[PATCH 1/2] drm/xe: Align 64k scanout buffers physically when required

[Maarten Lankhorst]

For CCS formats on affected platforms, CCS can be used freely, but
display engine requires a multiple of 64k physical pages. No other
changes are needed.

At the BO creation time we don't know if the BO will be used for CCS
or not. If the scanout flag is set, and the BO is a multiple of 64k,
we take the safe route and force the physical alignment of 64k pages.

If the BO is not a multiple of 64k, or the scanout flag was not set
at BO creation, we reject it for usage as CCS in display. The physical
pages are likely not aligned correctly, and this will cause corruption
when used as FB.

Inspired by Zbigniews patch.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Co-developed-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
Cc: Matthew Auld <matthew.auld at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Juha-Pekka Heikkilä <juha-pekka.heikkila at intel.com>
---
 drivers/gpu/drm/xe/display/intel_fb_bo.c |  6 ++++++
 drivers/gpu/drm/xe/xe_bo.c               | 17 ++++++++++++++++-
 drivers/gpu/drm/xe/xe_device_types.h     |  1 +
 drivers/gpu/drm/xe/xe_vm.c               |  4 +++-
 4 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/display/intel_fb_bo.c b/drivers/gpu/drm/xe/display/intel_fb_bo.c
index f835492f73fb4..407367719abe2 100644
--- a/drivers/gpu/drm/xe/display/intel_fb_bo.c
+++ b/drivers/gpu/drm/xe/display/intel_fb_bo.c
@@ -7,6 +7,7 @@
 #include <drm/ttm/ttm_bo.h>
 
 #include "intel_display_types.h"
+#include "intel_fb.h"
 #include "intel_fb_bo.h"
 #include "xe_bo.h"
 
@@ -28,6 +29,11 @@ int intel_fb_bo_framebuffer_init(struct intel_framebuffer *intel_fb,
 	struct xe_device *xe = to_xe_device(bo->ttm.base.dev);
 	int ret;
 
+	if (XE_IOCTL_DBG(xe, intel_fb_is_ccs_modifier(mode_cmd->modifier[0]) &&
+			     (xe->info.vram_flags & XE_VRAM_FLAGS_DISPLAY_NEED64K_CCS) &&
+			     !(bo->flags & XE_BO_FLAG_NEEDS_64K)))
+		return -EINVAL;
+
 	xe_bo_get(bo);
 
 	ret = ttm_bo_reserve(&bo->ttm, true, false, NULL);
diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 6ed0e19552159..d9aa724db6c0b 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -2014,9 +2014,24 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
 	if (args->flags & DRM_XE_GEM_CREATE_FLAG_DEFER_BACKING)
 		bo_flags |= XE_BO_FLAG_DEFER_BACKING;
 
-	if (args->flags & DRM_XE_GEM_CREATE_FLAG_SCANOUT)
+	if (args->flags & DRM_XE_GEM_CREATE_FLAG_SCANOUT) {
 		bo_flags |= XE_BO_FLAG_SCANOUT;
 
+		/*
+		 * Since we don't know which buffer will be used for CCS,
+		 * we err on the safe side and force align the backing
+		 * VRAM to multiples of 64k.
+		 *
+		 * This only affects the physical placement of the pages,
+		 * and we still allow bo of other sizes, but they
+		 * cannot be used in CCS framebuffers due to alignment
+		 * issues.
+		 */
+		if ((xe->info.vram_flags & XE_VRAM_FLAGS_DISPLAY_NEED64K_CCS) &&
+		    !(args->size % SZ_64K))
+			bo_flags |= XE_BO_FLAG_NEEDS_64K;
+	}
+
 	bo_flags |= args->placement << (ffs(XE_BO_FLAG_SYSTEM) - 1);
 
 	if (args->flags & DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM) {
diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 5ed6f5434f42c..12ddab91a01c0 100644
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -47,6 +47,7 @@ struct xe_pat_ops;
 #define HAS_HECI_CSCFI(xe) ((xe)->info.has_heci_cscfi)
 
 #define XE_VRAM_FLAGS_NEED64K		BIT(0)
+#define XE_VRAM_FLAGS_DISPLAY_NEED64K_CCS	BIT(1)
 
 #define XE_GT0		0
 #define XE_GT1		1
diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
index d1bfd0b6e9558..bf3af8686167e 100644
--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -2878,7 +2878,9 @@ static int xe_vm_bind_ioctl_validate_bo(struct xe_device *xe, struct xe_bo *bo,
 		return -EINVAL;
 	}
 
-	if (bo->flags & XE_BO_FLAG_INTERNAL_64K) {
+	if ((bo->flags & XE_BO_FLAG_INTERNAL_64K) &&
+	    !(bo->flags & XE_BO_FLAG_SCANOUT &&
+	      xe->info.vram_flags & XE_VRAM_FLAGS_DISPLAY_NEED64K_CCS)) {
 		if (XE_IOCTL_DBG(xe, obj_offset &
 				 XE_64K_PAGE_MASK) ||
 		    XE_IOCTL_DBG(xe, addr & XE_64K_PAGE_MASK) ||
-- 
2.45.2