drm/xe: Prepare for running in different SR-IOV modes

We will be adding support for the SR-IOV and driver might be then
running, in addition to existing non-virtualized bare-metal mode,
also in Physical Function (PF) or Virtual Function (VF) mode.

Since these additional modes require some changes to the driver,
define enum flag to represent different SR-IOV modes and add a
function where we will detect the actual mode in the runtime.

We start with a forced bare-metal mode as it is sufficient to
enable basic functionality and ensures no impact to existing code.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20231115073804.1861-2-michal.wajdeczko@intel.com
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/Makefile

@@ -122,6 +122,9 @@ xe-y += xe_bb.o \
 # graphics hardware monitoring (HWMON) support
 xe-$(CONFIG_HWMON) += xe_hwmon.o
 
+# graphics virtualization (SR-IOV) support
+xe-y += xe_sriov.o
+
 # i915 Display compat #defines and #includes
 subdir-ccflags-$(CONFIG_DRM_XE_DISPLAY) += \
 	-I$(srctree)/$(src)/display/ext \

drivers/gpu/drm/xe/xe_device_types.h

@@ -18,6 +18,7 @@
 #include "xe_platform_types.h"
 #include "xe_pt_types.h"
 #include "xe_pmu.h"
+#include "xe_sriov_types.h"
 #include "xe_step_types.h"
 
 #if IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
@@ -299,6 +300,12 @@ struct xe_device {
 		struct ttm_resource_manager sys_mgr;
 	} mem;
 
+	/** @sriov: device level virtualization data */
+	struct {
+		/** @sriov.__mode: SR-IOV mode (Don't access directly!) */
+		enum xe_sriov_mode __mode;
+	} sriov;
+
 	/** @usm: unified memory state */
 	struct {
 		/** @asid: convert a ASID to VM */

drivers/gpu/drm/xe/xe_pci.c

@@ -24,6 +24,7 @@
 #include "xe_module.h"
 #include "xe_pci_types.h"
 #include "xe_pm.h"
+#include "xe_sriov.h"
 #include "xe_step.h"
 
 enum toggle_d3cold {
@@ -705,6 +706,8 @@ static int xe_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 
 	pci_set_master(pdev);
 
+	xe_sriov_probe_early(xe, desc->has_sriov);
+
 	err = xe_info_init(xe, desc, subplatform_desc);
 	if (err)
 		goto err_pci_disable;

drivers/gpu/drm/xe/xe_sriov.c

@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#include "xe_assert.h"
+#include "xe_sriov.h"
+
+/**
+ * xe_sriov_mode_to_string - Convert enum value to string.
+ * @mode: the &xe_sriov_mode to convert
+ *
+ * Returns: SR-IOV mode as a user friendly string.
+ */
+const char *xe_sriov_mode_to_string(enum xe_sriov_mode mode)
+{
+	switch (mode) {
+	case XE_SRIOV_MODE_NONE:
+		return "none";
+	case XE_SRIOV_MODE_PF:
+		return "SR-IOV PF";
+	case XE_SRIOV_MODE_VF:
+		return "SR-IOV VF";
+	default:
+		return "<invalid>";
+	}
+}
+
+/**
+ * xe_sriov_probe_early - Probe a SR-IOV mode.
+ * @xe: the &xe_device to probe mode on
+ * @has_sriov: flag indicating hardware support for SR-IOV
+ *
+ * This function should be called only once and as soon as possible during
+ * driver probe to detect whether we are running a SR-IOV Physical Function
+ * (PF) or a Virtual Function (VF) device.
+ *
+ * SR-IOV PF mode detection is based on PCI @dev_is_pf() function.
+ * SR-IOV VF mode detection is based on dedicated MMIO register read.
+ */
+void xe_sriov_probe_early(struct xe_device *xe, bool has_sriov)
+{
+	enum xe_sriov_mode mode = XE_SRIOV_MODE_NONE;
+
+	/* TODO: replace with proper mode detection */
+	xe_assert(xe, !has_sriov);
+
+	xe_assert(xe, !xe->sriov.__mode);
+	xe->sriov.__mode = mode;
+	xe_assert(xe, xe->sriov.__mode);
+
+	if (has_sriov)
+		drm_info(&xe->drm, "Running in %s mode\n",
+			 xe_sriov_mode_to_string(xe_device_sriov_mode(xe)));
+}

drivers/gpu/drm/xe/xe_sriov.h

@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#ifndef _XE_SRIOV_H_
+#define _XE_SRIOV_H_
+
+#include "xe_assert.h"
+#include "xe_device_types.h"
+#include "xe_sriov_types.h"
+
+const char *xe_sriov_mode_to_string(enum xe_sriov_mode mode);
+
+void xe_sriov_probe_early(struct xe_device *xe, bool has_sriov);
+
+static inline enum xe_sriov_mode xe_device_sriov_mode(struct xe_device *xe)
+{
+	xe_assert(xe, xe->sriov.__mode);
+	return xe->sriov.__mode;
+}
+
+static inline bool xe_device_is_sriov_pf(struct xe_device *xe)
+{
+	return xe_device_sriov_mode(xe) == XE_SRIOV_MODE_PF;
+}
+
+static inline bool xe_device_is_sriov_vf(struct xe_device *xe)
+{
+	return xe_device_sriov_mode(xe) == XE_SRIOV_MODE_VF;
+}
+
+#ifdef CONFIG_PCI_IOV
+#define IS_SRIOV_PF(xe) xe_device_is_sriov_pf(xe)
+#else
+#define IS_SRIOV_PF(xe) (typecheck(struct xe_device *, (xe)) && false)
+#endif
+#define IS_SRIOV_VF(xe) xe_device_is_sriov_vf(xe)
+
+#define IS_SRIOV(xe) (IS_SRIOV_PF(xe) || IS_SRIOV_VF(xe))
+
+#endif

drivers/gpu/drm/xe/xe_sriov_types.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#ifndef _XE_SRIOV_TYPES_H_
+#define _XE_SRIOV_TYPES_H_
+
+#include <linux/build_bug.h>
+
+/**
+ * enum xe_sriov_mode - SR-IOV mode
+ * @XE_SRIOV_MODE_NONE: bare-metal mode (non-virtualized)
+ * @XE_SRIOV_MODE_PF: SR-IOV Physical Function (PF) mode
+ * @XE_SRIOV_MODE_VF: SR-IOV Virtual Function (VF) mode
+ */
+enum xe_sriov_mode {
+	/*
+	 * Note: We don't use default enum value 0 to allow catch any too early
+	 * attempt of checking the SR-IOV mode prior to the actual mode probe.
+	 */
+	XE_SRIOV_MODE_NONE = 1,
+	XE_SRIOV_MODE_PF,
+	XE_SRIOV_MODE_VF,
+};
+static_assert(XE_SRIOV_MODE_NONE);
+
+#endif