drm/nouveau: protect channel create/destroy and irq handler with a spinlock

The nv50 pgraph handler (for example) could reenable pgraph fifo access
and that would be bad when pgraph context is being unloaded (we need the
guarantee a ctxprog isn't running).

Signed-off-by: Maarten Maathuis <madman2003@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

7 files changed, 36 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_channel.c b/drivers/gpu/drm/nouveau/nouveau_channel.c
index 2281f99da7fc..f7ca95003f54 100644
--- a/drivers/gpu/drm/nouveau/nouveau_channel.c
+++ b/drivers/gpu/drm/nouveau/nouveau_channel.c
@@ -275,9 +275,18 @@ nouveau_channel_free(struct nouveau_channel *chan)
          */
         nouveau_fence_fini(chan);
 
-        /* Ensure the channel is no longer active on the GPU */
+        /* This will prevent pfifo from switching channels. */
         pfifo->reassign(dev, false);
 
+        /* We want to give pgraph a chance to idle and get rid of all potential
+         * errors. We need to do this before the lock, otherwise the irq handler
+         * is unable to process them.
+         */
+        if (pgraph->channel(dev) == chan)
+                nouveau_wait_for_idle(dev);
+
+        spin_lock_irqsave(&dev_priv->context_switch_lock, flags);
+
         pgraph->fifo_access(dev, false);
         if (pgraph->channel(dev) == chan)
                 pgraph->unload_context(dev);
@@ -293,6 +302,8 @@ nouveau_channel_free(struct nouveau_channel *chan)
 
         pfifo->reassign(dev, true);
 
+        spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
+
         /* Release the channel's resources */
         nouveau_gpuobj_ref_del(dev, &chan->pushbuf);
         if (chan->pushbuf_bo) {
diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h b/drivers/gpu/drm/nouveau/nouveau_drv.h
index 1c15ef37b71c..52cc13bd02b9 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drv.h
+++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
@@ -533,6 +533,9 @@ struct drm_nouveau_private {
         struct nouveau_engine engine;
         struct nouveau_channel *channel;
 
+        /* For PFIFO and PGRAPH. */
+        spinlock_t context_switch_lock;
+
         /* RAMIN configuration, RAMFC, RAMHT and RAMRO offsets */
         struct nouveau_gpuobj *ramht;
         uint32_t ramin_rsvd_vram;
diff --git a/drivers/gpu/drm/nouveau/nouveau_irq.c b/drivers/gpu/drm/nouveau/nouveau_irq.c
index 447f9f69d6b1..95220ddebb45 100644
--- a/drivers/gpu/drm/nouveau/nouveau_irq.c
+++ b/drivers/gpu/drm/nouveau/nouveau_irq.c
@@ -691,11 +691,14 @@ nouveau_irq_handler(DRM_IRQ_ARGS)
         struct drm_device *dev = (struct drm_device *)arg;
         struct drm_nouveau_private *dev_priv = dev->dev_private;
         uint32_t status, fbdev_flags = 0;
+        unsigned long flags;
 
         status = nv_rd32(dev, NV03_PMC_INTR_0);
         if (!status)
                 return IRQ_NONE;
 
+        spin_lock_irqsave(&dev_priv->context_switch_lock, flags);
+
         if (dev_priv->fbdev_info) {
                 fbdev_flags = dev_priv->fbdev_info->flags;
                 dev_priv->fbdev_info->flags |= FBINFO_HWACCEL_DISABLED;
@@ -733,5 +736,7 @@ nouveau_irq_handler(DRM_IRQ_ARGS)
         if (dev_priv->fbdev_info)
                 dev_priv->fbdev_info->flags = fbdev_flags;
 
+        spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
+
         return IRQ_HANDLED;
 }
diff --git a/drivers/gpu/drm/nouveau/nouveau_state.c b/drivers/gpu/drm/nouveau/nouveau_state.c
index a4851af5b05e..ed5ac0b9a0ac 100644
--- a/drivers/gpu/drm/nouveau/nouveau_state.c
+++ b/drivers/gpu/drm/nouveau/nouveau_state.c
@@ -391,6 +391,7 @@ nouveau_card_init(struct drm_device *dev)
                 goto out;
         engine = &dev_priv->engine;
         dev_priv->init_state = NOUVEAU_CARD_INIT_FAILED;
+        spin_lock_init(&dev_priv->context_switch_lock);
 
         /* Parse BIOS tables / Run init tables if card not POSTed */
         if (drm_core_check_feature(dev, DRIVER_MODESET)) {
diff --git a/drivers/gpu/drm/nouveau/nv04_fifo.c b/drivers/gpu/drm/nouveau/nv04_fifo.c
index f31347b8c9b0..66fe55983b6e 100644
--- a/drivers/gpu/drm/nouveau/nv04_fifo.c
+++ b/drivers/gpu/drm/nouveau/nv04_fifo.c
@@ -117,6 +117,7 @@ nv04_fifo_create_context(struct nouveau_channel *chan)
 {
         struct drm_device *dev = chan->dev;
         struct drm_nouveau_private *dev_priv = dev->dev_private;
+        unsigned long flags;
         int ret;
 
         ret = nouveau_gpuobj_new_fake(dev, NV04_RAMFC(chan->id), ~0,
@@ -127,6 +128,8 @@ nv04_fifo_create_context(struct nouveau_channel *chan)
         if (ret)
                 return ret;
 
+        spin_lock_irqsave(&dev_priv->context_switch_lock, flags);
+
         /* Setup initial state */
         dev_priv->engine.instmem.prepare_access(dev, true);
         RAMFC_WR(DMA_PUT, chan->pushbuf_base);
@@ -144,6 +147,8 @@ nv04_fifo_create_context(struct nouveau_channel *chan)
         /* enable the fifo dma operation */
         nv_wr32(dev, NV04_PFIFO_MODE,
                 nv_rd32(dev, NV04_PFIFO_MODE) | (1 << chan->id));
+
+        spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
         return 0;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nv40_fifo.c b/drivers/gpu/drm/nouveau/nv40_fifo.c
index b4f19ccb8b41..6b2ef4a9fce1 100644
--- a/drivers/gpu/drm/nouveau/nv40_fifo.c
+++ b/drivers/gpu/drm/nouveau/nv40_fifo.c
@@ -37,6 +37,7 @@ nv40_fifo_create_context(struct nouveau_channel *chan)
         struct drm_device *dev = chan->dev;
         struct drm_nouveau_private *dev_priv = dev->dev_private;
         uint32_t fc = NV40_RAMFC(chan->id);
+        unsigned long flags;
         int ret;
 
         ret = nouveau_gpuobj_new_fake(dev, NV40_RAMFC(chan->id), ~0,
@@ -45,6 +46,8 @@ nv40_fifo_create_context(struct nouveau_channel *chan)
         if (ret)
                 return ret;
 
+        spin_lock_irqsave(&dev_priv->context_switch_lock, flags);
+
         dev_priv->engine.instmem.prepare_access(dev, true);
         nv_wi32(dev, fc +  0, chan->pushbuf_base);
         nv_wi32(dev, fc +  4, chan->pushbuf_base);
@@ -63,6 +66,8 @@ nv40_fifo_create_context(struct nouveau_channel *chan)
         /* enable the fifo dma operation */
         nv_wr32(dev, NV04_PFIFO_MODE,
                 nv_rd32(dev, NV04_PFIFO_MODE) | (1 << chan->id));
+
+        spin_unlock_irqrestore(&dev_priv->context_switch_lock, flags);
         return 0;
 }
 
diff --git a/drivers/gpu/drm/nouveau/nv50_fifo.c b/drivers/gpu/drm/nouveau/nv50_fifo.c
index 204a79ff10f4..369ecb4cee57 100644
--- a/drivers/gpu/drm/nouveau/nv50_fifo.c
+++ b/drivers/gpu/drm/nouveau/nv50_fifo.c
@@ -243,6 +243,7 @@ nv50_fifo_create_context(struct nouveau_channel *chan)