[PATCH v2 2/2] drm/msm: Add MSM_WAIT_IOVA ioctl

[Brian Ho]

Implements an ioctl to wait until a value at a given iova is greater
than or equal to a supplied value.

This will initially be used by turnip (open-source Vulkan driver for
QC in mesa) for occlusion queries where the userspace driver can
block on a query becoming available before continuing via
vkGetQueryPoolResults.

Signed-off-by: Brian Ho <brian at brkho.com>
---
 drivers/gpu/drm/msm/msm_drv.c | 61 +++++++++++++++++++++++++++++++++--
 include/uapi/drm/msm_drm.h    | 14 ++++++++
 2 files changed, 73 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index c84f0a8b3f2c..92853c795c5c 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -36,10 +36,11 @@
  *           MSM_GEM_INFO ioctl.
  * - 1.4.0 - softpin, MSM_RELOC_BO_DUMP, and GEM_INFO support to set/get
  *           GEM object's debug name
- * - 1.5.0 - Add SUBMITQUERY_QUERY ioctl
+ * - 1.5.0 - Add SUBMITQUEUE_QUERY ioctl
+ * - 1.6.0 - Add WAIT_IOVA ioctl
  */
 #define MSM_VERSION_MAJOR	1
-#define MSM_VERSION_MINOR	5
+#define MSM_VERSION_MINOR	6
 #define MSM_VERSION_PATCHLEVEL	0
 
 static const struct drm_mode_config_funcs mode_config_funcs = {
@@ -952,6 +953,61 @@ static int msm_ioctl_submitqueue_close(struct drm_device *dev, void *data,
 	return msm_submitqueue_remove(file->driver_priv, id);
 }
 
+static int msm_ioctl_wait_iova(struct drm_device *dev, void *data,
+		struct drm_file *file)
+{
+	struct msm_drm_private *priv = dev->dev_private;
+	struct drm_gem_object *obj;
+	struct drm_msm_wait_iova *args = data;
+	ktime_t timeout = to_ktime(args->timeout);
+	unsigned long remaining_jiffies = timeout_to_jiffies(&timeout);
+	struct msm_gpu *gpu = priv->gpu;
+	void *base_vaddr;
+	uint64_t ref_value = args->value & args->mask;
+	uint64_t *vaddr;
+	int ret;
+
+	if (args->pad)
+		return -EINVAL;
+
+	if (!gpu)
+		return -ENODEV;
+
+	obj = drm_gem_object_lookup(file, args->handle);
+	if (!obj)
+		return -ENOENT;
+
+	if (args->offset + sizeof(*vaddr) < args->offset ||
+		args->offset + sizeof(*vaddr) > obj->size) {
+		ret = -EINVAL;
+		goto err_put_gem_object;
+	}
+
+	base_vaddr = msm_gem_get_vaddr(obj);
+	if (IS_ERR(base_vaddr)) {
+		ret = PTR_ERR(base_vaddr);
+		goto err_put_gem_object;
+	}
+
+	vaddr = base_vaddr + args->offset;
+
+	/* TODO: Support 64 bit reference values with a flag. */
+	ret = wait_event_interruptible_timeout(gpu->event,
+			(int32_t)((uint32_t)*vaddr - (uint32_t)ref_value) >= 0,
+			remaining_jiffies);
+
+	if (ret == 0)
+		ret = -ETIMEDOUT;
+	else if (ret > 0)
+		ret = 0;
+
+    msm_gem_put_vaddr(obj);
+
+err_put_gem_object:
+	drm_gem_object_put_unlocked(obj);
+	return ret;
+}
+
 static const struct drm_ioctl_desc msm_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(MSM_GET_PARAM,    msm_ioctl_get_param,    DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(MSM_GEM_NEW,      msm_ioctl_gem_new,      DRM_RENDER_ALLOW),
@@ -964,6 +1020,7 @@ static const struct drm_ioctl_desc msm_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_NEW,   msm_ioctl_submitqueue_new,   DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_CLOSE, msm_ioctl_submitqueue_close, DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(MSM_SUBMITQUEUE_QUERY, msm_ioctl_submitqueue_query, DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(MSM_WAIT_IOVA, msm_ioctl_wait_iova, DRM_RENDER_ALLOW),
 };
 
 static const struct vm_operations_struct vm_ops = {
diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
index 0b85ed6a3710..d4eac312f56e 100644
--- a/include/uapi/drm/msm_drm.h
+++ b/include/uapi/drm/msm_drm.h
@@ -298,6 +298,18 @@ struct drm_msm_submitqueue_query {
 	__u32 pad;
 };
 
+/* This ioctl blocks until the value at bo + offset is greater than or equal
+ * to the reference value.
+ */
+struct drm_msm_wait_iova {
+	__u32 handle;          /* in, GEM handle */
+	__u32 pad;
+	struct drm_msm_timespec timeout;   /* in */
+	__u64 offset;          /* in, offset into bo */
+	__u64 mask;            /* in, mask of the value at bo + offset */
+	__u64 value;           /* in, reference value, 32 bits */
+};
+
 #define DRM_MSM_GET_PARAM              0x00
 /* placeholder:
 #define DRM_MSM_SET_PARAM              0x01
@@ -315,6 +327,7 @@ struct drm_msm_submitqueue_query {
 #define DRM_MSM_SUBMITQUEUE_NEW        0x0A
 #define DRM_MSM_SUBMITQUEUE_CLOSE      0x0B
 #define DRM_MSM_SUBMITQUEUE_QUERY      0x0C
+#define DRM_MSM_WAIT_IOVA      0x0D
 
 #define DRM_IOCTL_MSM_GET_PARAM        DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_GET_PARAM, struct drm_msm_param)
 #define DRM_IOCTL_MSM_GEM_NEW          DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_GEM_NEW, struct drm_msm_gem_new)
@@ -327,6 +340,7 @@ struct drm_msm_submitqueue_query {
 #define DRM_IOCTL_MSM_SUBMITQUEUE_NEW    DRM_IOWR(DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_NEW, struct drm_msm_submitqueue)
 #define DRM_IOCTL_MSM_SUBMITQUEUE_CLOSE  DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_CLOSE, __u32)
 #define DRM_IOCTL_MSM_SUBMITQUEUE_QUERY  DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_SUBMITQUEUE_QUERY, struct drm_msm_submitqueue_query)
+#define DRM_IOCTL_MSM_WAIT_IOVA        DRM_IOW (DRM_COMMAND_BASE + DRM_MSM_WAIT_IOVA, struct drm_msm_wait_iova)
 
 #if defined(__cplusplus)
 }
-- 
2.25.0.rc1.283.g88dfdc4193-goog