From 6e90293618ed476d6b11f82ce724efbb9e9a071b Mon Sep 17 00:00:00 2001
From: Zack Rusin <zackr@vmware.com>
Date: Thu, 1 Dec 2022 12:53:41 -0500
Subject: [PATCH] drm/vmwgfx: Don't use screen objects when SEV is active
Git-commit: 6e90293618ed476d6b11f82ce724efbb9e9a071b
Patch-mainline: v6.1
References: git-fixes

When SEV is enabled gmr's and mob's are explicitly disabled because
the encrypted system memory can not be used by the hypervisor.

The driver was disabling GMR's but the presentation code, which depends
on GMR's, wasn't honoring it which lead to black screen on hosts
with SEV enabled.

Make sure screen objects presentation is not used when guest memory
regions have been disabled to fix presentation on SEV enabled hosts.

Fixes: 3b0d6458c705 ("drm/vmwgfx: Refuse DMA operation when SEV encryption is active")
Cc: <stable@vger.kernel.org> # v5.7+
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reported-by: Nicholas Hunt <nhunt@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221201175341.491884-1-zack@kde.org
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c
@@ -953,6 +953,10 @@ int vmw_kms_sou_init_display(struct vmw_
 	struct drm_device *dev = &dev_priv->drm;
 	int i, ret;
 
+	/* Screen objects won't work if GMR's aren't available */
+	if (!dev_priv->has_gmr)
+		return -ENOSYS;
+
 	if (!(dev_priv->capabilities & SVGA_CAP_SCREEN_OBJECT_2)) {
 		DRM_INFO("Not using screen objects,"
 			 " missing cap SCREEN_OBJECT_2\n");