[Intel-gfx] [PATCH] drm/i915/gem: Implement legacy MI_STORE_DATA_IMM

[Chris Wilson]

The older arches did not convert MI_STORE_DATA_IMM to using the GTT, but
left them writing to a physical address. The notes suggest that the
primary reason would be so that the writes were cache coherent, as the
CPU cache uses physical tagging. As such we did not implement the
legacy variant of MI_STORE_DATA_IMM and so left all the relocations
synchronous -- but with a small function to convert from the vma address
into the physical address, we can implement asynchronous relocs on these
older arches, fixing up a few tests that require them.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/757
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 35 +++++++++++++++++--
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index cce7df231cb9..8ffdab80d882 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1376,6 +1376,11 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
 	return err;
 }
 
+static bool can_store_dword(const struct intel_engine_cs *engine)
+{
+	return engine->class != VIDEO_DECODE_CLASS || !IS_GEN(engine->i915, 6);
+}
+
 static u32 *reloc_gpu(struct i915_execbuffer *eb,
 		      struct i915_vma *vma,
 		      unsigned int len)
@@ -1387,9 +1392,9 @@ static u32 *reloc_gpu(struct i915_execbuffer *eb,
 	if (unlikely(!cache->rq)) {
 		struct intel_engine_cs *engine = eb->engine;
 
-		if (!intel_engine_can_store_dword(engine)) {
+		if (!can_store_dword(engine)) {
 			engine = engine->gt->engine_class[COPY_ENGINE_CLASS][0];
-			if (!engine || !intel_engine_can_store_dword(engine))
+			if (!engine)
 				return ERR_PTR(-ENODEV);
 		}
 
@@ -1435,6 +1440,20 @@ static inline bool use_reloc_gpu(struct i915_vma *vma)
 	return !dma_resv_test_signaled_rcu(vma->resv, true);
 }
 
+static unsigned long vma_phys_addr(struct i915_vma *vma, u32 offset)
+{
+	struct page *page;
+	unsigned long addr;
+
+	GEM_BUG_ON(vma->pages != vma->obj->mm.pages);
+
+	page = i915_gem_object_get_page(vma->obj, offset >> PAGE_SHIFT);
+	addr = PFN_PHYS(page_to_pfn(page));
+	GEM_BUG_ON(overflows_type(addr, u32)); /* expected dma32 */
+
+	return addr + offset_in_page(offset);
+}
+
 static u64
 relocate_entry(struct i915_vma *vma,
 	       const struct drm_i915_gem_relocation_entry *reloc,
@@ -1489,15 +1508,25 @@ relocate_entry(struct i915_vma *vma,
 			*batch++ = 0;
 			*batch++ = addr;
 			*batch++ = target_offset;
+		} else if (IS_I965G(eb->i915)) {
+			*batch++ = MI_STORE_DWORD_IMM_GEN4;
+			*batch++ = 0;
+			*batch++ = vma_phys_addr(vma, offset);
+			*batch++ = target_offset;
 		} else if (gen >= 4) {
 			*batch++ = MI_STORE_DWORD_IMM_GEN4 | MI_USE_GGTT;
 			*batch++ = 0;
 			*batch++ = addr;
 			*batch++ = target_offset;
-		} else {
+		} else if (gen >= 3 &&
+			   !(IS_I915G(eb->i915) || IS_I915GM(eb->i915))) {
 			*batch++ = MI_STORE_DWORD_IMM | MI_MEM_VIRTUAL;
 			*batch++ = addr;
 			*batch++ = target_offset;
+		} else {
+			*batch++ = MI_STORE_DWORD_IMM;
+			*batch++ = vma_phys_addr(vma, offset);
+			*batch++ = target_offset;
 		}
 
 		goto out;
-- 
2.20.1