drm/i915/gvt: support inconsecutive partial gtt entry write

Previously we assumed two 4-byte writes to the same PTE coming in sequence.
But recently we observed inconsecutive partial write happening as well. So
this patch enhances the previous solution. It now uses a list to save more
partial writes. If one partial write can be combined with another one in
the list to construct a full PTE, update its shadow entry. Otherwise, save
the partial write in the list.

v2: invalidate old entry and flush ggtt (Zhenyu)
v3: split old ggtt page unmap to another patch (Zhenyu)
v4: refine codes (Zhenyu)

Signed-off-by: Hang Yuan <hang.yuan@linux.intel.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Cc: Xiaolin Zhang <xiaolin.zhang@intel.com>
Cc: Zhenyu Wang <zhenyu.z.wang@intel.com>
Reviewed-by: Xiaolin Zhang <xiaolin.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index c11e353ca9043350c007329d99d8a48c2441324e..919de5a1bafb75c3a2a318bf8c3b135ddc23367f 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1901,7 +1901,6 @@ static struct intel_vgpu_mm *intel_vgpu_create_ggtt_mm(struct intel_vgpu *vgpu)
                vgpu_free_mm(mm);
                return ERR_PTR(-ENOMEM);
        }
-       mm->ggtt_mm.last_partial_off = -1UL;
 
        return mm;
 }
@@ -1926,7 +1925,6 @@ void _intel_vgpu_mm_release(struct kref *mm_ref)
                invalidate_ppgtt_mm(mm);
        } else {
                vfree(mm->ggtt_mm.virtual_ggtt);
-               mm->ggtt_mm.last_partial_off = -1UL;
        }
 
        vgpu_free_mm(mm);
@@ -2164,6 +2162,8 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
        struct intel_gvt_gtt_entry e, m;
        dma_addr_t dma_addr;
        int ret;
+       struct intel_gvt_partial_pte *partial_pte, *pos, *n;
+       bool partial_update = false;
 
        if (bytes != 4 && bytes != 8)
                return -EINVAL;
@@ -2174,68 +2174,57 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
        if (!vgpu_gmadr_is_valid(vgpu, gma))
                return 0;
 
-       ggtt_get_guest_entry(ggtt_mm, &e, g_gtt_index);
-
+       e.type = GTT_TYPE_GGTT_PTE;
        memcpy((void *)&e.val64 + (off & (info->gtt_entry_size - 1)), p_data,
                        bytes);
 
        /* If ggtt entry size is 8 bytes, and it's split into two 4 bytes
-        * write, we assume the two 4 bytes writes are consecutive.
-        * Otherwise, we abort and report error
+        * write, save the first 4 bytes in a list and update virtual
+        * PTE. Only update shadow PTE when the second 4 bytes comes.
         */
        if (bytes < info->gtt_entry_size) {
-               if (ggtt_mm->ggtt_mm.last_partial_off == -1UL) {
-                       /* the first partial part*/
-                       ggtt_mm->ggtt_mm.last_partial_off = off;
-                       ggtt_mm->ggtt_mm.last_partial_data = e.val64;
-                       return 0;
-               } else if ((g_gtt_index ==
-                               (ggtt_mm->ggtt_mm.last_partial_off >>
-                               info->gtt_entry_size_shift)) &&
-                       (off != ggtt_mm->ggtt_mm.last_partial_off)) {
-                       /* the second partial part */
-
-                       int last_off = ggtt_mm->ggtt_mm.last_partial_off &
-                               (info->gtt_entry_size - 1);
-
-                       memcpy((void *)&e.val64 + last_off,
-                               (void *)&ggtt_mm->ggtt_mm.last_partial_data +
-                               last_off, bytes);
-
-                       ggtt_mm->ggtt_mm.last_partial_off = -1UL;
-               } else {
-                       int last_offset;
-
-                       gvt_vgpu_err("failed to populate guest ggtt entry: abnormal ggtt entry write sequence, last_partial_off=%lx, offset=%x, bytes=%d, ggtt entry size=%d\n",
-                                       ggtt_mm->ggtt_mm.last_partial_off, off,
-                                       bytes, info->gtt_entry_size);
-
-                       /* set host ggtt entry to scratch page and clear
-                        * virtual ggtt entry as not present for last
-                        * partially write offset
-                        */
-                       last_offset = ggtt_mm->ggtt_mm.last_partial_off &
-                                       (~(info->gtt_entry_size - 1));
-
-                       ggtt_get_host_entry(ggtt_mm, &m, last_offset);
-                       ggtt_invalidate_pte(vgpu, &m);
-                       ops->set_pfn(&m, gvt->gtt.scratch_mfn);
-                       ops->clear_present(&m);
-                       ggtt_set_host_entry(ggtt_mm, &m, last_offset);
-                       ggtt_invalidate(gvt->dev_priv);
-
-                       ggtt_get_guest_entry(ggtt_mm, &e, last_offset);
-                       ops->clear_present(&e);
-                       ggtt_set_guest_entry(ggtt_mm, &e, last_offset);
-
-                       ggtt_mm->ggtt_mm.last_partial_off = off;
-                       ggtt_mm->ggtt_mm.last_partial_data = e.val64;
+               bool found = false;
+
+               list_for_each_entry_safe(pos, n,
+                               &ggtt_mm->ggtt_mm.partial_pte_list, list) {
+                       if (g_gtt_index == pos->offset >>
+                                       info->gtt_entry_size_shift) {
+                               if (off != pos->offset) {
+                                       /* the second partial part*/
+                                       int last_off = pos->offset &
+                                               (info->gtt_entry_size - 1);
+
+                                       memcpy((void *)&e.val64 + last_off,
+                                               (void *)&pos->data + last_off,
+                                               bytes);
+
+                                       list_del(&pos->list);
+                                       kfree(pos);
+                                       found = true;
+                                       break;
+                               }
+
+                               /* update of the first partial part */
+                               pos->data = e.val64;
+                               ggtt_set_guest_entry(ggtt_mm, &e, g_gtt_index);
+                               return 0;
+                       }
+               }
 
-                       return 0;
+               if (!found) {
+                       /* the first partial part */
+                       partial_pte = kzalloc(sizeof(*partial_pte), GFP_KERNEL);
+                       if (!partial_pte)
+                               return -ENOMEM;
+                       partial_pte->offset = off;
+                       partial_pte->data = e.val64;
+                       list_add_tail(&partial_pte->list,
+                               &ggtt_mm->ggtt_mm.partial_pte_list);
+                       partial_update = true;
                }
        }
 
-       if (ops->test_present(&e)) {
+       if (!partial_update && (ops->test_present(&e))) {
                gfn = ops->get_pfn(&e);
                m = e;
 
@@ -2428,6 +2417,8 @@ int intel_vgpu_init_gtt(struct intel_vgpu *vgpu)
 
        intel_vgpu_reset_ggtt(vgpu, false);
 
+       INIT_LIST_HEAD(&gtt->ggtt_mm->ggtt_mm.partial_pte_list);
+
        return create_scratch_page_tree(vgpu);
 }
 
@@ -2452,6 +2443,14 @@ static void intel_vgpu_destroy_all_ppgtt_mm(struct intel_vgpu *vgpu)
 
 static void intel_vgpu_destroy_ggtt_mm(struct intel_vgpu *vgpu)
 {
+       struct intel_gvt_partial_pte *pos;
+
+       list_for_each_entry(pos,
+                       &vgpu->gtt.ggtt_mm->ggtt_mm.partial_pte_list, list) {
+               gvt_dbg_mm("partial PTE update on hold 0x%lx : 0x%llx\n",
+                       pos->offset, pos->data);
+               kfree(pos);
+       }
        intel_vgpu_destroy_mm(vgpu->gtt.ggtt_mm);
        vgpu->gtt.ggtt_mm = NULL;
 }

diff --git a/drivers/gpu/drm/i915/gvt/gtt.h b/drivers/gpu/drm/i915/gvt/gtt.h
index 7a9b36176efb7fca7198527512f8873ad21248cb..a11bfee1e0c85b84190d5321f064193ff6977468 100644 (file)
--- a/drivers/gpu/drm/i915/gvt/gtt.h
+++ b/drivers/gpu/drm/i915/gvt/gtt.h
@@ -133,6 +133,12 @@ enum intel_gvt_mm_type {
 
 #define GVT_RING_CTX_NR_PDPS   GEN8_3LVL_PDPES
 
+struct intel_gvt_partial_pte {
+       unsigned long offset;
+       u64 data;
+       struct list_head list;
+};
+
 struct intel_vgpu_mm {
        enum intel_gvt_mm_type type;
        struct intel_vgpu *vgpu;
@@ -157,8 +163,7 @@ struct intel_vgpu_mm {
                } ppgtt_mm;
                struct {
                        void *virtual_ggtt;
-                       unsigned long last_partial_off;
-                       u64 last_partial_data;
+                       struct list_head partial_pte_list;
                } ggtt_mm;
        };
 };