On 26/05/2021 15:14, Tvrtko Ursulin wrote:
From: Chris Wilson <[email protected]>

Only perform the domain transition under the object lock, and push the
required waits to outside the lock.

v2 (Tvrtko):
  * Rebase.

Signed-off-by: Chris Wilson <[email protected]>
Reviewed-by: Matthew Auld <[email protected]> # v1
Signed-off-by: Tvrtko Ursulin <[email protected]>
---
  drivers/gpu/drm/i915/gem/i915_gem_clflush.c   |   9 +-
  drivers/gpu/drm/i915/gem/i915_gem_clflush.h   |   2 -
  drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c    |   4 +-
  drivers/gpu/drm/i915/gem/i915_gem_domain.c    | 163 +++++-------------
  .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |   4 +-
  drivers/gpu/drm/i915/gem/i915_gem_object.h    |  12 +-
  .../gpu/drm/i915/gem/i915_gem_object_types.h  |   6 +
  .../gpu/drm/i915/gem/selftests/huge_pages.c   |   8 -
  .../i915/gem/selftests/i915_gem_coherency.c   |  31 +++-
  .../drm/i915/gem/selftests/i915_gem_phys.c    |   8 +-
  .../drm/i915/gem/selftests/igt_gem_utils.c    |   3 +
  drivers/gpu/drm/i915/i915_gem.c               |   4 +-
  12 files changed, 89 insertions(+), 165 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c 
b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
index daf9284ef1f5..e4c24558eaa8 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_clflush.c
@@ -51,8 +51,6 @@ static struct clflush *clflush_work_create(struct 
drm_i915_gem_object *obj)
  {
        struct clflush *clflush;
- GEM_BUG_ON(!obj->cache_dirty);
-
        clflush = kmalloc(sizeof(*clflush), GFP_KERNEL);
        if (!clflush)
                return NULL;
@@ -101,13 +99,10 @@ bool i915_gem_clflush_object(struct drm_i915_gem_object 
*obj,
trace_i915_gem_object_clflush(obj); - clflush = NULL;
-       if (!(flags & I915_CLFLUSH_SYNC))
-               clflush = clflush_work_create(obj);
+       clflush = clflush_work_create(obj);
        if (clflush) {
                i915_sw_fence_await_reservation(&clflush->base.chain,
-                                               obj->base.resv, NULL, true,
-                                               
i915_fence_timeout(to_i915(obj->base.dev)),
+                                               obj->base.resv, NULL, true, 0,
                                                I915_FENCE_GFP);
                dma_resv_add_excl_fence(obj->base.resv, &clflush->base.dma);
                dma_fence_work_commit(&clflush->base);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_clflush.h 
b/drivers/gpu/drm/i915/gem/i915_gem_clflush.h
index e6c382973129..4cd5787d1507 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_clflush.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_clflush.h
@@ -9,12 +9,10 @@
#include <linux/types.h> -struct drm_i915_private;
  struct drm_i915_gem_object;
bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
                             unsigned int flags);
  #define I915_CLFLUSH_FORCE BIT(0)
-#define I915_CLFLUSH_SYNC BIT(1)
#endif /* __I915_GEM_CLFLUSH_H__ */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c 
b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index ccede73c6465..0926e0895ee6 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -132,7 +132,7 @@ static int i915_gem_begin_cpu_access(struct dma_buf 
*dma_buf, enum dma_data_dire
        if (!err)
                err = i915_gem_object_pin_pages(obj);
        if (!err) {
-               err = i915_gem_object_set_to_cpu_domain(obj, write);
+               i915_gem_object_set_to_cpu_domain(obj, write);
                i915_gem_object_unpin_pages(obj);
        }
        if (err == -EDEADLK) {
@@ -156,7 +156,7 @@ static int i915_gem_end_cpu_access(struct dma_buf *dma_buf, 
enum dma_data_direct
        if (!err)
                err = i915_gem_object_pin_pages(obj);
        if (!err) {
-               err = i915_gem_object_set_to_gtt_domain(obj, false);
+               i915_gem_object_set_to_gtt_domain(obj, false);
                i915_gem_object_unpin_pages(obj);
        }
        if (err == -EDEADLK) {
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c 
b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index 073822100da7..39fda97c49a7 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -49,7 +49,7 @@ flush_write_domain(struct drm_i915_gem_object *obj, unsigned 
int flush_domains)
                break;
case I915_GEM_DOMAIN_CPU:
-               i915_gem_clflush_object(obj, I915_CLFLUSH_SYNC);
+               i915_gem_clflush_object(obj, 0);
                break;
case I915_GEM_DOMAIN_RENDER:
@@ -97,34 +97,13 @@ void i915_gem_object_flush_if_display_locked(struct 
drm_i915_gem_object *obj)
   * This function returns when the move is complete, including waiting on
   * flushes to occur.
   */
-int
+void
  i915_gem_object_set_to_wc_domain(struct drm_i915_gem_object *obj, bool write)
  {
-       int ret;
-
        assert_object_held(obj);
- ret = i915_gem_object_wait(obj,
-                                  I915_WAIT_INTERRUPTIBLE |
-                                  (write ? I915_WAIT_ALL : 0),
-                                  MAX_SCHEDULE_TIMEOUT);
-       if (ret)
-               return ret;
-
        if (obj->write_domain == I915_GEM_DOMAIN_WC)
-               return 0;
-
-       /* Flush and acquire obj->pages so that we are coherent through
-        * direct access in memory with previous cached writes through
-        * shmemfs and that our cache domain tracking remains valid.
-        * For example, if the obj->filp was moved to swap without us
-        * being notified and releasing the pages, we would mistakenly
-        * continue to assume that the obj remained out of the CPU cached
-        * domain.
-        */
-       ret = i915_gem_object_pin_pages(obj);
-       if (ret)
-               return ret;
+               return;
flush_write_domain(obj, ~I915_GEM_DOMAIN_WC); @@ -145,9 +124,6 @@ i915_gem_object_set_to_wc_domain(struct drm_i915_gem_object *obj, bool write)
                obj->write_domain = I915_GEM_DOMAIN_WC;
                obj->mm.dirty = true;
        }
-
-       i915_gem_object_unpin_pages(obj);
-       return 0;
  }
/**
@@ -158,34 +134,13 @@ i915_gem_object_set_to_wc_domain(struct 
drm_i915_gem_object *obj, bool write)
   * This function returns when the move is complete, including waiting on
   * flushes to occur.
   */
-int
+void
  i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
  {
-       int ret;
-
        assert_object_held(obj);
- ret = i915_gem_object_wait(obj,
-                                  I915_WAIT_INTERRUPTIBLE |
-                                  (write ? I915_WAIT_ALL : 0),
-                                  MAX_SCHEDULE_TIMEOUT);
-       if (ret)
-               return ret;
-
        if (obj->write_domain == I915_GEM_DOMAIN_GTT)
-               return 0;
-
-       /* Flush and acquire obj->pages so that we are coherent through
-        * direct access in memory with previous cached writes through
-        * shmemfs and that our cache domain tracking remains valid.
-        * For example, if the obj->filp was moved to swap without us
-        * being notified and releasing the pages, we would mistakenly
-        * continue to assume that the obj remained out of the CPU cached
-        * domain.
-        */
-       ret = i915_gem_object_pin_pages(obj);
-       if (ret)
-               return ret;
+               return;
flush_write_domain(obj, ~I915_GEM_DOMAIN_GTT); @@ -214,9 +169,6 @@ i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
                                i915_vma_set_ggtt_write(vma);
                spin_unlock(&obj->vma.lock);
        }
-
-       i915_gem_object_unpin_pages(obj);
-       return 0;
  }
/**
@@ -431,25 +383,23 @@ i915_gem_object_pin_to_display_plane(struct 
drm_i915_gem_object *obj,
   * This function returns when the move is complete, including waiting on
   * flushes to occur.
   */
-int
+void
  i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
  {
-       int ret;
-
        assert_object_held(obj);
- ret = i915_gem_object_wait(obj,
-                                  I915_WAIT_INTERRUPTIBLE |
-                                  (write ? I915_WAIT_ALL : 0),
-                                  MAX_SCHEDULE_TIMEOUT);
-       if (ret)
-               return ret;
-
        flush_write_domain(obj, ~I915_GEM_DOMAIN_CPU);
/* Flush the CPU cache if it's still invalid. */
        if ((obj->read_domains & I915_GEM_DOMAIN_CPU) == 0) {
-               i915_gem_clflush_object(obj, I915_CLFLUSH_SYNC);
+               /*
+                * While we track when we write though the CPU cache
+                * (with obj->cache_dirty), this is only a guide as we do
+                * not know when the CPU may have speculatively populated
+                * the cache. We have to invalidate such speculative cachelines
+                * prior to reading writes by the GPU.
+                */
+               i915_gem_clflush_object(obj, 0);
                obj->read_domains |= I915_GEM_DOMAIN_CPU;
        }
@@ -463,8 +413,6 @@ i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
         */
        if (write)
                __start_cpu_write(obj);
-
-       return 0;
  }
/**
@@ -502,32 +450,14 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void 
*data,
        if (!obj)
                return -ENOENT;
- /*
-        * Try to flush the object off the GPU without holding the lock.
-        * We will repeat the flush holding the lock in the normal manner
-        * to catch cases where we are gazumped.
-        */
-       err = i915_gem_object_wait(obj,
-                                  I915_WAIT_INTERRUPTIBLE |
-                                  I915_WAIT_PRIORITY |
-                                  (write_domain ? I915_WAIT_ALL : 0),
-                                  MAX_SCHEDULE_TIMEOUT);
-       if (err)
-               goto out;
-
        if (i915_gem_object_is_userptr(obj)) {
                /*
                 * Try to grab userptr pages, iris uses set_domain to check
                 * userptr validity
                 */
                err = i915_gem_object_userptr_validate(obj);
-               if (!err)
-                       err = i915_gem_object_wait(obj,
-                                                  I915_WAIT_INTERRUPTIBLE |
-                                                  I915_WAIT_PRIORITY |
-                                                  (write_domain ? 
I915_WAIT_ALL : 0),
-                                                  MAX_SCHEDULE_TIMEOUT);
-               goto out;
+               if (err)
+                       goto out;
        }
/*
@@ -572,11 +502,11 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void 
*data,
                goto out_unpin;
if (read_domains & I915_GEM_DOMAIN_WC)
-               err = i915_gem_object_set_to_wc_domain(obj, write_domain);
+               i915_gem_object_set_to_wc_domain(obj, write_domain);
        else if (read_domains & I915_GEM_DOMAIN_GTT)
-               err = i915_gem_object_set_to_gtt_domain(obj, write_domain);
+               i915_gem_object_set_to_gtt_domain(obj, write_domain);
        else
-               err = i915_gem_object_set_to_cpu_domain(obj, write_domain);
+               i915_gem_object_set_to_cpu_domain(obj, write_domain);
out_unpin:
        i915_gem_object_unpin_pages(obj);
@@ -584,6 +514,11 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void 
*data,
  out_unlock:
        i915_gem_object_unlock(obj);
+ err = i915_gem_object_wait(obj,
+                                  I915_WAIT_INTERRUPTIBLE |
+                                  I915_WAIT_PRIORITY |
+                                  (write_domain ? I915_WAIT_ALL : 0),
+                                  MAX_SCHEDULE_TIMEOUT);
        if (!err && write_domain)
                i915_gem_object_invalidate_frontbuffer(obj, ORIGIN_CPU);
@@ -608,26 +543,21 @@ int i915_gem_object_prepare_read(struct drm_i915_gem_object *obj, assert_object_held(obj); - ret = i915_gem_object_wait(obj,
-                                  I915_WAIT_INTERRUPTIBLE,
-                                  MAX_SCHEDULE_TIMEOUT);
-       if (ret)
-               return ret;
-
        ret = i915_gem_object_pin_pages(obj);
        if (ret)
                return ret;
if (obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ ||
-           !static_cpu_has(X86_FEATURE_CLFLUSH)) {
-               ret = i915_gem_object_set_to_cpu_domain(obj, false);
-               if (ret)
-                       goto err_unpin;
-               else
-                       goto out;
-       }
+           !static_cpu_has(X86_FEATURE_CLFLUSH))
+               i915_gem_object_set_to_cpu_domain(obj, false);
+       else
+               flush_write_domain(obj, ~I915_GEM_DOMAIN_CPU);
- flush_write_domain(obj, ~I915_GEM_DOMAIN_CPU);
+       ret = i915_gem_object_wait(obj,
+                                  I915_WAIT_INTERRUPTIBLE,
+                                  MAX_SCHEDULE_TIMEOUT);
+       if (ret)
+               goto err_unpin;
/* If we're not in the cpu read domain, set ourself into the gtt
         * read domain and manually flush cachelines (if required). This
@@ -638,7 +568,6 @@ int i915_gem_object_prepare_read(struct drm_i915_gem_object 
*obj,
            !(obj->read_domains & I915_GEM_DOMAIN_CPU))
                *needs_clflush = CLFLUSH_BEFORE;
-out:
        /* return with the pages pinned */
        return 0;
@@ -658,27 +587,22 @@ int i915_gem_object_prepare_write(struct drm_i915_gem_object *obj, assert_object_held(obj); - ret = i915_gem_object_wait(obj,
-                                  I915_WAIT_INTERRUPTIBLE |
-                                  I915_WAIT_ALL,
-                                  MAX_SCHEDULE_TIMEOUT);
-       if (ret)
-               return ret;
-
        ret = i915_gem_object_pin_pages(obj);
        if (ret)
                return ret;
if (obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_WRITE ||
-           !static_cpu_has(X86_FEATURE_CLFLUSH)) {
-               ret = i915_gem_object_set_to_cpu_domain(obj, true);
-               if (ret)
-                       goto err_unpin;
-               else
-                       goto out;
-       }
+           !static_cpu_has(X86_FEATURE_CLFLUSH))
+               i915_gem_object_set_to_cpu_domain(obj, true);
+       else
+               flush_write_domain(obj, ~I915_GEM_DOMAIN_CPU);
- flush_write_domain(obj, ~I915_GEM_DOMAIN_CPU);
+       ret = i915_gem_object_wait(obj,
+                                  I915_WAIT_INTERRUPTIBLE |
+                                  I915_WAIT_ALL,
+                                  MAX_SCHEDULE_TIMEOUT);
+       if (ret)
+               goto err_unpin;
/* If we're not in the cpu write domain, set ourself into the
         * gtt write domain and manually flush cachelines (as required).
@@ -696,7 +620,6 @@ int i915_gem_object_prepare_write(struct 
drm_i915_gem_object *obj,
                        *needs_clflush |= CLFLUSH_BEFORE;
        }
-out:
        i915_gem_object_invalidate_frontbuffer(obj, ORIGIN_CPU);
        obj->mm.dirty = true;
        /* return with the pages pinned */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c 
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 297143511f99..40fda9e81a78 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1212,9 +1212,7 @@ static void *reloc_iomap(struct drm_i915_gem_object *obj,
                if (use_cpu_reloc(cache, obj))
                        return NULL;
- err = i915_gem_object_set_to_gtt_domain(obj, true);
-               if (err)
-                       return ERR_PTR(err);
+               i915_gem_object_set_to_gtt_domain(obj, true);
vma = i915_gem_object_ggtt_pin_ww(obj, &eb->ww, NULL, 0, 0,
                                                  PIN_MAPPABLE |
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h 
b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 2ebd79537aea..8bbc835e70ce 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -515,12 +515,12 @@ void i915_gem_object_set_cache_coherency(struct 
drm_i915_gem_object *obj,
  void i915_gem_object_flush_if_display(struct drm_i915_gem_object *obj);
  void i915_gem_object_flush_if_display_locked(struct drm_i915_gem_object *obj);
-int __must_check
-i915_gem_object_set_to_wc_domain(struct drm_i915_gem_object *obj, bool write);
-int __must_check
-i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write);
-int __must_check
-i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write);
+void i915_gem_object_set_to_wc_domain(struct drm_i915_gem_object *obj,
+                                     bool write);
+void i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj,
+                                      bool write);
+void i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj,
+                                      bool write);
  struct i915_vma * __must_check
  i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
                                     struct i915_gem_ww_ctx *ww,
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h 
b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 0727d0c76aa0..b8f0413bc3b0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -188,6 +188,12 @@ struct drm_i915_gem_object {
        unsigned int cache_coherent:2;
  #define I915_BO_CACHE_COHERENT_FOR_READ BIT(0)
  #define I915_BO_CACHE_COHERENT_FOR_WRITE BIT(1)
+       /*
+        * Note cache_dirty is only a guide; we know when we have written
+        * through the CPU cache, but we do not know when the CPU may have
+        * speculatively populated the cache. Before a read via the cache
+        * of GPU written memory, we have to cautiously invalidate the cache.
+        */
        unsigned int cache_dirty:1;
/**
diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c 
b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
index 33dd4e2a1010..d85ca79ac433 100644
--- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
@@ -972,14 +972,6 @@ static int gpu_write(struct intel_context *ce,
                     u32 dw,
                     u32 val)
  {
-       int err;
-
-       i915_gem_object_lock(vma->obj, NULL);
-       err = i915_gem_object_set_to_gtt_domain(vma->obj, true);
-       i915_gem_object_unlock(vma->obj);
-       if (err)
-               return err;
-
        return igt_gpu_fill_dw(ce, vma, dw * sizeof(u32),
                               vma->size >> PAGE_SHIFT, val);
  }
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c 
b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
index e937b6629019..77ba6d1ef4e4 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
@@ -90,8 +90,13 @@ static int gtt_set(struct context *ctx, unsigned long 
offset, u32 v)
        int err = 0;
i915_gem_object_lock(ctx->obj, NULL);
-       err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
+       i915_gem_object_set_to_gtt_domain(ctx->obj, true);
        i915_gem_object_unlock(ctx->obj);
+
+       err = i915_gem_object_wait(ctx->obj,
+                                  I915_WAIT_ALL |
+                                  I915_WAIT_INTERRUPTIBLE,
+                                  HZ / 2);
        if (err)
                return err;
@@ -123,8 +128,12 @@ static int gtt_get(struct context *ctx, unsigned long offset, u32 *v)
        int err = 0;
i915_gem_object_lock(ctx->obj, NULL);
-       err = i915_gem_object_set_to_gtt_domain(ctx->obj, false);
+       i915_gem_object_set_to_gtt_domain(ctx->obj, false);
        i915_gem_object_unlock(ctx->obj);
+
+       err = i915_gem_object_wait(ctx->obj,
+                                  I915_WAIT_INTERRUPTIBLE,
+                                  HZ / 2);
        if (err)
                return err;
@@ -155,8 +164,13 @@ static int wc_set(struct context *ctx, unsigned long offset, u32 v)
        int err;
i915_gem_object_lock(ctx->obj, NULL);
-       err = i915_gem_object_set_to_wc_domain(ctx->obj, true);
+       i915_gem_object_set_to_wc_domain(ctx->obj, true);
        i915_gem_object_unlock(ctx->obj);
+
+       err = i915_gem_object_wait(ctx->obj,
+                                  I915_WAIT_ALL |
+                                  I915_WAIT_INTERRUPTIBLE,
+                                  HZ / 2);
        if (err)
                return err;
@@ -178,8 +192,12 @@ static int wc_get(struct context *ctx, unsigned long offset, u32 *v)
        int err;
i915_gem_object_lock(ctx->obj, NULL);
-       err = i915_gem_object_set_to_wc_domain(ctx->obj, false);
+       i915_gem_object_set_to_wc_domain(ctx->obj, false);
        i915_gem_object_unlock(ctx->obj);
+
+       err = i915_gem_object_wait(ctx->obj,
+                                  I915_WAIT_INTERRUPTIBLE,
+                                  HZ / 2);
        if (err)
                return err;
@@ -205,9 +223,7 @@ static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
                return PTR_ERR(vma);
i915_gem_object_lock(ctx->obj, NULL);
-       err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
-       if (err)
-               goto out_unlock;
+       i915_gem_object_set_to_gtt_domain(ctx->obj, false);

IIRC Daniel pointed out that this looks odd, since this now becomes write=false for some reason. I think keep this as write=true, since it does look like that is what gpu_set wants.

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