[Intel-xe] [PATCH v2 09/10] drm/xe: Carve out top of DSM as reserved

[Lucas De Marchi]

Top of DSM contains the WOPCM where kernel driver shouldn't access as
it contains data from other HW agents. Carve it out from the stolen
memory. On a MTL system, the output now matches the expected values:

Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
---
 drivers/gpu/drm/xe/regs/xe_regs.h      | 3 +++
 drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c | 8 +++++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/regs/xe_regs.h b/drivers/gpu/drm/xe/regs/xe_regs.h
index dbf572d11af0..315f6f8dadf3 100644
--- a/drivers/gpu/drm/xe/regs/xe_regs.h
+++ b/drivers/gpu/drm/xe/regs/xe_regs.h
@@ -84,4 +84,7 @@
 #define DSMBASE					XE_REG(0x1080C0)
 #define   BDSM_MASK				REG_GENMASK64(63, 20)
 
+#define STOLEN_RESERVED				XE_REG(0x1082c0)
+#define   WOPCM_SIZE_MASK			REG_GENMASK64(8, 7)
+
 #endif
diff --git a/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c b/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
index 271b3fba4129..7bba8fff5a5d 100644
--- a/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
+++ b/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
@@ -89,7 +89,7 @@ static s64 detect_bar2_dgfx(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
 static u32 detect_bar2_integrated(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
 {
 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
-	u32 stolen_size;
+	u32 stolen_size, wopcm_size;
 	u32 ggc, gms;
 
 	ggc = xe_mmio_read32(xe_root_mmio_gt(xe), GGC);
@@ -124,6 +124,12 @@ static u32 detect_bar2_integrated(struct xe_device *xe, struct xe_ttm_stolen_mgr
 		return 0;
 	}
 
+	/* Carve out the top of DSM as it contains the reserved WOPCM region */
+	wopcm_size = REG_FIELD_GET64(WOPCM_SIZE_MASK,
+				     xe_mmio_read64(xe_root_mmio_gt(xe),
+						    STOLEN_RESERVED));
+	stolen_size -= (1U << wopcm_size) * SZ_1M;
+
 	if (drm_WARN_ON(&xe->drm, stolen_size + SZ_8M > pci_resource_len(pdev, 2)))
 		return 0;
 
-- 
2.40.1