[PATCH v3 1/2] drm/i915/gvt: Missed to cancel dma map for ggtt entries

[changbin.du at intel.com]

From: Changbin Du <changbin.du at intel.com>

We have canceled dma map for ppgtt entries. Also we need to do it for
ggtt entries when them are invalidated.

This can fix task hung issue as:
[13517.791767] INFO: task gvt_service_thr:1081 blocked for more than 120 seconds.
[13517.792584] Not tainted 4.14.15+ #3
[13517.793417] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[13517.794267] gvt_service_thr D 0 1081 2 0x80000000
[13517.795132] Call Trace:
[13517.795996] ? __schedule+0x493/0x77b
[13517.796859] schedule+0x79/0x82
[13517.797740] schedule_preempt_disabled+0x5/0x6
[13517.798614] __mutex_lock.isra.0+0x2b5/0x445
[13517.799504] ? __switch_to_asm+0x24/0x60
[13517.800381] ? intel_gvt_cleanup+0x10/0x10
[13517.801261] ? intel_gvt_schedule+0x19/0x2b9
[13517.802107] intel_gvt_schedule+0x19/0x2b9
[13517.802954] ? intel_gvt_cleanup+0x10/0x10
[13517.803824] gvt_service_thread+0xe3/0x10d
[13517.804704] ? wait_woken+0x68/0x68
[13517.805588] kthread+0x118/0x120
[13517.806478] ? kthread_create_on_node+0x3a/0x3a
[13517.807381] ? call_usermodehelper_exec_async+0x113/0x11a
[13517.808307] ret_from_fork+0x35/0x40

v3: split out ggtt reset case.
v2: also unmap ggtt during reset.

Signed-off-by: Changbin Du <changbin.du at intel.com>
---
 drivers/gpu/drm/i915/gvt/gtt.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/gtt.c b/drivers/gpu/drm/i915/gvt/gtt.c
index d292812..8c9477c 100644
--- a/drivers/gpu/drm/i915/gvt/gtt.c
+++ b/drivers/gpu/drm/i915/gvt/gtt.c
@@ -530,6 +530,16 @@ static void ggtt_set_guest_entry(struct intel_vgpu_mm *mm,
 			   false, 0, mm->vgpu);
 }
 
+static void ggtt_get_host_entry(struct intel_vgpu_mm *mm,
+		struct intel_gvt_gtt_entry *entry, unsigned long index)
+{
+	struct intel_gvt_gtt_pte_ops *pte_ops = mm->vgpu->gvt->gtt.pte_ops;
+
+	GEM_BUG_ON(mm->type != INTEL_GVT_MM_GGTT);
+
+	pte_ops->get_entry(NULL, entry, index, false, 0, mm->vgpu);
+}
+
 static void ggtt_set_host_entry(struct intel_vgpu_mm *mm,
 		struct intel_gvt_gtt_entry *entry, unsigned long index)
 {
@@ -1818,6 +1828,18 @@ int intel_vgpu_emulate_ggtt_mmio_read(struct intel_vgpu *vgpu, unsigned int off,
 	return ret;
 }
 
+static void ggtt_invalidate_pte(struct intel_vgpu *vgpu,
+		struct intel_gvt_gtt_entry *entry)
+{
+	struct intel_gvt_gtt_pte_ops *pte_ops = vgpu->gvt->gtt.pte_ops;
+	unsigned long pfn;
+
+	pfn = pte_ops->get_pfn(entry);
+	if (pfn != vgpu->gvt->gtt.scratch_mfn)
+		intel_gvt_hypervisor_dma_unmap_guest_page(vgpu,
+						pfn << PAGE_SHIFT);
+}
+
 static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 	void *p_data, unsigned int bytes)
 {
@@ -1844,10 +1866,10 @@ 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);
-	m = e;
 
 	if (ops->test_present(&e)) {
 		gfn = ops->get_pfn(&e);
+		m = e;
 
 		/* one PTE update may be issued in multiple writes and the
 		 * first write may not construct a valid gfn
@@ -1868,8 +1890,12 @@ static int emulate_ggtt_mmio_write(struct intel_vgpu *vgpu, unsigned int off,
 			ops->set_pfn(&m, gvt->gtt.scratch_mfn);
 		} else
 			ops->set_pfn(&m, dma_addr >> PAGE_SHIFT);
-	} else
+	} else {
+		ggtt_get_host_entry(ggtt_mm, &m, g_gtt_index);
+		ggtt_invalidate_pte(vgpu, &m);
 		ops->set_pfn(&m, gvt->gtt.scratch_mfn);
+		ops->clear_present(&m);
+	}
 
 out:
 	ggtt_set_host_entry(ggtt_mm, &m, g_gtt_index);
-- 
2.7.4