On Tue, Sep 17, 2013 at 09:12:46PM -0700, Ben Widawsky wrote:
> On both Ivybridge and Haswell, row remapping information is saved and
> restored with context. This means, we never actually properly supported
> the l3 remapping because our sysfs interface is asynchronous (and not
> tied to any context), and the known faulty HW would be reused by the
> next context to run.
>
> Not that due to the asynchronous nature of the sysfs entry, there is no
> point modifying the registers for the existing context. Instead we set a
> flag for all contexts to load the correct remapping information on the
> next run. Interested clients can use debugfs to determine whether or not
> the row has been remapped.
>
> One could propose at this point that we just do the remapping in the
> kernel. I guess since we have to maintain the sysfs interface anyway,
> I'm not sure how useful it is, and I do like keeping the policy in
> userspace; (it wasn't my original decision to make the
> interface the way it is, so I'm not attached).
>
> v2: Force a context switch when we have a remap on the next switch.
> (Ville)
> Don't let userspace use the interface with disabled contexts.
>
> Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 8 +++++++
> drivers/gpu/drm/i915/i915_drv.h | 1 +
> drivers/gpu/drm/i915/i915_gem_context.c | 22 ++++++++++++++++----
> drivers/gpu/drm/i915/i915_sysfs.c | 37 +++++++++++++--------------------
> 4 files changed, 41 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index ada0950..80bed69 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -145,6 +145,13 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
> seq_printf(m, " (%s)", obj->ring->name);
> }
>
> +static void describe_ctx(struct seq_file *m, struct i915_hw_context *ctx)
> +{
> + seq_putc(m, ctx->is_initialized ? 'I' : 'i');
> + seq_putc(m, ctx->remap_slice ? 'R' : 'r');
> + seq_putc(m, ' ');
> +}
> +
> static int i915_gem_object_list_info(struct seq_file *m, void *data)
> {
> struct drm_info_node *node = (struct drm_info_node *) m->private;
> @@ -1463,6 +1470,7 @@ static int i915_context_status(struct seq_file *m, void *unused)
>
> list_for_each_entry(ctx, &dev_priv->context_list, link) {
> seq_puts(m, "HW context ");
> + describe_ctx(m, ctx);
> for_each_ring(ring, dev_priv, i)
> if (ring->default_context == ctx)
> seq_printf(m, "(default context %s) ", ring->name);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 1795927..015df52 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -601,6 +601,7 @@ struct i915_hw_context {
> struct kref ref;
> int id;
> bool is_initialized;
> + uint8_t remap_slice;
> struct drm_i915_file_private *file_priv;
> struct intel_ring_buffer *ring;
> struct drm_i915_gem_object *obj;
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 2bbdce8..7e138cc 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -140,7 +140,7 @@ create_hw_context(struct drm_device *dev,
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> struct i915_hw_context *ctx;
> - int ret;
> + int ret, i;
>
> ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> if (ctx == NULL)
> @@ -181,6 +181,8 @@ create_hw_context(struct drm_device *dev,
>
> ctx->file_priv = file_priv;
> ctx->id = ret;
> + for (i = 0; i < NUM_L3_SLICES(dev); i++)
> + ctx->remap_slice |= 1 << 1;
^
Still broken.
>
> return ctx;
>
> @@ -396,11 +398,11 @@ static int do_switch(struct i915_hw_context *to)
> struct intel_ring_buffer *ring = to->ring;
> struct i915_hw_context *from = ring->last_context;
> u32 hw_flags = 0;
> - int ret;
> + int ret, i;
>
> BUG_ON(from != NULL && from->obj != NULL && from->obj->pin_count == 0);
>
> - if (from == to)
> + if (from == to && !to->remap_slice)
> return 0;
>
> ret = i915_gem_obj_ggtt_pin(to->obj, CONTEXT_ALIGN, false, false);
> @@ -423,7 +425,7 @@ static int do_switch(struct i915_hw_context *to)
>
> if (!to->is_initialized || is_default_context(to))
> hw_flags |= MI_RESTORE_INHIBIT;
> - else if (WARN_ON_ONCE(from == to)) /* not yet expected */
> + else if (from == to)
> hw_flags |= MI_FORCE_RESTORE;
Hmm. Why do we need to restore actually? Could just leave MI_SET_CONTEXT
to be effectively a nop I think.
>
> ret = mi_set_context(ring, to, hw_flags);
> @@ -432,6 +434,18 @@ static int do_switch(struct i915_hw_context *to)
> return ret;
> }
>
> + for (i = 0; i < MAX_L3_SLICES; i++) {
> + if (!(to->remap_slice & (1<<i)))
> + continue;
> +
> + ret = i915_gem_l3_remap(ring, i);
> + if (!ret) {
> + to->remap_slice &= ~(1<<i);
> + /* If it failed, try again next round */
> + DRM_DEBUG_DRIVER("L3 remapping failed\n");
> + }
The debug message is on the wrong branch.
> + }
> +
> /* The backing object for the context is done after switching to the
> * *next* context. Therefore we cannot retire the previous context until
> * the next context has already started running. In fact, the below code
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index b07bdfb..deb8787 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -118,9 +118,8 @@ i915_l3_read(struct file *filp, struct kobject *kobj,
> struct drm_minor *dminor = container_of(dev, struct drm_minor, kdev);
> struct drm_device *drm_dev = dminor->dev;
> struct drm_i915_private *dev_priv = drm_dev->dev_private;
> - uint32_t misccpctl;
> int slice = (int)(uintptr_t)attr->private;
> - int i, ret;
> + int ret;
>
> count = round_down(count, 4);
>
> @@ -134,26 +133,13 @@ i915_l3_read(struct file *filp, struct kobject *kobj,
> if (ret)
> return ret;
>
> - if (IS_HASWELL(drm_dev)) {
> - if (dev_priv->l3_parity.remap_info[slice])
> - memcpy(buf,
> - dev_priv->l3_parity.remap_info[slice] + (offset/4),
> - count);
> - else
> - memset(buf, 0, count);
> -
> - goto out;
> - }
> -
> - misccpctl = I915_READ(GEN7_MISCCPCTL);
> - I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
> -
> - for (i = 0; i < count; i += 4)
> - *((uint32_t *)(&buf[i])) = I915_READ(GEN7_L3LOG_BASE + offset + i);
> -
> - I915_WRITE(GEN7_MISCCPCTL, misccpctl);
> + if (dev_priv->l3_parity.remap_info[slice])
> + memcpy(buf,
> + dev_priv->l3_parity.remap_info[slice] + (offset/4),
> + count);
> + else
> + memset(buf, 0, count);
>
> -out:
> mutex_unlock(&drm_dev->struct_mutex);
>
> return count;
> @@ -168,6 +154,7 @@ i915_l3_write(struct file *filp, struct kobject *kobj,
> struct drm_minor *dminor = container_of(dev, struct drm_minor, kdev);
> struct drm_device *drm_dev = dminor->dev;
> struct drm_i915_private *dev_priv = drm_dev->dev_private;
> + struct i915_hw_context *ctx;
> u32 *temp = NULL; /* Just here to make handling failures easy */
> int slice = (int)(uintptr_t)attr->private;
> int ret;
> @@ -176,6 +163,9 @@ i915_l3_write(struct file *filp, struct kobject *kobj,
> if (ret)
> return ret;
>
> + if (dev_priv->hw_contexts_disabled)
> + return -ENXIO;
> +
> ret = i915_mutex_lock_interruptible(drm_dev);
> if (ret)
> return ret;
> @@ -204,8 +194,9 @@ i915_l3_write(struct file *filp, struct kobject *kobj,
>
> memcpy(dev_priv->l3_parity.remap_info[slice] + (offset/4), buf, count);
>
> - if (i915_gem_l3_remap(&dev_priv->ring[RCS], slice))
> - count = 0;
> + /* NB: We defer the remapping until we switch to the context */
> + list_for_each_entry(ctx, &dev_priv->context_list, link)
> + ctx->remap_slice |= (1<<slice);
>
> mutex_unlock(&drm_dev->struct_mutex);
>
> --
> 1.8.4
>
> _______________________________________________
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> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Ville Syrjälä
Intel OTC
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