drm/i915: Bypass LMEMBAR/GTTMMADR for MTL stolen memory access

From Ville Syrjala
c08c364102d07288610734de34111a666e730ae7 in mainline linux

5 files changed, 45 insertions, 4 deletions

diff --git a/sys/dev/pci/drm/i915/gem/i915_gem_stolen.c b/sys/dev/pci/drm/i915/gem/i915_gem_stolen.c
index b8a19413320..1fdadbd45e8 100644
--- a/sys/dev/pci/drm/i915/gem/i915_gem_stolen.c
+++ b/sys/dev/pci/drm/i915/gem/i915_gem_stolen.c
@@ -990,8 +990,12 @@ i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
 		dsm_size = ALIGN_DOWN(lmem_size - dsm_base, SZ_1M);
 	}
 
+	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;
 #ifdef __linux__
-	if (pci_resource_len(pdev, GEN12_LMEM_BAR) < lmem_size) {
+	} else if (pci_resource_len(pdev, GEN12_LMEM_BAR) < lmem_size) {
 		io_start = 0;
 		io_size = 0;
 	} else {
@@ -999,7 +1003,7 @@ i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
 		io_size = dsm_size;
 	}
 #else
-	if (lmem_len < lmem_size) {
+	} else if (lmem_len < lmem_size) {
 		io_start = 0;
 		io_size = 0;
 	} else {
diff --git a/sys/dev/pci/drm/i915/gt/intel_ggtt.c b/sys/dev/pci/drm/i915/gt/intel_ggtt.c
index 2860d397f8e..14818a3d20b 100644
--- a/sys/dev/pci/drm/i915/gt/intel_ggtt.c
+++ b/sys/dev/pci/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"
@@ -1171,13 +1172,20 @@ 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);
@@ -1216,6 +1224,7 @@ static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size)
 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 = i915->drm.pdev;
 	phys_addr_t phys_addr;
 	bus_addr_t addr;
@@ -1232,7 +1241,13 @@ static int ggtt_probe_common(struct i915_ggtt *ggtt, u64 size)
 		return ret;
 
 	GEM_WARN_ON(len != gen6_gttmmadr_size(i915));
-	phys_addr = addr + 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 = addr + gen6_gttadr_offset(i915);
+	}
 
 	if (needs_wc_ggtt_mapping(i915))
 		flags = BUS_SPACE_MAP_PREFETCHABLE;
diff --git a/sys/dev/pci/drm/i915/i915_reg.h b/sys/dev/pci/drm/i915/i915_reg.h
index aefad14ab27..386286356d2 100644
--- a/sys/dev/pci/drm/i915/i915_reg.h
+++ b/sys/dev/pci/drm/i915/i915_reg.h
@@ -5452,6 +5452,9 @@
 #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/sys/dev/pci/drm/i915/i915_utils.c b/sys/dev/pci/drm/i915/i915_utils.c
index d742c01214e..95a95731d7d 100644
--- a/sys/dev/pci/drm/i915/i915_utils.c
+++ b/sys/dev/pci/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"
 
 #include <sys/syslog.h>
@@ -138,3 +139,19 @@ bool i915_vtd_active(struct drm_i915_private *i915)
 	return i915_run_as_guest();
 #endif
 }
+
+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/sys/dev/pci/drm/i915/i915_utils.h b/sys/dev/pci/drm/i915/i915_utils.h
index 026fdb3ed1c..4ee6a182ac1 100644
--- a/sys/dev/pci/drm/i915/i915_utils.h
+++ b/sys/dev/pci/drm/i915/i915_utils.h
@@ -401,4 +401,6 @@ 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 */