drm/vmwgfx: Implement virtual kms

By default vmwgfx doesn't support vblanking or crc generation which
makes it impossible to use various IGT tests to validate vmwgfx.
Implement virtual kernel mode setting, which is mainly related to
simulated vblank support.

Code is very similar to amd's vkms and the vkms module itself, except
that it's integrated with vmwgfx three different output technologies -
legacy, screen object and screen targets.

Make IGT's kms_vblank pass on vmwgfx and allows a lot of other IGT
tests to run with vmwgfx.

Support for vkms needs to be manually enabled by adding:
guestinfo.vmwgfx.vkms_enable = "TRUE"
somewhere in the vmx file, otherwise it's off by default.

Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Acked-by: Martin Krastev <martin.krastev@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240412025511.78553-2-zack.rusin@broadcom.com

1 files changed, 193 insertions, 0 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c
new file mode 100644
index 000000000000..ff76bfd70f91
--- /dev/null
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_vkms.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/**************************************************************************
+ *
+ * Copyright (c) 2024 Broadcom. All Rights Reserved. The term
+ * “Broadcom” refers to Broadcom Inc. and/or its subsidiaries.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#include "vmwgfx_vkms.h"
+
+#include "vmwgfx_drv.h"
+#include "vmwgfx_kms.h"
+#include "vmwgfx_vkms.h"
+
+#include <drm/drm_crtc.h>
+#include <drm/drm_print.h>
+#include <drm/drm_vblank.h>
+
+#define GUESTINFO_VBLANK  "guestinfo.vmwgfx.vkms_enable"
+
+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;
+	u64 ret_overrun;
+	bool 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__);
+
+	ret = drm_crtc_handle_vblank(crtc);
+	/* Don't queue timer again when vblank is disabled. */
+	if (!ret)
+		return HRTIMER_NORESTART;
+
+	return HRTIMER_RESTART;
+}
+
+void
+vmw_vkms_init(struct vmw_private *vmw)
+{
+	char buffer[64];
+	const size_t max_buf_len = sizeof(buffer) - 1;
+	size_t buf_len = max_buf_len;
+	int ret;
+
+	vmw->vkms_enabled = false;
+
+	ret = vmw_host_get_guestinfo(GUESTINFO_VBLANK, buffer, &buf_len);
+	if (ret || buf_len > max_buf_len)
+		return;
+	buffer[buf_len] = '\0';
+
+	ret = kstrtobool(buffer, &vmw->vkms_enabled);
+	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);
+	}
+}
+
+bool
+vmw_vkms_get_vblank_timestamp(struct drm_crtc *crtc,
+			      int *max_error,
+			      ktime_t *vblank_time,
+			      bool in_vblank_irq)
+{
+	struct drm_device *dev = crtc->dev;
+	struct vmw_private *vmw = vmw_priv(dev);
+	unsigned int pipe = crtc->index;
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+
+	if (!vmw->vkms_enabled)
+		return false;
+
+	if (!READ_ONCE(vblank->enabled)) {
+		*vblank_time = ktime_get();
+		return true;
+	}
+
+	*vblank_time = READ_ONCE(du->vkms.timer.node.expires);
+
+	if (WARN_ON(*vblank_time == vblank->time))
+		return true;
+
+	/*
+	 * To prevent races we roll the hrtimer forward before we do any
+	 * interrupt processing - this is how real hw works (the interrupt is
+	 * only generated after all the vblank registers are updated) and what
+	 * the vblank core expects. Therefore we need to always correct the
+	 * timestampe by one frame.
+	 */
+	*vblank_time -= du->vkms.period_ns;
+
+	return true;
+}
+
+int
+vmw_vkms_enable_vblank(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct vmw_private *vmw = vmw_priv(dev);
+	unsigned int pipe = drm_crtc_index(crtc);
+	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+
+	if (!vmw->vkms_enabled)
+		return -EINVAL;
+
+	drm_calc_timestamping_constants(crtc, &crtc->mode);
+
+	du->vkms.period_ns = ktime_set(0, vblank->framedur_ns);
+	hrtimer_start(&du->vkms.timer, du->vkms.period_ns, HRTIMER_MODE_REL);
+
+	return 0;
+}
+
+void
+vmw_vkms_disable_vblank(struct drm_crtc *crtc)
+{
+	struct vmw_display_unit *du = vmw_crtc_to_du(crtc);
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (!vmw->vkms_enabled)
+		return;
+
+	hrtimer_try_to_cancel(&du->vkms.timer);
+}
+
+void
+vmw_vkms_crtc_atomic_flush(struct drm_crtc *crtc,
+			   struct drm_atomic_state *state)
+{
+	unsigned long flags;
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (vmw->vkms_enabled && crtc->state->event) {
+		spin_lock_irqsave(&crtc->dev->event_lock, flags);
+
+		if (drm_crtc_vblank_get(crtc) != 0)
+			drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		else
+			drm_crtc_arm_vblank_event(crtc, crtc->state->event);
+
+		spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
+
+		crtc->state->event = NULL;
+	}
+}
+
+void
+vmw_vkms_crtc_atomic_enable(struct drm_crtc *crtc,
+			    struct drm_atomic_state *state)
+{
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (vmw->vkms_enabled)
+		drm_crtc_vblank_on(crtc);
+}
+
+void
+vmw_vkms_crtc_atomic_disable(struct drm_crtc *crtc,
+			     struct drm_atomic_state *state)
+{
+	struct vmw_private *vmw = vmw_priv(crtc->dev);
+
+	if (vmw->vkms_enabled)
+		drm_crtc_vblank_off(crtc);
+}