5 files changed, 36 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
index ee237043c302..9ddcae9b3997 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
@@ -941,7 +941,11 @@ i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
 		dsm_size = ALIGN_DOWN(lmem_size - dsm_base, SZ_1M);
 	}
 
-	if (pci_resource_len(pdev, GEN12_LMEM_BAR) < lmem_size) {
+	if (i915_direct_stolen_access(i915)) {
+		drm_dbg(&i915->drm, "Using direct DSM access\n");
+		io_start = intel_uncore_read64(uncore, GEN12_DSMBASE) & GEN12_BDSM_MASK;
+		io_size = dsm_size;
+	} else if (pci_resource_len(pdev, GEN12_LMEM_BAR) < lmem_size) {
 		io_start = 0;
 		io_size = 0;
 	} else {
diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
index 21a7e3191c18..bce5d8025340 100644
--- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
@@ -24,6 +24,7 @@
 #include "intel_ring.h"
 #include "i915_drv.h"
 #include "i915_pci.h"
+#include "i915_reg.h"
 #include "i915_request.h"
 #include "i915_scatterlist.h"
 #include "i915_utils.h"
@@ -1152,13 +1153,20 @@ static unsigned int gen6_gttadr_offset(struct drm_i915_private *i915)
 static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size)
 {
 	struct drm_i915_private *i915 = ggtt->vm.i915;
+	struct intel_uncore *uncore = ggtt->vm.gt->uncore;
 	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
 	phys_addr_t phys_addr;
 	u32 pte_flags;
 	int ret;
 
 	GEM_WARN_ON(pci_resource_len(pdev, GEN4_GTTMMADR_BAR) != gen6_gttmmadr_size(i915));
-	phys_addr = pci_resource_start(pdev, GEN4_GTTMMADR_BAR) + gen6_gttadr_offset(i915);
+
+	if (i915_direct_stolen_access(i915)) {
+		drm_dbg(&i915->drm, "Using direct GSM access\n");
+		phys_addr = intel_uncore_read64(uncore, GEN12_GSMBASE) & GEN12_BDSM_MASK;
+	} else {
+		phys_addr = pci_resource_start(pdev, GEN4_GTTMMADR_BAR) + gen6_gttadr_offset(i915);
+	}
 
 	if (needs_wc_ggtt_mapping(i915))
 		ggtt->gsm = ioremap_wc(phys_addr, size);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 0b9e018256c7..c1bf70d62ead 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5414,6 +5414,9 @@
 #define   GEN6_PCODE_FREQ_RING_RATIO_SHIFT	16
 #define GEN6_PCODE_DATA1			_MMIO(0x13812C)
 
+#define MTL_PCODE_STOLEN_ACCESS			_MMIO(0x138914)
+#define   STOLEN_ACCESS_ALLOWED			0x1
+
 /* IVYBRIDGE DPF */
 #define GEN7_L3CDERRST1(slice)		_MMIO(0xB008 + (slice) * 0x200) /* L3CD Error Status 1 */
 #define   GEN7_L3CDERRST1_ROW_MASK	(0x7ff << 14)
diff --git a/drivers/gpu/drm/i915/i915_utils.c b/drivers/gpu/drm/i915/i915_utils.c
index 29fd02bf5ea8..6f9e7b354b54 100644
--- a/drivers/gpu/drm/i915/i915_utils.c
+++ b/drivers/gpu/drm/i915/i915_utils.c
@@ -8,6 +8,7 @@
 #include <drm/drm_drv.h>
 
 #include "i915_drv.h"
+#include "i915_reg.h"
 #include "i915_utils.h"
 
 #define FDO_BUG_MSG "Please file a bug on drm/i915; see " FDO_BUG_URL " for details."
@@ -125,3 +126,19 @@ bool i915_vtd_active(struct drm_i915_private *i915)
 	/* Running as a guest, we assume the host is enforcing VT'd */
 	return i915_run_as_guest();
 }
+
+bool i915_direct_stolen_access(struct drm_i915_private *i915)
+{
+	/*
+	 * Wa_22018444074
+	 *
+	 * Access via BAR can hang MTL, go directly to GSM/DSM,
+	 * except for VM guests which won't have access to it.
+	 *
+	 * Normally this would not work but on MTL the system firmware
+	 * should have relaxed the access permissions sufficiently.
+	 * 0x138914==0x1 indicates that the firmware has done its job.
+	 */
+	return IS_METEORLAKE(i915) && !i915_run_as_guest() &&
+		intel_uncore_read(&i915->uncore, MTL_PCODE_STOLEN_ACCESS) == STOLEN_ACCESS_ALLOWED;
+}
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index f98577967b7f..b45ef0560611 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -391,4 +391,6 @@ static inline bool i915_run_as_guest(void)
 
 bool i915_vtd_active(struct drm_i915_private *i915);
 
+bool i915_direct_stolen_access(struct drm_i915_private *i915);
+
 #endif /* !__I915_UTILS_H */