drm/vmwgfx: Implement virtual crc generation

crc checksums are used to validate the output. Normally they're part
of the actual display hardware but on virtual stack there's nothing
to automatically generate them.

Implement crc generation for the vmwgfx stack. This works only on
screen targets, where it's possibly to easily make sure that the
guest side contents of the surface matches the host sides output.

Just like the vblank support, crc generation can only be enabled via:
guestinfo.vmwgfx.vkms_enable = "TRUE"
option in the vmx file.

Makes IGT's kms_pipe_crc_basic pass and allows a huge number of other
IGT tests which require CRC generation of the output to actually run
on vmwgfx. Makes it possible to actually validate a lof of the kms and
drm functionality with vmwgfx.

Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Acked-by: Martin Krastev <martin.krastev@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412025511.78553-3-zack.rusin@broadcom.com

1 files changed, 448 insertions, 9 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c
index ff76bfd70f91..7e93a45948f7 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c
@@ -28,33 +28,179 @@
 
 #include "vmwgfx_vkms.h"
 
+#include "vmwgfx_bo.h"
 #include "vmwgfx_drv.h"
 #include "vmwgfx_kms.h"
 #include "vmwgfx_vkms.h"
 
+#include "vmw_surface_cache.h"
+
 #include <drm/drm_crtc.h>
+#include <drm/drm_debugfs_crc.h>
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 
+#include <linux/crc32.h>
+#include <linux/delay.h>
+
 #define GUESTINFO_VBLANK  "guestinfo.vmwgfx.vkms_enable"
 
-enum hrtimer_restart
+static int
+vmw_surface_sync(struct vmw_private *vmw,
+		 struct vmw_surface *surf)
+{
+	int ret;
+	struct vmw_fence_obj *fence = NULL;
+	struct vmw_bo *bo = surf->res.guest_memory_bo;
+
+	vmw_resource_clean(&surf->res);
+
+	ret = ttm_bo_reserve(&bo->tbo, false, false, NULL);
+	if (ret != 0) {
+		drm_warn(&vmw->drm, "%s: failed reserve\n", __func__);
+		goto done;
+	}
+
+	ret = vmw_execbuf_fence_commands(NULL, vmw, &fence, NULL);
+	if (ret != 0) {
+		drm_warn(&vmw->drm, "%s: failed execbuf\n", __func__);
+		ttm_bo_unreserve(&bo->tbo);
+		goto done;
+	}
+
+	dma_fence_wait(&fence->base, false);
+	dma_fence_put(&fence->base);
+
+	ttm_bo_unreserve(&bo->tbo);
+done:
+	return ret;
+}
+
+static int
+compute_crc(struct drm_crtc *crtc,
+	    struct vmw_surface *surf,
+	    u32 *crc)
+{
+	u8 *mapped_surface;
+	struct vmw_bo *bo = surf->res.guest_memory_bo;
+	const struct SVGA3dSurfaceDesc *desc =
+		vmw_surface_get_desc(surf->metadata.format);
+	u32 row_pitch_bytes;
+	SVGA3dSize blocks;
+	u32 y;
+
+	*crc = 0;
+
+	vmw_surface_get_size_in_blocks(desc, &surf->metadata.base_size, &blocks);
+	row_pitch_bytes = blocks.width * desc->pitchBytesPerBlock;
+	WARN_ON(!bo);
+	mapped_surface = vmw_bo_map_and_cache(bo);
+
+	for (y = 0; y < blocks.height; y++) {
+		*crc = crc32_le(*crc, mapped_surface, row_pitch_bytes);
+		mapped_surface += row_pitch_bytes;
+	}
+
+	vmw_bo_unmap(bo);
+
+	return 0;
+}
+
+static void
+crc_generate_worker(struct work_struct *work)
+{
+	struct vmw_display_unit *du =
+		container_of(work, struct vmw_display_unit, vkms.crc_generator_work);
+	struct drm_crtc *crtc = &du->crtc;
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+	bool crc_pending;
+	u64 frame_start, frame_end;
+	u32 crc32 = 0;
+	struct vmw_surface *surf = 0;
+	int ret;
+
+	spin_lock_irq(&du->vkms.crc_state_lock);
+	crc_pending = du->vkms.crc_pending;
+	spin_unlock_irq(&du->vkms.crc_state_lock);
+
+	/*
+	 * We raced with the vblank hrtimer and previous work already computed
+	 * the crc, nothing to do.
+	 */
+	if (!crc_pending)
+		return;
+
+	spin_lock_irq(&du->vkms.crc_state_lock);
+	surf = du->vkms.surface;
+	spin_unlock_irq(&du->vkms.crc_state_lock);
+
+	if (vmw_surface_sync(vmw, surf)) {
+		drm_warn(crtc->dev, "CRC worker wasn't able to sync the crc surface!\n");
+		return;
+	}
+
+	ret = compute_crc(crtc, surf, &crc32);
+	if (ret)
+		return;
+
+	spin_lock_irq(&du->vkms.crc_state_lock);
+	frame_start = du->vkms.frame_start;
+	frame_end = du->vkms.frame_end;
+	crc_pending = du->vkms.crc_pending;
+	du->vkms.frame_start = 0;
+	du->vkms.frame_end = 0;
+	du->vkms.crc_pending = false;
+	spin_unlock_irq(&du->vkms.crc_state_lock);
+
+	/*
+	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
+	 */
+	while (frame_start <= frame_end)
+		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
+}
+
+static enum hrtimer_restart
 vmw_vkms_vblank_simulate(struct hrtimer *timer)
 {
 	struct vmw_display_unit *du = container_of(timer, struct vmw_display_unit, vkms.timer);
 	struct drm_crtc *crtc = &du->crtc;
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+	struct vmw_surface *surf = NULL;
 	u64 ret_overrun;
-	bool ret;
+	bool locked, ret;
 
 	ret_overrun = hrtimer_forward_now(&du->vkms.timer,
 					  du->vkms.period_ns);
 	if (ret_overrun != 1)
-		DRM_WARN("%s: vblank timer overrun\n", __func__);
+		drm_dbg_driver(crtc->dev, "vblank timer missed %lld frames.\n",
+			       ret_overrun - 1);
 
+	locked = vmw_vkms_vblank_trylock(crtc);
 	ret = drm_crtc_handle_vblank(crtc);
-	/* Don't queue timer again when vblank is disabled. */
-	if (!ret)
-		return HRTIMER_NORESTART;
+	WARN_ON(!ret);
+	if (!locked)
+		return HRTIMER_RESTART;
+	surf = du->vkms.surface;
+	vmw_vkms_unlock(crtc);
+
+	if (du->vkms.crc_enabled && surf) {
+		u64 frame = drm_crtc_accurate_vblank_count(crtc);
+
+		spin_lock(&du->vkms.crc_state_lock);
+		if (!du->vkms.crc_pending)
+			du->vkms.frame_start = frame;
+		else
+			drm_dbg_driver(crtc->dev,
+				       "crc worker falling behind, frame_start: %llu, frame_end: %llu\n",
+				       du->vkms.frame_start, frame);
+		du->vkms.frame_end = frame;
+		du->vkms.crc_pending = true;
+		spin_unlock(&du->vkms.crc_state_lock);
+
+		ret = queue_work(vmw->crc_workq, &du->vkms.crc_generator_work);
+		if (!ret)
+			drm_dbg_driver(crtc->dev, "Composer worker already queued\n");
+	}
 
 	return HRTIMER_RESTART;
 }
@@ -78,8 +224,21 @@ vmw_vkms_init(struct vmw_private *vmw)
 	if (!ret && vmw->vkms_enabled) {
 		ret = drm_vblank_init(&vmw->drm, VMWGFX_NUM_DISPLAY_UNITS);
 		vmw->vkms_enabled = (ret == 0);
-		drm_info(&vmw->drm, "vkms_enabled = %d\n", vmw->vkms_enabled);
 	}
+
+	vmw->crc_workq = alloc_ordered_workqueue("vmwgfx_crc_generator", 0);
+	if (!vmw->crc_workq) {
+		drm_warn(&vmw->drm, "crc workqueue allocation failed. Disabling vkms.");
+		vmw->vkms_enabled = false;
+	}
+	if (vmw->vkms_enabled)
+		drm_info(&vmw->drm, "VKMS enabled\n");
+}
+
+void
+vmw_vkms_cleanup(struct vmw_private *vmw)
+{
+	destroy_workqueue(vmw->crc_workq);
 }
 
 bool
@@ -133,6 +292,8 @@ vmw_vkms_enable_vblank(struct drm_crtc *crtc)
 
 	drm_calc_timestamping_constants(crtc, &crtc->mode);
 
+	hrtimer_init(&du->vkms.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	du->vkms.timer.function = &vmw_vkms_vblank_simulate;
 	du->vkms.period_ns = ktime_set(0, vblank->framedur_ns);
 	hrtimer_start(&du->vkms.timer, du->vkms.period_ns, HRTIMER_MODE_REL);
 
@@ -148,7 +309,46 @@ vmw_vkms_disable_vblank(struct drm_crtc *crtc)
 	if (!vmw->vkms_enabled)
 		return;
 
-	hrtimer_try_to_cancel(&du->vkms.timer);
+	hrtimer_cancel(&du->vkms.timer);
+	du->vkms.surface = NULL;
+	du->vkms.period_ns = ktime_set(0, 0);
+}
+
+enum vmw_vkms_lock_state {
+	VMW_VKMS_LOCK_UNLOCKED     = 0,
+	VMW_VKMS_LOCK_MODESET      = 1,
+	VMW_VKMS_LOCK_VBLANK       = 2
+};
+
+void
+vmw_vkms_crtc_init(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+
+	atomic_set(&du->vkms.atomic_lock, VMW_VKMS_LOCK_UNLOCKED);
+	spin_lock_init(&du->vkms.crc_state_lock);
+
+	INIT_WORK(&du->vkms.crc_generator_work, crc_generate_worker);
+	du->vkms.surface = NULL;
+}
+
+void
+vmw_vkms_crtc_cleanup(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+
+	WARN_ON(work_pending(&du->vkms.crc_generator_work));
+	hrtimer_cancel(&du->vkms.timer);
+}
+
+void
+vmw_vkms_crtc_atomic_begin(struct drm_crtc *crtc,
+			   struct drm_atomic_state *state)
+{
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (vmw->vkms_enabled)
+		vmw_vkms_modeset_lock(crtc);
 }
 
 void
@@ -158,7 +358,10 @@ vmw_vkms_crtc_atomic_flush(struct drm_crtc *crtc,
 	unsigned long flags;
 	struct vmw_private *vmw = vmw_priv(crtc->dev);
 
-	if (vmw->vkms_enabled && crtc->state->event) {
+	if (!vmw->vkms_enabled)
+		return;
+
+	if (crtc->state->event) {
 		spin_lock_irqsave(&crtc->dev->event_lock, flags);
 
 		if (drm_crtc_vblank_get(crtc) != 0)
@@ -170,6 +373,8 @@ vmw_vkms_crtc_atomic_flush(struct drm_crtc *crtc,
 
 		crtc->state->event = NULL;
 	}
+
+	vmw_vkms_unlock(crtc);
 }
 
 void
@@ -191,3 +396,237 @@ vmw_vkms_crtc_atomic_disable(struct drm_crtc *crtc,
 	if (vmw->vkms_enabled)
 		drm_crtc_vblank_off(crtc);
 }
+
+static bool
+is_crc_supported(struct drm_crtc *crtc)
+{
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (!vmw->vkms_enabled)
+		return false;
+
+	if (vmw->active_display_unit != vmw_du_screen_target)
+		return false;
+
+	return true;
+}
+
+static const char * const pipe_crc_sources[] = {"auto"};
+
+static int
+crc_parse_source(const char *src_name,
+		 bool *enabled)
+{
+	int ret = 0;
+
+	if (!src_name) {
+		*enabled = false;
+	} else if (strcmp(src_name, "auto") == 0) {
+		*enabled = true;
+	} else {
+		*enabled = false;
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+const char *const *
+vmw_vkms_get_crc_sources(struct drm_crtc *crtc,
+			 size_t *count)
+{
+	*count = 0;
+	if (!is_crc_supported(crtc))
+		return NULL;
+
+	*count = ARRAY_SIZE(pipe_crc_sources);
+	return pipe_crc_sources;
+}
+
+int
+vmw_vkms_verify_crc_source(struct drm_crtc *crtc,
+			   const char *src_name,
+			   size_t *values_cnt)
+{
+	bool enabled;
+
+	if (!is_crc_supported(crtc))
+		return -EINVAL;
+
+	if (crc_parse_source(src_name, &enabled) < 0) {
+		drm_dbg_driver(crtc->dev, "unknown source '%s'\n", src_name);
+		return -EINVAL;
+	}
+
+	*values_cnt = 1;
+
+	return 0;
+}
+
+int
+vmw_vkms_set_crc_source(struct drm_crtc *crtc,
+			const char *src_name)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	bool enabled, prev_enabled, locked;
+	int ret;
+
+	if (!is_crc_supported(crtc))
+		return -EINVAL;
+
+	ret = crc_parse_source(src_name, &enabled);
+
+	if (enabled)
+		drm_crtc_vblank_get(crtc);
+
+	locked = vmw_vkms_modeset_lock_relaxed(crtc);
+	prev_enabled = du->vkms.crc_enabled;
+	du->vkms.crc_enabled = enabled;
+	if (locked)
+		vmw_vkms_unlock(crtc);
+
+	if (prev_enabled)
+		drm_crtc_vblank_put(crtc);
+
+	return ret;
+}
+
+void
+vmw_vkms_set_crc_surface(struct drm_crtc *crtc,
+			 struct vmw_surface *surf)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (vmw->vkms_enabled) {
+		WARN_ON(atomic_read(&du->vkms.atomic_lock) != VMW_VKMS_LOCK_MODESET);
+		du->vkms.surface = surf;
+	}
+}
+
+/**
+ * vmw_vkms_lock_max_wait_ns - Return the max wait for the vkms lock
+ * @du: The vmw_display_unit from which to grab the vblank timings
+ *
+ * Returns the maximum wait time used to acquire the vkms lock. By
+ * default uses a time of a single frame and in case where vblank
+ * was not initialized for the display unit 1/60th of a second.
+ */
+static inline u64
+vmw_vkms_lock_max_wait_ns(struct vmw_display_unit *du)
+{
+	s64 nsecs = ktime_to_ns(du->vkms.period_ns);
+
+	return  (nsecs > 0) ? nsecs : 16666666;
+}
+
+/**
+ * vmw_vkms_modeset_lock - Protects access to crtc during modeset
+ * @crtc: The crtc to lock for vkms
+ *
+ * This function prevents the VKMS timers/callbacks from being called
+ * while a modeset operation is in process. We don't want the callbacks
+ * e.g. the vblank simulator to be trying to access incomplete state
+ * so we need to make sure they execute only when the modeset has
+ * finished.
+ *
+ * Normally this would have been done with a spinlock but locking the
+ * entire atomic modeset with vmwgfx is impossible because kms prepare
+ * executes non-atomic ops (e.g. vmw_validation_prepare holds a mutex to
+ * guard various bits of state). Which means that we need to synchronize
+ * atomic context (the vblank handler) with the non-atomic entirity
+ * of kms - so use an atomic_t to track which part of vkms has access
+ * to the basic vkms state.
+ */
+void
+vmw_vkms_modeset_lock(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	const u64 nsecs_delay = 10;
+	const u64 MAX_NSECS_DELAY = vmw_vkms_lock_max_wait_ns(du);
+	u64 total_delay = 0;
+	int ret;
+
+	do {
+		ret = atomic_cmpxchg(&du->vkms.atomic_lock,
+				     VMW_VKMS_LOCK_UNLOCKED,
+				     VMW_VKMS_LOCK_MODESET);
+		if (ret == VMW_VKMS_LOCK_UNLOCKED || total_delay >= MAX_NSECS_DELAY)
+			break;
+		ndelay(nsecs_delay);
+		total_delay += nsecs_delay;
+	} while (1);
+
+	if (total_delay >= MAX_NSECS_DELAY) {
+		drm_warn(crtc->dev, "VKMS lock expired! total_delay = %lld, ret = %d, cur = %d\n",
+			 total_delay, ret, atomic_read(&du->vkms.atomic_lock));
+	}
+}
+
+/**
+ * vmw_vkms_modeset_lock_relaxed - Protects access to crtc during modeset
+ * @crtc: The crtc to lock for vkms
+ *
+ * Much like vmw_vkms_modeset_lock except that when the crtc is currently
+ * in a modeset it will return immediately.
+ *
+ * Returns true if actually locked vkms to modeset or false otherwise.
+ */
+bool
+vmw_vkms_modeset_lock_relaxed(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	const u64 nsecs_delay = 10;
+	const u64 MAX_NSECS_DELAY = vmw_vkms_lock_max_wait_ns(du);
+	u64 total_delay = 0;
+	int ret;
+
+	do {
+		ret = atomic_cmpxchg(&du->vkms.atomic_lock,
+				     VMW_VKMS_LOCK_UNLOCKED,
+				     VMW_VKMS_LOCK_MODESET);
+		if (ret == VMW_VKMS_LOCK_UNLOCKED ||
+		    ret == VMW_VKMS_LOCK_MODESET ||
+		    total_delay >= MAX_NSECS_DELAY)
+			break;
+		ndelay(nsecs_delay);
+		total_delay += nsecs_delay;
+	} while (1);
+
+	if (total_delay >= MAX_NSECS_DELAY) {
+		drm_warn(crtc->dev, "VKMS relaxed lock expired!\n");
+		return false;
+	}
+
+	return ret == VMW_VKMS_LOCK_UNLOCKED;
+}
+
+/**
+ * vmw_vkms_vblank_trylock - Protects access to crtc during vblank
+ * @crtc: The crtc to lock for vkms
+ *
+ * Tries to lock vkms for vblank, returns immediately.
+ *
+ * Returns true if locked vkms to vblank or false otherwise.
+ */
+bool
+vmw_vkms_vblank_trylock(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	u32 ret;
+
+	ret = atomic_cmpxchg(&du->vkms.atomic_lock,
+			     VMW_VKMS_LOCK_UNLOCKED,
+			     VMW_VKMS_LOCK_VBLANK);
+
+	return ret == VMW_VKMS_LOCK_UNLOCKED;
+}
+
+void
+vmw_vkms_unlock(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+
+	/* Release flag; mark it as unlocked. */
+	atomic_set(&du->vkms.atomic_lock, VMW_VKMS_LOCK_UNLOCKED);
+}