[Intel-gfx] [RFC 2/7] drm/i915/gvt: Introduce GEN8 private PAT ops

[Zhi Wang]

This patch introduces private PAT operations for GEN8.

The "get_pat_value" operation offers an API to get a PPAT entry from the
virtual or physical PPAT MMIO registers. Similar with the "get_pat_value",
the "set_pat_value" operation offers the API to write a PPAT entry back to
PPAT MMIO registers. The caller doesn't need to care about the PPAT MMIO
layout, since the layout is different between different GENs.

The "match_pat_value" will try to compare two PAT entries and give a score
to indicate how perfect they match with each other. The most important
attribute is "cache attribute", which affects the correctness and has to
be matched. Other attributes gain different scores by the their
importance in a partial match.

Signed-off-by: Zhi Wang <zhi.a.wang at intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 81 ++++++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/gvt/gtt.h |  9 +++++
 2 files changed, 90 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index e6dfc33..16bfca9 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -402,6 +402,80 @@ DEFINE_PPGTT_GMA_TO_INDEX(gen8, l3_pdp, (gma >> 30 & 0x3));
 DEFINE_PPGTT_GMA_TO_INDEX(gen8, l4_pdp, (gma >> 30 & 0x1ff));
 DEFINE_PPGTT_GMA_TO_INDEX(gen8, pml4, (gma >> 39 & 0x1ff));
 
+static unsigned int gen8_pat_get_value(u32 *mem, unsigned int index,
+				       struct intel_gvt *gvt)
+{
+	struct drm_i915_private *dev_priv = gvt->dev_priv;
+	int reg_index = index / 4;
+	u32 buf[2];
+
+	if (WARN_ON(reg_index >= 2))
+		return 0;
+
+	if (!mem) {
+		mem = buf;
+		mem[reg_index] = reg_index ? I915_READ(GEN8_PRIVATE_PAT_HI) :
+				 I915_READ(GEN8_PRIVATE_PAT_LO);
+	}
+
+	index -= reg_index * 4;
+	return (mem[reg_index] >> (index * 8)) & 0x3f;
+}
+
+static void gen8_pat_set_value(u32 *mem, unsigned int index, unsigned int value,
+			       struct intel_gvt *gvt)
+{
+	struct drm_i915_private *dev_priv = gvt->dev_priv;
+	int reg_index = index / 4;
+	u32 buf[2];
+	bool writeback = false;
+
+	if (WARN_ON(reg_index >= 2))
+		return;
+
+	if (!mem) {
+		mem = buf;
+		writeback = true;
+		mem[reg_index] = reg_index ? I915_READ(GEN8_PRIVATE_PAT_HI) :
+				 I915_READ(GEN8_PRIVATE_PAT_LO);
+	}
+
+	index -= reg_index * 4;
+
+	mem[reg_index] &= ~(0xff << (index * 8));
+	mem[reg_index] |= ((value & 0x3f) << (index * 8));
+
+	if (writeback) {
+		if (reg_index)
+			I915_WRITE(GEN8_PRIVATE_PAT_LO, mem[1]);
+		else
+			I915_WRITE(GEN8_PRIVATE_PAT_LO, mem[0]);
+	}
+}
+
+#define gen8_pat_ca(v) ((v) & 0x3)
+#define gen8_pat_tc(v) ((v) >> 2 & 0x3)
+#define gen8_pat_age(v) ((v) >> 4 & 0x3)
+
+static unsigned int gen8_pat_match_value(unsigned int src, unsigned int dst)
+{
+	unsigned int score = 0;
+
+	if (gen8_pat_ca(src) != gen8_pat_ca(dst))
+		return 0;
+
+	if (gen8_pat_age(src) == gen8_pat_age(dst))
+		score += 1;
+
+	if (gen8_pat_tc(src) == gen8_pat_tc(dst))
+		score += 2;
+
+	if (score == 3)
+		return ~0;
+
+	return score;
+}
+
 static struct intel_gvt_gtt_pte_ops gen8_gtt_pte_ops = {
 	.get_entry = gtt_get_entry64,
 	.set_entry = gtt_set_entry64,
@@ -421,6 +495,12 @@ static struct intel_gvt_gtt_gma_ops gen8_gtt_gma_ops = {
 	.gma_to_pml4_index = gen8_gma_to_pml4_index,
 };
 
+static struct intel_gvt_gtt_pat_ops gen8_pat_ops = {
+	.get_pat_value = gen8_pat_get_value,
+	.set_pat_value = gen8_pat_set_value,
+	.match_pat_value = gen8_pat_match_value,
+};
+
 static int gtt_entry_p2m(struct intel_vgpu *vgpu, struct intel_gvt_gtt_entry *p,
 		struct intel_gvt_gtt_entry *m)
 {
@@ -2267,6 +2347,7 @@ int intel_gvt_init_gtt(struct intel_gvt *gvt)
 		|| IS_KABYLAKE(gvt->dev_priv)) {
 		gvt->gtt.pte_ops = &gen8_gtt_pte_ops;
 		gvt->gtt.gma_ops = &gen8_gtt_gma_ops;
+		gvt->gtt.pat_ops = &gen8_pat_ops;
 		gvt->gtt.mm_alloc_page_table = gen8_mm_alloc_page_table;
 		gvt->gtt.mm_free_page_table = gen8_mm_free_page_table;
 	} else {
diff --git a/drivers/gpu/drm/i915/gvt/gtt.h b/drivers/gpu/drm/i915/gvt/gtt.h
index 30a4c8d..7a9eb05 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.h
+++ b/drivers/gpu/drm/i915/gvt/gtt.h
@@ -77,9 +77,18 @@ struct intel_gvt_gtt_gma_ops {
 	unsigned long (*gma_to_pml4_index)(unsigned long gma);
 };
 
+struct intel_gvt_gtt_pat_ops {
+	unsigned int (*get_pat_value)(u32 *mem, unsigned int index,
+				      struct intel_gvt *gvt);
+	void (*set_pat_value)(u32 *mem, unsigned int index, unsigned int value,
+			      struct intel_gvt *gvt);
+	unsigned int (*match_pat_value)(unsigned int src, unsigned int dst);
+};
+
 struct intel_gvt_gtt {
 	struct intel_gvt_gtt_pte_ops *pte_ops;
 	struct intel_gvt_gtt_gma_ops *gma_ops;
+	struct intel_gvt_gtt_pat_ops *pat_ops;
 	int (*mm_alloc_page_table)(struct intel_vgpu_mm *mm);
 	void (*mm_free_page_table)(struct intel_vgpu_mm *mm);
 	struct list_head oos_page_use_list_head;
-- 
2.7.4