2 files changed, 60 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index 23296547da95..4efec8fa6c1d 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -1592,6 +1592,7 @@ 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;
 }
@@ -1616,6 +1617,7 @@ 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);
@@ -1868,6 +1870,62 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
         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
+         */
+        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;
+
+                        return 0;
+                }
+        }
+
         if (ops->test_present(&e)) {
                 gfn = ops->get_pfn(&e);
                 m = e;
diff --git a/drivers/gpu/drm/i915/gvt/gtt.h b/drivers/gpu/drm/i915/gvt/gtt.h
index 3792f2b7f4ff..97e62647418a 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.h
+++ b/drivers/gpu/drm/i915/gvt/gtt.h
@@ -150,6 +150,8 @@ struct intel_vgpu_mm {
                 } ppgtt_mm;
                 struct {
                         void *virtual_ggtt;
+                        unsigned long last_partial_off;
+                        u64 last_partial_data;
                 } ggtt_mm;
         };
 };