drm/xe/pf: Add support for encap/decap of bitstream to/from packet

Add debugfs handlers for migration state and handle bitstream
.read()/.write() to convert from bitstream to/from migration data
packets.
As descriptor/trailer are handled at this layer - add handling for both
save and restore side.

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patch.msgid.link/20251112132220.516975-8-michal.winiarski@intel.com
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>

drivers/gpu/drm/xe/xe_sriov_packet.c

@@ -8,6 +8,67 @@
 #include "xe_printk.h"
 #include "xe_sriov_packet.h"
 #include "xe_sriov_packet_types.h"
+#include "xe_sriov_pf_helpers.h"
+#include "xe_sriov_pf_migration.h"
+#include "xe_sriov_printk.h"
+
+static struct mutex *pf_migration_mutex(struct xe_device *xe, unsigned int vfid)
+{
+	xe_assert(xe, IS_SRIOV_PF(xe));
+	xe_assert(xe, vfid <= xe_sriov_pf_get_totalvfs(xe));
+
+	return &xe->sriov.pf.vfs[vfid].migration.lock;
+}
+
+static struct xe_sriov_packet **pf_pick_pending(struct xe_device *xe, unsigned int vfid)
+{
+	xe_assert(xe, IS_SRIOV_PF(xe));
+	xe_assert(xe, vfid <= xe_sriov_pf_get_totalvfs(xe));
+	lockdep_assert_held(pf_migration_mutex(xe, vfid));
+
+	return &xe->sriov.pf.vfs[vfid].migration.pending;
+}
+
+static struct xe_sriov_packet **
+pf_pick_descriptor(struct xe_device *xe, unsigned int vfid)
+{
+	xe_assert(xe, IS_SRIOV_PF(xe));
+	xe_assert(xe, vfid <= xe_sriov_pf_get_totalvfs(xe));
+	lockdep_assert_held(pf_migration_mutex(xe, vfid));
+
+	return &xe->sriov.pf.vfs[vfid].migration.descriptor;
+}
+
+static struct xe_sriov_packet **pf_pick_trailer(struct xe_device *xe, unsigned int vfid)
+{
+	xe_assert(xe, IS_SRIOV_PF(xe));
+	xe_assert(xe, vfid <= xe_sriov_pf_get_totalvfs(xe));
+	lockdep_assert_held(pf_migration_mutex(xe, vfid));
+
+	return &xe->sriov.pf.vfs[vfid].migration.trailer;
+}
+
+static struct xe_sriov_packet **pf_pick_read_packet(struct xe_device *xe,
+						    unsigned int vfid)
+{
+	struct xe_sriov_packet **data;
+
+	data = pf_pick_descriptor(xe, vfid);
+	if (*data)
+		return data;
+
+	data = pf_pick_pending(xe, vfid);
+	if (!*data)
+		*data = xe_sriov_pf_migration_save_consume(xe, vfid);
+	if (*data)
+		return data;
+
+	data = pf_pick_trailer(xe, vfid);
+	if (*data)
+		return data;
+
+	return NULL;
+}
 
 static bool pkt_needs_bo(struct xe_sriov_packet *data)
 {
@@ -135,3 +196,235 @@ int xe_sriov_packet_init_from_hdr(struct xe_sriov_packet *data)
 
 	return pkt_init(data);
 }
+
+static ssize_t pkt_hdr_read(struct xe_sriov_packet *data,
+			    char __user *buf, size_t len)
+{
+	loff_t offset = sizeof(data->hdr) - data->hdr_remaining;
+
+	if (!data->hdr_remaining)
+		return -EINVAL;
+
+	if (len > data->hdr_remaining)
+		len = data->hdr_remaining;
+
+	if (copy_to_user(buf, (void *)&data->hdr + offset, len))
+		return -EFAULT;
+
+	data->hdr_remaining -= len;
+
+	return len;
+}
+
+static ssize_t pkt_data_read(struct xe_sriov_packet *data,
+			     char __user *buf, size_t len)
+{
+	if (len > data->remaining)
+		len = data->remaining;
+
+	if (copy_to_user(buf, data->vaddr + (data->hdr.size - data->remaining), len))
+		return -EFAULT;
+
+	data->remaining -= len;
+
+	return len;
+}
+
+static ssize_t pkt_read_single(struct xe_sriov_packet **data,
+			       unsigned int vfid, char __user *buf, size_t len)
+{
+	ssize_t copied = 0;
+
+	if ((*data)->hdr_remaining)
+		copied = pkt_hdr_read(*data, buf, len);
+	else
+		copied = pkt_data_read(*data, buf, len);
+
+	if ((*data)->remaining == 0 && (*data)->hdr_remaining == 0) {
+		xe_sriov_packet_free(*data);
+		*data = NULL;
+	}
+
+	return copied;
+}
+
+/**
+ * xe_sriov_packet_read_single() - Read migration data from a single packet.
+ * @xe: the &xe_device
+ * @vfid: the VF identifier
+ * @buf: start address of userspace buffer
+ * @len: requested read size from userspace
+ *
+ * Return: number of bytes that has been successfully read,
+ *	   0 if no more migration data is available,
+ *	   -errno on failure.
+ */
+ssize_t xe_sriov_packet_read_single(struct xe_device *xe, unsigned int vfid,
+				    char __user *buf, size_t len)
+{
+	struct xe_sriov_packet **data = pf_pick_read_packet(xe, vfid);
+
+	if (!data)
+		return -ENODATA;
+	if (IS_ERR(*data))
+		return PTR_ERR(*data);
+
+	return pkt_read_single(data, vfid, buf, len);
+}
+
+static ssize_t pkt_hdr_write(struct xe_sriov_packet *data,
+			     const char __user *buf, size_t len)
+{
+	loff_t offset = sizeof(data->hdr) - data->hdr_remaining;
+	int ret;
+
+	if (len > data->hdr_remaining)
+		len = data->hdr_remaining;
+
+	if (copy_from_user((void *)&data->hdr + offset, buf, len))
+		return -EFAULT;
+
+	data->hdr_remaining -= len;
+
+	if (!data->hdr_remaining) {
+		ret = xe_sriov_packet_init_from_hdr(data);
+		if (ret)
+			return ret;
+	}
+
+	return len;
+}
+
+static ssize_t pkt_data_write(struct xe_sriov_packet *data,
+			      const char __user *buf, size_t len)
+{
+	if (len > data->remaining)
+		len = data->remaining;
+
+	if (copy_from_user(data->vaddr + (data->hdr.size - data->remaining), buf, len))
+		return -EFAULT;
+
+	data->remaining -= len;
+
+	return len;
+}
+
+/**
+ * xe_sriov_packet_write_single() - Write migration data to a single packet.
+ * @xe: the &xe_device
+ * @vfid: the VF identifier
+ * @buf: start address of userspace buffer
+ * @len: requested write size from userspace
+ *
+ * Return: number of bytes that has been successfully written,
+ *	   -errno on failure.
+ */
+ssize_t xe_sriov_packet_write_single(struct xe_device *xe, unsigned int vfid,
+				     const char __user *buf, size_t len)
+{
+	struct xe_sriov_packet **data = pf_pick_pending(xe, vfid);
+	int ret;
+	ssize_t copied;
+
+	if (IS_ERR_OR_NULL(*data)) {
+		*data = xe_sriov_packet_alloc(xe);
+		if (!*data)
+			return -ENOMEM;
+	}
+
+	if ((*data)->hdr_remaining)
+		copied = pkt_hdr_write(*data, buf, len);
+	else
+		copied = pkt_data_write(*data, buf, len);
+
+	if ((*data)->hdr_remaining == 0 && (*data)->remaining == 0) {
+		ret = xe_sriov_pf_migration_restore_produce(xe, vfid, *data);
+		if (ret) {
+			xe_sriov_packet_free(*data);
+			return ret;
+		}
+
+		*data = NULL;
+	}
+
+	return copied;
+}
+
+#define MIGRATION_DESCRIPTOR_DWORDS 0
+static size_t pf_descriptor_init(struct xe_device *xe, unsigned int vfid)
+{
+	struct xe_sriov_packet **desc = pf_pick_descriptor(xe, vfid);
+	struct xe_sriov_packet *data;
+	int ret;
+
+	data = xe_sriov_packet_alloc(xe);
+	if (!data)
+		return -ENOMEM;
+
+	ret = xe_sriov_packet_init(data, 0, 0, XE_SRIOV_PACKET_TYPE_DESCRIPTOR,
+				   0, MIGRATION_DESCRIPTOR_DWORDS * sizeof(u32));
+	if (ret) {
+		xe_sriov_packet_free(data);
+		return ret;
+	}
+
+	*desc = data;
+
+	return 0;
+}
+
+static void pf_pending_init(struct xe_device *xe, unsigned int vfid)
+{
+	struct xe_sriov_packet **data = pf_pick_pending(xe, vfid);
+
+	*data = NULL;
+}
+
+#define MIGRATION_TRAILER_SIZE 0
+static int pf_trailer_init(struct xe_device *xe, unsigned int vfid)
+{
+	struct xe_sriov_packet **trailer = pf_pick_trailer(xe, vfid);
+	struct xe_sriov_packet *data;
+	int ret;
+
+	data = xe_sriov_packet_alloc(xe);
+	if (!data)
+		return -ENOMEM;
+
+	ret = xe_sriov_packet_init(data, 0, 0, XE_SRIOV_PACKET_TYPE_TRAILER,
+				   0, MIGRATION_TRAILER_SIZE);
+	if (ret) {
+		xe_sriov_packet_free(data);
+		return ret;
+	}
+
+	*trailer = data;
+
+	return 0;
+}
+
+/**
+ * xe_sriov_packet_save_init() - Initialize the pending save migration packets.
+ * @xe: the &xe_device
+ * @vfid: the VF identifier
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int xe_sriov_packet_save_init(struct xe_device *xe, unsigned int vfid)
+{
+	int ret;
+
+	scoped_cond_guard(mutex_intr, return -EINTR, pf_migration_mutex(xe, vfid)) {
+		ret = pf_descriptor_init(xe, vfid);
+		if (ret)
+			return ret;
+
+		ret = pf_trailer_init(xe, vfid);
+		if (ret)
+			return ret;
+
+		pf_pending_init(xe, vfid);
+	}
+
+	return 0;
+}

drivers/gpu/drm/xe/xe_sriov_packet.h

@@ -19,4 +19,10 @@ int xe_sriov_packet_init(struct xe_sriov_packet *data, u8 tile_id, u8 gt_id,
 			 enum xe_sriov_packet_type, loff_t offset, size_t size);
 int xe_sriov_packet_init_from_hdr(struct xe_sriov_packet *data);
 
+ssize_t xe_sriov_packet_read_single(struct xe_device *xe, unsigned int vfid,
+				    char __user *buf, size_t len);
+ssize_t xe_sriov_packet_write_single(struct xe_device *xe, unsigned int vfid,
+				     const char __user *buf, size_t len);
+int xe_sriov_packet_save_init(struct xe_device *xe, unsigned int vfid);
+
 #endif

drivers/gpu/drm/xe/xe_sriov_pf_control.c

@@ -5,6 +5,7 @@
 
 #include "xe_device.h"
 #include "xe_gt_sriov_pf_control.h"
+#include "xe_sriov_packet.h"
 #include "xe_sriov_pf_control.h"
 #include "xe_sriov_printk.h"
 
@@ -165,6 +166,10 @@ int xe_sriov_pf_control_trigger_save_vf(struct xe_device *xe, unsigned int vfid)
 	unsigned int id;
 	int ret;
 
+	ret = xe_sriov_packet_save_init(xe, vfid);
+	if (ret)
+		return ret;
+
 	for_each_gt(gt, xe, id) {
 		ret = xe_gt_sriov_pf_control_trigger_save_vf(gt, vfid);
 		if (ret)

drivers/gpu/drm/xe/xe_sriov_pf_debugfs.c

@@ -13,6 +13,7 @@
 #include "xe_sriov_pf_control.h"
 #include "xe_sriov_pf_debugfs.h"
 #include "xe_sriov_pf_helpers.h"
+#include "xe_sriov_pf_migration.h"
 #include "xe_sriov_pf_provision.h"
 #include "xe_sriov_pf_service.h"
 #include "xe_sriov_printk.h"
@@ -162,6 +163,7 @@ static void pf_populate_pf(struct xe_device *xe, struct dentry *pfdent)
  *      /sys/kernel/debug/dri/BDF/
  *      ├── sriov
  *      │   ├── vf1
+ *      │   │   ├── migration_data
  *      │   │   ├── pause
  *      │   │   ├── reset
  *      │   │   ├── resume
@@ -250,6 +252,38 @@ DEFINE_VF_CONTROL_ATTRIBUTE(reset_vf);
 DEFINE_VF_CONTROL_ATTRIBUTE_RW(save_vf);
 DEFINE_VF_CONTROL_ATTRIBUTE_RW(restore_vf);
 
+static ssize_t data_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
+{
+	struct dentry *dent = file_dentry(file)->d_parent;
+	struct xe_device *xe = extract_xe(dent);
+	unsigned int vfid = extract_vfid(dent);
+
+	if (*pos)
+		return -ESPIPE;
+
+	return xe_sriov_pf_migration_write(xe, vfid, buf, count);
+}
+
+static ssize_t data_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct dentry *dent = file_dentry(file)->d_parent;
+	struct xe_device *xe = extract_xe(dent);
+	unsigned int vfid = extract_vfid(dent);
+
+	if (*ppos)
+		return -ESPIPE;
+
+	return xe_sriov_pf_migration_read(xe, vfid, buf, count);
+}
+
+static const struct file_operations data_vf_fops = {
+	.owner		= THIS_MODULE,
+	.open		= simple_open,
+	.write		= data_write,
+	.read		= data_read,
+	.llseek		= default_llseek,
+};
+
 static void pf_populate_vf(struct xe_device *xe, struct dentry *vfdent)
 {
 	debugfs_create_file("pause", 0200, vfdent, xe, &pause_vf_fops);
@@ -258,6 +292,7 @@ static void pf_populate_vf(struct xe_device *xe, struct dentry *vfdent)
 	debugfs_create_file("reset", 0200, vfdent, xe, &reset_vf_fops);
 	debugfs_create_file("save", 0600, vfdent, xe, &save_vf_fops);
 	debugfs_create_file("restore", 0600, vfdent, xe, &restore_vf_fops);
+	debugfs_create_file("migration_data", 0600, vfdent, xe, &data_vf_fops);
 }
 
 static void pf_populate_with_tiles(struct xe_device *xe, struct dentry *dent, unsigned int vfid)

drivers/gpu/drm/xe/xe_sriov_pf_migration.c

@@ -10,6 +10,7 @@
 #include "xe_gt_sriov_pf_migration.h"
 #include "xe_pm.h"
 #include "xe_sriov.h"
+#include "xe_sriov_packet.h"
 #include "xe_sriov_packet_types.h"
 #include "xe_sriov_pf_helpers.h"
 #include "xe_sriov_pf_migration.h"
@@ -54,6 +55,15 @@ static bool pf_check_migration_support(struct xe_device *xe)
 	return IS_ENABLED(CONFIG_DRM_XE_DEBUG);
 }
 
+static void pf_migration_cleanup(void *arg)
+{
+	struct xe_sriov_migration_state *migration = arg;
+
+	xe_sriov_packet_free(migration->pending);
+	xe_sriov_packet_free(migration->trailer);
+	xe_sriov_packet_free(migration->descriptor);
+}
+
 /**
  * xe_sriov_pf_migration_init() - Initialize support for SR-IOV VF migration.
  * @xe: the &xe_device
@@ -63,6 +73,7 @@ static bool pf_check_migration_support(struct xe_device *xe)
 int xe_sriov_pf_migration_init(struct xe_device *xe)
 {
 	unsigned int n, totalvfs;
+	int err;
 
 	xe_assert(xe, IS_SRIOV_PF(xe));
 
@@ -74,7 +85,15 @@ int xe_sriov_pf_migration_init(struct xe_device *xe)
 	for (n = 1; n <= totalvfs; n++) {
 		struct xe_sriov_migration_state *migration = pf_pick_migration(xe, n);
 
+		err = drmm_mutex_init(&xe->drm, &migration->lock);
+		if (err)
+			return err;
+
 		init_waitqueue_head(&migration->wq);
+
+		err = devm_add_action_or_reset(xe->drm.dev, pf_migration_cleanup, migration);
+		if (err)
+			return err;
 	}
 
 	return 0;
@@ -155,6 +174,36 @@ xe_sriov_pf_migration_save_consume(struct xe_device *xe, unsigned int vfid)
 	return data;
 }
 
+static int pf_handle_descriptor(struct xe_device *xe, unsigned int vfid,
+				struct xe_sriov_packet *data)
+{
+	if (data->hdr.tile_id != 0 || data->hdr.gt_id != 0)
+		return -EINVAL;
+
+	xe_sriov_packet_free(data);
+
+	return 0;
+}
+
+static int pf_handle_trailer(struct xe_device *xe, unsigned int vfid,
+			     struct xe_sriov_packet *data)
+{
+	struct xe_gt *gt;
+	u8 gt_id;
+
+	if (data->hdr.tile_id != 0 || data->hdr.gt_id != 0)
+		return -EINVAL;
+	if (data->hdr.offset != 0 || data->hdr.size != 0 || data->buff || data->bo)
+		return -EINVAL;
+
+	xe_sriov_packet_free(data);
+
+	for_each_gt(gt, xe, gt_id)
+		xe_gt_sriov_pf_control_restore_data_done(gt, vfid);
+
+	return 0;
+}
+
 /**
  * xe_sriov_pf_migration_restore_produce() - Produce a VF migration data packet to the device.
  * @xe: the &xe_device
@@ -174,6 +223,11 @@ int xe_sriov_pf_migration_restore_produce(struct xe_device *xe, unsigned int vfi
 
 	xe_assert(xe, IS_SRIOV_PF(xe));
 
+	if (data->hdr.type == XE_SRIOV_PACKET_TYPE_DESCRIPTOR)
+		return pf_handle_descriptor(xe, vfid, data);
+	if (data->hdr.type == XE_SRIOV_PACKET_TYPE_TRAILER)
+		return pf_handle_trailer(xe, vfid, data);
+
 	gt = xe_device_get_gt(xe, data->hdr.gt_id);
 	if (!gt || data->hdr.tile_id != gt->tile->id || data->hdr.type == 0) {
 		xe_sriov_err_ratelimited(xe, "Received invalid restore packet for VF%u (type:%u, tile:%u, GT:%u)\n",
@@ -183,3 +237,70 @@ int xe_sriov_pf_migration_restore_produce(struct xe_device *xe, unsigned int vfi
 
 	return xe_gt_sriov_pf_migration_restore_produce(gt, vfid, data);
 }
+
+/**
+ * xe_sriov_pf_migration_read() - Read migration data from the device.
+ * @xe: the &xe_device
+ * @vfid: the VF identifier
+ * @buf: start address of userspace buffer
+ * @len: requested read size from userspace
+ *
+ * Return: number of bytes that has been successfully read,
+ *	   0 if no more migration data is available,
+ *	   -errno on failure.
+ */
+ssize_t xe_sriov_pf_migration_read(struct xe_device *xe, unsigned int vfid,
+				   char __user *buf, size_t len)
+{
+	struct xe_sriov_migration_state *migration = pf_pick_migration(xe, vfid);
+	ssize_t ret, consumed = 0;
+
+	xe_assert(xe, IS_SRIOV_PF(xe));
+
+	scoped_cond_guard(mutex_intr, return -EINTR, &migration->lock) {
+		while (consumed < len) {
+			ret = xe_sriov_packet_read_single(xe, vfid, buf, len - consumed);
+			if (ret == -ENODATA)
+				break;
+			if (ret < 0)
+				return ret;
+
+			consumed += ret;
+			buf += ret;
+		}
+	}
+
+	return consumed;
+}
+
+/**
+ * xe_sriov_pf_migration_write() - Write migration data to the device.
+ * @xe: the &xe_device
+ * @vfid: the VF identifier
+ * @buf: start address of userspace buffer
+ * @len: requested write size from userspace
+ *
+ * Return: number of bytes that has been successfully written,
+ *	   -errno on failure.
+ */
+ssize_t xe_sriov_pf_migration_write(struct xe_device *xe, unsigned int vfid,
+				    const char __user *buf, size_t len)
+{
+	struct xe_sriov_migration_state *migration = pf_pick_migration(xe, vfid);
+	ssize_t ret, produced = 0;
+
+	xe_assert(xe, IS_SRIOV_PF(xe));
+
+	scoped_cond_guard(mutex_intr, return -EINTR, &migration->lock) {
+		while (produced < len) {
+			ret = xe_sriov_packet_write_single(xe, vfid, buf, len - produced);
+			if (ret < 0)
+				return ret;
+
+			produced += ret;
+			buf += ret;
+		}
+	}
+
+	return produced;
+}

drivers/gpu/drm/xe/xe_sriov_pf_migration.h

@@ -20,4 +20,9 @@ struct xe_sriov_packet *
 xe_sriov_pf_migration_save_consume(struct xe_device *xe, unsigned int vfid);
 wait_queue_head_t *xe_sriov_pf_migration_waitqueue(struct xe_device *xe, unsigned int vfid);
 
+ssize_t xe_sriov_pf_migration_read(struct xe_device *xe, unsigned int vfid,
+				   char __user *buf, size_t len);
+ssize_t xe_sriov_pf_migration_write(struct xe_device *xe, unsigned int vfid,
+				    const char __user *buf, size_t len);
+
 #endif

drivers/gpu/drm/xe/xe_sriov_pf_migration_types.h

@@ -7,6 +7,7 @@
 #define _XE_SRIOV_PF_MIGRATION_TYPES_H_
 
 #include <linux/types.h>
+#include <linux/mutex_types.h>
 #include <linux/wait.h>
 
 /**
@@ -23,6 +24,14 @@ struct xe_sriov_pf_migration {
 struct xe_sriov_migration_state {
 	/** @wq: waitqueue used to avoid busy-waiting for snapshot production/consumption */
 	wait_queue_head_t wq;
+	/** @lock: Mutex protecting the migration data */
+	struct mutex lock;
+	/** @pending: currently processed data packet of VF resource */
+	struct xe_sriov_packet *pending;
+	/** @trailer: data packet used to indicate the end of stream */
+	struct xe_sriov_packet *trailer;
+	/** @descriptor: data packet containing the metadata describing the device */
+	struct xe_sriov_packet *descriptor;
 };
 
 #endif