ctx);
>> -    if (ret < 0)
>> -        goto err_engines;
>> -
>>       if (name) {
>>           struct i915_ppgtt *ppgtt;
>> @@ -56,8 +50,6 @@ mock_context(struct drm_i915_private *i915,
>>       return ctx;
>> -err_engines:
>> -    free_engines(rcu_access_pointer(ctx->engines));
>>   err_free:
>>       kfree(ctx);
>>       return NULL;
>> diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h 
>> b/drivers/gpu/drm/i915/gt/intel_context_types.h
>> index bf9cedfccbf0..6959b05ae5f8 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_context_types.h
>> +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
>> @@ -58,6 +58,7 @@ struct intel_context {
>>       u32 *lrc_reg_state;
>>       u64 lrc_desc;
>> +    u32 tag; /* cookie passed to HW to track this context on 
>> submission */
>>       unsigned int active_count; /* protected by timeline->mutex */
>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h 
>> b/drivers/gpu/drm/i915/gt/intel_engine_types.h
>> index da4b45aa84b1..7bce176e696c 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
>> @@ -296,10 +296,12 @@ struct intel_engine_cs {
>>       u8 uabi_class;
>>       u8 uabi_instance;
>> +    u32 uabi_capabilities;
>>       u32 context_size;
>>       u32 mmio_base;
>> -    u32 uabi_capabilities;
>> +    unsigned int context_tag;
>> +#define NUM_CONTEXT_TAG (256)
> 
> AFAICT this define now defines how deep ELSP we can have before we start 
> getting hard to debug problems. GuC angle needs considering here.
> 
> Can we add some asserts somewhere to express the relationship?
> 
> And a comment here explaining this, or with the assert.
> 
>>       struct rb_node uabi_node;
>> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c 
>> b/drivers/gpu/drm/i915/gt/intel_lrc.c
>> index 0ea2f4d7dc43..af79b8d70800 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
>> @@ -433,12 +433,8 @@ assert_priority_queue(const struct i915_request 
>> *prev,
>>   static u64
>>   lrc_descriptor(struct intel_context *ce, struct intel_engine_cs 
>> *engine)
>>   {
>> -    struct i915_gem_context *ctx = ce->gem_context;
>>       u64 desc;
>> -    BUILD_BUG_ON(MAX_CONTEXT_HW_ID > (BIT(GEN8_CTX_ID_WIDTH)));
>> -    BUILD_BUG_ON(GEN11_MAX_CONTEXT_HW_ID > 
>> (BIT(GEN11_SW_CTX_ID_WIDTH)));
>> -
>>       desc = INTEL_LEGACY_32B_CONTEXT;
>>       if (i915_vm_is_4lvl(ce->vm))
>>           desc = INTEL_LEGACY_64B_CONTEXT;
>> @@ -456,20 +452,11 @@ lrc_descriptor(struct intel_context *ce, struct 
>> intel_engine_cs *engine)
>>        * anything below.
>>        */
>>       if (INTEL_GEN(engine->i915) >= 11) {
>> -        GEM_BUG_ON(ctx->hw_id >= BIT(GEN11_SW_CTX_ID_WIDTH));
>> -        desc |= (u64)ctx->hw_id << GEN11_SW_CTX_ID_SHIFT;
>> -                                /* bits 37-47 */
>> -
>>           desc |= (u64)engine->instance << GEN11_ENGINE_INSTANCE_SHIFT;
>>                                   /* bits 48-53 */
>> -        /* TODO: decide what to do with SW counter (bits 55-60) */
>> -
>>           desc |= (u64)engine->class << GEN11_ENGINE_CLASS_SHIFT;
>>                                   /* bits 61-63 */
>> -    } else {
>> -        GEM_BUG_ON(ctx->hw_id >= BIT(GEN8_CTX_ID_WIDTH));
>> -        desc |= (u64)ctx->hw_id << GEN8_CTX_ID_SHIFT;    /* bits 
>> 32-52 */
>>       }
>>       return desc;
>> @@ -978,6 +965,15 @@ __execlists_schedule_in(struct i915_request *rq)
>>       intel_context_get(ce);
>> +    if (ce->tag) {
>> +        ce->lrc_desc |= (u64)ce->tag << 32;
>> +    } else {
>> +        ce->lrc_desc &= ~GENMASK_ULL(47, 37);
>> +        ce->lrc_desc |=
>> +            (u64)(engine->context_tag++ % NUM_CONTEXT_TAG) <<
>> +            GEN11_SW_CTX_ID_SHIFT;
>> +    }
> 
> So hw id is valid only while context is in ELSP and it changes with 
> every submission except in the OA case?
> 
> Shifts and masks look dodgy. For >= gen11 the current code has the hw_id 
> in [37, 42], otherwise [32, 52]. This patch does not seem to handle the 
> differences between gens.
> 
>> +
>>       intel_gt_pm_get(engine->gt);
>>       execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_IN);
>>       intel_engine_context_in(engine);
>> @@ -2224,7 +2220,6 @@ static void execlists_context_unpin(struct 
>> intel_context *ce)
>>       check_redzone((void *)ce->lrc_reg_state - LRC_STATE_PN * PAGE_SIZE,
>>                 ce->engine);
>> -    i915_gem_context_unpin_hw_id(ce->gem_context);
>>       i915_gem_object_unpin_map(ce->state->obj);
>>       intel_ring_reset(ce->ring, ce->ring->tail);
>>   }
>> @@ -2274,18 +2269,12 @@ __execlists_context_pin(struct intel_context *ce,
>>           goto unpin_active;
>>       }
>> -    ret = i915_gem_context_pin_hw_id(ce->gem_context);
>> -    if (ret)
>> -        goto unpin_map;
>> -
>>       ce->lrc_desc = lrc_descriptor(ce, engine);
>>       ce->lrc_reg_state = vaddr + LRC_STATE_PN * PAGE_SIZE;
>>       __execlists_update_reg_state(ce, engine);
>>       return 0;
>> -unpin_map:
>> -    i915_gem_object_unpin_map(ce->state->obj);
>>   unpin_active:
>>       intel_context_active_release(ce);
>>   err:
>> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c 
>> b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> index 343d79c1cb7e..04a5a0d90823 100644
>> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
>> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
>> @@ -1564,27 +1564,10 @@ vgpu_id_show(struct device *dev, struct 
>> device_attribute *attr,
>>       return sprintf(buf, "\n");
>>   }
>> -static ssize_t
>> -hw_id_show(struct device *dev, struct device_attribute *attr,
>> -       char *buf)
>> -{
>> -    struct mdev_device *mdev = mdev_from_dev(dev);
>> -
>> -    if (mdev) {
>> -        struct intel_vgpu *vgpu = (struct intel_vgpu *)
>> -            mdev_get_drvdata(mdev);
>> -        return sprintf(buf, "%u\n",
>> -                   vgpu->submission.shadow[0]->gem_context->hw_id);
>> -    }
>> -    return sprintf(buf, "\n");
>> -}
>> -
>>   static DEVICE_ATTR_RO(vgpu_id);
>> -static DEVICE_ATTR_RO(hw_id);
>>   static struct attribute *intel_vgpu_attrs[] = {
>>       &dev_attr_vgpu_id.attr,
>> -    &dev_attr_hw_id.attr,
>>       NULL
>>   };
>> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
>> b/drivers/gpu/drm/i915/i915_debugfs.c
>> index fd41505d52ec..8caaa446490f 100644
>> --- a/drivers/gpu/drm/i915/i915_debugfs.c
>> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
>> @@ -1504,9 +1504,6 @@ static int i915_context_status(struct seq_file 
>> *m, void *unused)
>>           struct intel_context *ce;
>>           seq_puts(m, "HW context ");
>> -        if (!list_empty(&ctx->hw_id_link))
>> -            seq_printf(m, "%x [pin %u]", ctx->hw_id,
>> -                   atomic_read(&ctx->hw_id_pin_count));
>>           if (ctx->pid) {
>>               struct task_struct *task;
>> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c 
>> b/drivers/gpu/drm/i915/i915_gpu_error.c
>> index a86d28bda6dd..47239df653f2 100644
>> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
>> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
>> @@ -471,9 +471,9 @@ static void error_print_context(struct 
>> drm_i915_error_state_buf *m,
>>                   const char *header,
>>                   const struct drm_i915_error_context *ctx)
>>   {
>> -    err_printf(m, "%s%s[%d] hw_id %d, prio %d, guilty %d active %d\n",
>> -           header, ctx->comm, ctx->pid, ctx->hw_id,
>> -           ctx->sched_attr.priority, ctx->guilty, ctx->active);
>> +    err_printf(m, "%s%s[%d] prio %d, guilty %d active %d\n",
>> +           header, ctx->comm, ctx->pid, ctx->sched_attr.priority,
>> +           ctx->guilty, ctx->active);
>>   }
>>   static void error_print_engine(struct drm_i915_error_state_buf *m,
>> @@ -1262,7 +1262,6 @@ static bool record_context(struct 
>> drm_i915_error_context *e,
>>           rcu_read_unlock();
>>       }
>> -    e->hw_id = ctx->hw_id;
>>       e->sched_attr = ctx->sched;
>>       e->guilty = atomic_read(&ctx->guilty_count);
>>       e->active = atomic_read(&ctx->active_count);
>> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h 
>> b/drivers/gpu/drm/i915/i915_gpu_error.h
>> index caaed5093d95..4dc36d6ee3a2 100644
>> --- a/drivers/gpu/drm/i915/i915_gpu_error.h
>> +++ b/drivers/gpu/drm/i915/i915_gpu_error.h
>> @@ -117,7 +117,6 @@ struct i915_gpu_state {
>>           struct drm_i915_error_context {
>>               char comm[TASK_COMM_LEN];
>>               pid_t pid;
>> -            u32 hw_id;
>>               int active;
>>               int guilty;
>>               struct i915_sched_attr sched_attr;
>> diff --git a/drivers/gpu/drm/i915/i915_perf.c 
>> b/drivers/gpu/drm/i915/i915_perf.c
>> index 80055501eccb..d36ba248d438 100644
>> --- a/drivers/gpu/drm/i915/i915_perf.c
>> +++ b/drivers/gpu/drm/i915/i915_perf.c
>> @@ -1283,22 +1283,15 @@ static int oa_get_render_ctx_id(struct 
>> i915_perf_stream *stream)
>>           } else {
>>               stream->specific_ctx_id_mask =
>>                   (1U << GEN8_CTX_ID_WIDTH) - 1;
>> -            stream->specific_ctx_id =
>> -                upper_32_bits(ce->lrc_desc);
>> -            stream->specific_ctx_id &=
>> -                stream->specific_ctx_id_mask;
>> +            stream->specific_ctx_id = stream->specific_ctx_id_mask;
>>           }
>>           break;
>>       case 11:
>>       case 12: {
>>           stream->specific_ctx_id_mask =
>> -            ((1U << GEN11_SW_CTX_ID_WIDTH) - 1) << 
>> (GEN11_SW_CTX_ID_SHIFT - 32) |
>> -            ((1U << GEN11_ENGINE_INSTANCE_WIDTH) - 1) << 
>> (GEN11_ENGINE_INSTANCE_SHIFT - 32) |
>> -            ((1 << GEN11_ENGINE_CLASS_WIDTH) - 1) << 
>> (GEN11_ENGINE_CLASS_SHIFT - 32);
>> -        stream->specific_ctx_id = upper_32_bits(ce->lrc_desc);
>> -        stream->specific_ctx_id &=
>> -            stream->specific_ctx_id_mask;
>> +            ((1U << GEN11_SW_CTX_ID_WIDTH) - 1) << 
>> (GEN11_SW_CTX_ID_SHIFT - 32);
>> +        stream->specific_ctx_id = stream->specific_ctx_id_mask;
>>           break;
>>       }
>> @@ -1306,6 +1299,8 @@ static int oa_get_render_ctx_id(struct 
>> i915_perf_stream *stream)
>>           MISSING_CASE(INTEL_GEN(i915));
>>       }
>> +    ce->tag = stream->specific_ctx_id_mask;
>> +
>>       DRM_DEBUG_DRIVER("filtering on ctx_id=0x%x ctx_id_mask=0x%x\n",
>>                stream->specific_ctx_id,
>>                stream->specific_ctx_id_mask);
>> @@ -1324,12 +1319,14 @@ static void oa_put_render_ctx_id(struct 
>> i915_perf_stream *stream)
>>   {
>>       struct intel_context *ce;
>> -    stream->specific_ctx_id = INVALID_CTX_ID;
>> -    stream->specific_ctx_id_mask = 0;
>> -
>>       ce = fetch_and_zero(&stream->pinned_ctx);
>> -    if (ce)
>> +    if (ce) {
>> +        ce->tag = 0;
>>           intel_context_unpin(ce);
>> +    }
>> +
>> +    stream->specific_ctx_id = INVALID_CTX_ID;
>> +    stream->specific_ctx_id_mask = 0;
> 
> OA hunks looks dodgy as well. ce->tag is set to 
> stream->specific_ctx_id_mask while I think it should be id. Furthermore 
> id is assigned from mask which is fixed and not unique for different 
> contexts.
> 
>>   }
>>   static void
>> diff --git a/drivers/gpu/drm/i915/i915_trace.h 
>> b/drivers/gpu/drm/i915/i915_trace.h
>> index 24f2944da09d..1f2cf6cfafb5 100644
>> --- a/drivers/gpu/drm/i915/i915_trace.h
>> +++ b/drivers/gpu/drm/i915/i915_trace.h
>> @@ -665,7 +665,6 @@ TRACE_EVENT(i915_request_queue,
>>           TP_STRUCT__entry(
>>                    __field(u32, dev)
>> -                 __field(u32, hw_id)
>>                    __field(u64, ctx)
>>                    __field(u16, class)
>>                    __field(u16, instance)
>> @@ -675,7 +674,6 @@ TRACE_EVENT(i915_request_queue,
>>           TP_fast_assign(
>>                  __entry->dev = rq->i915->drm.primary->index;
>> -               __entry->hw_id = rq->gem_context->hw_id;
>>                  __entry->class = rq->engine->uabi_class;
>>                  __entry->instance = rq->engine->uabi_instance;
>>                  __entry->ctx = rq->fence.context;
>> @@ -683,10 +681,9 @@ TRACE_EVENT(i915_request_queue,
>>                  __entry->flags = flags;
>>                  ),
>> -        TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, 
>> seqno=%u, flags=0x%x",
>> +        TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u, 
>> flags=0x%x",
>>                 __entry->dev, __entry->class, __entry->instance,
>> -              __entry->hw_id, __entry->ctx, __entry->seqno,
>> -              __entry->flags)
>> +              __entry->ctx, __entry->seqno, __entry->flags)
>>   );
>>   DECLARE_EVENT_CLASS(i915_request,
>> @@ -695,7 +692,6 @@ DECLARE_EVENT_CLASS(i915_request,
>>           TP_STRUCT__entry(
>>                    __field(u32, dev)
>> -                 __field(u32, hw_id)
>>                    __field(u64, ctx)
>>                    __field(u16, class)
>>                    __field(u16, instance)
>> @@ -704,16 +700,15 @@ DECLARE_EVENT_CLASS(i915_request,
>>           TP_fast_assign(
>>                  __entry->dev = rq->i915->drm.primary->index;
>> -               __entry->hw_id = rq->gem_context->hw_id;
>>                  __entry->class = rq->engine->uabi_class;
>>                  __entry->instance = rq->engine->uabi_instance;
>>                  __entry->ctx = rq->fence.context;
>>                  __entry->seqno = rq->fence.seqno;
>>                  ),
>> -        TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, seqno=%u",
>> +        TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u",
>>                 __entry->dev, __entry->class, __entry->instance,
>> -              __entry->hw_id, __entry->ctx, __entry->seqno)
>> +              __entry->ctx, __entry->seqno)
>>   );
>>   DEFINE_EVENT(i915_request, i915_request_add,
>> @@ -738,7 +733,6 @@ TRACE_EVENT(i915_request_in,
>>           TP_STRUCT__entry(
>>                    __field(u32, dev)
>> -                 __field(u32, hw_id)
>>                    __field(u64, ctx)
>>                    __field(u16, class)
>>                    __field(u16, instance)
>> @@ -749,7 +743,6 @@ TRACE_EVENT(i915_request_in,
>>           TP_fast_assign(
>>                  __entry->dev = rq->i915->drm.primary->index;
>> -               __entry->hw_id = rq->gem_context->hw_id;
>>                  __entry->class = rq->engine->uabi_class;
>>                  __entry->instance = rq->engine->uabi_instance;
>>                  __entry->ctx = rq->fence.context;
>> @@ -758,9 +751,9 @@ TRACE_EVENT(i915_request_in,
>>                  __entry->port = port;
>>                  ),
>> -        TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, 
>> seqno=%u, prio=%u, port=%u",
>> +        TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u, prio=%u, 
>> port=%u",
>>                 __entry->dev, __entry->class, __entry->instance,
>> -              __entry->hw_id, __entry->ctx, __entry->seqno,
>> +              __entry->ctx, __entry->seqno,
>>                 __entry->prio, __entry->port)
>>   );
>> @@ -770,7 +763,6 @@ TRACE_EVENT(i915_request_out,
>>           TP_STRUCT__entry(
>>                    __field(u32, dev)
>> -                 __field(u32, hw_id)
>>                    __field(u64, ctx)
>>                    __field(u16, class)
>>                    __field(u16, instance)
>> @@ -780,7 +772,6 @@ TRACE_EVENT(i915_request_out,
>>           TP_fast_assign(
>>                  __entry->dev = rq->i915->drm.primary->index;
>> -               __entry->hw_id = rq->gem_context->hw_id;
>>                  __entry->class = rq->engine->uabi_class;
>>                  __entry->instance = rq->engine->uabi_instance;
>>                  __entry->ctx = rq->fence.context;
>> @@ -788,10 +779,9 @@ TRACE_EVENT(i915_request_out,
>>                  __entry->completed = i915_request_completed(rq);
>>                  ),
>> -            TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, 
>> seqno=%u, completed?=%u",
>> +            TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u, 
>> completed?=%u",
>>                     __entry->dev, __entry->class, __entry->instance,
>> -                  __entry->hw_id, __entry->ctx, __entry->seqno,
>> -                  __entry->completed)
>> +                  __entry->ctx, __entry->seqno, __entry->completed)
>>   );
>>   #else
>> @@ -829,7 +819,6 @@ TRACE_EVENT(i915_request_wait_begin,
>>           TP_STRUCT__entry(
>>                    __field(u32, dev)
>> -                 __field(u32, hw_id)
>>                    __field(u64, ctx)
>>                    __field(u16, class)
>>                    __field(u16, instance)
>> @@ -845,7 +834,6 @@ TRACE_EVENT(i915_request_wait_begin,
>>            */
>>           TP_fast_assign(
>>                  __entry->dev = rq->i915->drm.primary->index;
>> -               __entry->hw_id = rq->gem_context->hw_id;
>>                  __entry->class = rq->engine->uabi_class;
>>                  __entry->instance = rq->engine->uabi_instance;
>>                  __entry->ctx = rq->fence.context;
>> @@ -853,9 +841,9 @@ TRACE_EVENT(i915_request_wait_begin,
>>                  __entry->flags = flags;
>>                  ),
>> -        TP_printk("dev=%u, engine=%u:%u, hw_id=%u, ctx=%llu, 
>> seqno=%u, flags=0x%x",
>> +        TP_printk("dev=%u, engine=%u:%u, ctx=%llu, seqno=%u, 
>> flags=0x%x",
>>                 __entry->dev, __entry->class, __entry->instance,
>> -              __entry->hw_id, __entry->ctx, __entry->seqno,
>> +              __entry->ctx, __entry->seqno,
>>                 __entry->flags)
>>   );
>> @@ -958,19 +946,17 @@ DECLARE_EVENT_CLASS(i915_context,
>>       TP_STRUCT__entry(
>>               __field(u32, dev)
>>               __field(struct i915_gem_context *, ctx)
>> -            __field(u32, hw_id)
>>               __field(struct i915_address_space *, vm)
>>       ),
>>       TP_fast_assign(
>>               __entry->dev = ctx->i915->drm.primary->index;
>>               __entry->ctx = ctx;
>> -            __entry->hw_id = ctx->hw_id;
>>               __entry->vm = ctx->vm;
>>       ),
>> -    TP_printk("dev=%u, ctx=%p, ctx_vm=%p, hw_id=%u",
>> -          __entry->dev, __entry->ctx, __entry->vm, __entry->hw_id)
>> +    TP_printk("dev=%u, ctx=%p, ctx_vm=%p",
>> +          __entry->dev, __entry->ctx, __entry->vm)
>>   )
>>   DEFINE_EVENT(i915_context, i915_context_create,
>> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_evict.c 
>> b/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
>> index 52d2df843148..f39f0282e78c 100644
>> --- a/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
>> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_evict.c
>> @@ -491,8 +491,8 @@ static int igt_evict_contexts(void *arg)
>>               if (IS_ERR(rq)) {
>>                   /* When full, fail_if_busy will trigger EBUSY */
>>                   if (PTR_ERR(rq) != -EBUSY) {
>> -                    pr_err("Unexpected error from request alloc (ctx 
>> hw id %u, on %s): %d\n",
>> -                           ctx->hw_id, engine->name,
>> +                    pr_err("Unexpected error from request alloc (on 
>> %s): %d\n",
>> +                           engine->name,
>>                              (int)PTR_ERR(rq));
>>                       err = PTR_ERR(rq);
>>                   }
>> diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c 
>> b/drivers/gpu/drm/i915/selftests/i915_vma.c
>> index 1c9db08f7c28..ac1ff558eb90 100644
>> --- a/drivers/gpu/drm/i915/selftests/i915_vma.c
>> +++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
>> @@ -170,7 +170,7 @@ static int igt_vma_create(void *arg)
>>           }
>>           nc = 0;
>> -        for_each_prime_number(num_ctx, MAX_CONTEXT_HW_ID) {
>> +        for_each_prime_number(num_ctx, 2 * NUM_CONTEXT_TAG) {
>>               for (; nc < num_ctx; nc++) {
>>                   ctx = mock_context(i915, "mock");
>>                   if (!ctx)
>>
> 
> Unless I am missing something I see this patch as simplification and not 
> a fix. If we can get away with it in the GuC world then it's quite a big 
> simplification so it's fine by me.

The GuC will require a fixed ID per intel_context for the whole time the 
context is in use/pinned. The GUC IDs are a global list (i.e. all 
engines share it) with 64k entries, so the logic to assign them is going 
to be a bit different and most likely confined to the guc 
context_pin/unpin callbacks, but we might bring back some of the 
low-level ID management logic that has been removed in this patch.

An ID at the gem_context level definitely doesn't help on the guc side, so:

Acked-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>

Daniele

> 
> Regards,
> 
> Tvrtko


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