Re: [RFC PATCH 3/5] nvme-vfio: enable the function of VFIO live migration.

From: Max Gurtovoy
Date: Thu Jan 19 2023 - 05:21:32 EST


Hi Leo,

On 06/12/2022 7:58, Lei Rao wrote:
Implement specific VFIO live migration operations for NVMe devices.

Signed-off-by: Lei Rao <lei.rao@xxxxxxxxx>
Signed-off-by: Yadong Li <yadong.li@xxxxxxxxx>
Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Reviewed-by: Eddie Dong <eddie.dong@xxxxxxxxx>
Reviewed-by: Hang Yuan <hang.yuan@xxxxxxxxx>
---
drivers/vfio/pci/nvme/Kconfig |   5 +-
drivers/vfio/pci/nvme/nvme.c  | 543 ++++++++++++++++++++++++++++++++--
drivers/vfio/pci/nvme/nvme.h  | 111 +++++++
3 files changed, 637 insertions(+), 22 deletions(-)
create mode 100644 drivers/vfio/pci/nvme/nvme.h

diff --git a/drivers/vfio/pci/nvme/Kconfig b/drivers/vfio/pci/nvme/Kconfig
index c281fe154007..12e0eaba0de1 100644
--- a/drivers/vfio/pci/nvme/Kconfig
+++ b/drivers/vfio/pci/nvme/Kconfig
@@ -1,9 +1,10 @@
# SPDX-License-Identifier: GPL-2.0-only
config NVME_VFIO_PCI
    tristate "VFIO support for NVMe PCI devices"
+    depends on NVME_CORE
    depends on VFIO_PCI_CORE
    help
-      This provides generic VFIO PCI support for NVMe device
-      using the VFIO framework.
+      This provides migration support for NVMe devices using the
+      VFIO framework.

      If you don't know what to do here, say N.
diff --git a/drivers/vfio/pci/nvme/nvme.c b/drivers/vfio/pci/nvme/nvme.c
index f1386d8a9287..698e470a4e53 100644
--- a/drivers/vfio/pci/nvme/nvme.c
+++ b/drivers/vfio/pci/nvme/nvme.c
@@ -13,29 +13,503 @@
#include <linux/types.h>
#include <linux/vfio.h>
#include <linux/anon_inodes.h>
-#include <linux/kernel.h>
-#include <linux/vfio_pci_core.h>
+
+#include "nvme.h"
+
+#define MAX_MIGRATION_SIZE (256 * 1024)
+
+static int nvmevf_cmd_suspend_device(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+    struct pci_dev *dev = nvmevf_dev->core_device.pdev;
+    struct nvme_live_mig_command c = { };
+    int ret;
+
+    c.suspend.opcode = nvme_admin_live_mig_suspend;
+    c.suspend.vf_index = nvmevf_dev->vf_id;
+
+    ret = nvme_submit_vf_cmd(dev, (struct nvme_command *)&c, NULL, NULL, 0);
+    if (ret) {
+        dev_warn(&dev->dev, "Suspend virtual function failed (ret=0x%x)\n", ret);
+        return ret;
+    }
+    return 0;
+}
+
+static int nvmevf_cmd_resume_device(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+    struct pci_dev *dev = nvmevf_dev->core_device.pdev;
+    struct nvme_live_mig_command c = { };
+    int ret;
+
+    c.resume.opcode = nvme_admin_live_mig_resume;
+    c.resume.vf_index = nvmevf_dev->vf_id;
+
+    ret = nvme_submit_vf_cmd(dev, (struct nvme_command *)&c, NULL, NULL, 0);
+    if (ret) {
+        dev_warn(&dev->dev, "Resume virtual function failed (ret=0x%x)\n", ret);
+        return ret;
+    }
+    return 0;
+}
+
+static int nvmevf_cmd_query_data_size(struct nvmevf_pci_core_device *nvmevf_dev,
+                      size_t *state_size)
+{
+    struct pci_dev *dev = nvmevf_dev->core_device.pdev;
+    struct nvme_live_mig_command c = { };
+    size_t result;
+    int ret;
+
+    c.query.opcode = nvme_admin_live_mig_query_data_size;
+    c.query.vf_index = nvmevf_dev->vf_id;
+
+    ret = nvme_submit_vf_cmd(dev, (struct nvme_command *)&c, &result, NULL, 0);
+    if (ret) {
+        dev_warn(&dev->dev, "Query the states size failed (ret=0x%x)\n", ret);
+        *state_size = 0;
+        return ret;
+    }
+    *state_size = result;
+    return 0;
+}
+
+static int nvmevf_cmd_save_data(struct nvmevf_pci_core_device *nvmevf_dev,
+                    void *buffer, size_t buffer_len)
+{
+    struct pci_dev *dev = nvmevf_dev->core_device.pdev;
+    struct nvme_live_mig_command c = { };
+    int ret;
+
+    c.save.opcode = nvme_admin_live_mig_save_data;
+    c.save.vf_index = nvmevf_dev->vf_id;
+
+    ret = nvme_submit_vf_cmd(dev, (struct nvme_command *)&c, NULL, buffer, buffer_len);
+    if (ret) {
+        dev_warn(&dev->dev, "Save the device states failed (ret=0x%x)\n", ret);
+        return ret;
+    }
+    return 0;
+}
+
+static int nvmevf_cmd_load_data(struct nvmevf_pci_core_device *nvmevf_dev,
+                    struct nvmevf_migration_file *migf)
+{
+    struct pci_dev *dev = nvmevf_dev->core_device.pdev;
+    struct nvme_live_mig_command c = { };
+    int ret;
+
+    c.load.opcode = nvme_admin_live_mig_load_data;
+    c.load.vf_index = nvmevf_dev->vf_id;
+    c.load.size = migf->total_length;
+
+    ret = nvme_submit_vf_cmd(dev, (struct nvme_command *)&c, NULL,
+            migf->vf_data, migf->total_length);
+    if (ret) {
+        dev_warn(&dev->dev, "Load the device states failed (ret=0x%x)\n", ret);
+        return ret;
+    }
+    return 0;
+}
+
+static struct nvmevf_pci_core_device *nvmevf_drvdata(struct pci_dev *pdev)
+{
+    struct vfio_pci_core_device *core_device = dev_get_drvdata(&pdev->dev);
+
+    return container_of(core_device, struct nvmevf_pci_core_device, core_device);
+}
+
+static void nvmevf_disable_fd(struct nvmevf_migration_file *migf)
+{
+    mutex_lock(&migf->lock);
+
+    /* release the device states buffer */
+    kvfree(migf->vf_data);
+    migf->vf_data = NULL;
+    migf->disabled = true;
+    migf->total_length = 0;
+    migf->filp->f_pos = 0;
+    mutex_unlock(&migf->lock);
+}
+
+static int nvmevf_release_file(struct inode *inode, struct file *filp)
+{
+    struct nvmevf_migration_file *migf = filp->private_data;
+
+    nvmevf_disable_fd(migf);
+    mutex_destroy(&migf->lock);
+    kfree(migf);
+    return 0;
+}
+
+static ssize_t nvmevf_save_read(struct file *filp, char __user *buf, size_t len, loff_t *pos)
+{
+    struct nvmevf_migration_file *migf = filp->private_data;
+    ssize_t done = 0;
+    int ret;
+
+    if (pos)
+        return -ESPIPE;
+    pos = &filp->f_pos;
+
+    mutex_lock(&migf->lock);
+    if (*pos > migf->total_length) {
+        done = -EINVAL;
+        goto out_unlock;
+    }
+
+    if (migf->disabled) {
+        done = -EINVAL;
+        goto out_unlock;
+    }
+
+    len = min_t(size_t, migf->total_length - *pos, len);
+    if (len) {
+        ret = copy_to_user(buf, migf->vf_data + *pos, len);
+        if (ret) {
+            done = -EFAULT;
+            goto out_unlock;
+        }
+        *pos += len;
+        done = len;
+    }
+
+out_unlock:
+    mutex_unlock(&migf->lock);
+    return done;
+}
+
+static const struct file_operations nvmevf_save_fops = {
+    .owner = THIS_MODULE,
+    .read = nvmevf_save_read,
+    .release = nvmevf_release_file,
+    .llseek = no_llseek,
+};
+
+static ssize_t nvmevf_resume_write(struct file *filp, const char __user *buf,
+                       size_t len, loff_t *pos)
+{
+    struct nvmevf_migration_file *migf = filp->private_data;
+    loff_t requested_length;
+    ssize_t done = 0;
+    int ret;
+
+    if (pos)
+        return -ESPIPE;
+    pos = &filp->f_pos;
+
+    if (*pos < 0 || check_add_overflow((loff_t)len, *pos, &requested_length))
+        return -EINVAL;
+
+    if (requested_length > MAX_MIGRATION_SIZE)
+        return -ENOMEM;
+    mutex_lock(&migf->lock);
+    if (migf->disabled) {
+        done = -ENODEV;
+        goto out_unlock;
+    }
+
+    ret = copy_from_user(migf->vf_data + *pos, buf, len);
+    if (ret) {
+        done = -EFAULT;
+        goto out_unlock;
+    }
+    *pos += len;
+    done = len;
+    migf->total_length += len;
+
+out_unlock:
+    mutex_unlock(&migf->lock);
+    return done;
+}
+
+static const struct file_operations nvmevf_resume_fops = {
+    .owner = THIS_MODULE,
+    .write = nvmevf_resume_write,
+    .release = nvmevf_release_file,
+    .llseek = no_llseek,
+};
+
+static void nvmevf_disable_fds(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+    if (nvmevf_dev->resuming_migf) {
+        nvmevf_disable_fd(nvmevf_dev->resuming_migf);
+        fput(nvmevf_dev->resuming_migf->filp);
+        nvmevf_dev->resuming_migf = NULL;
+    }
+
+    if (nvmevf_dev->saving_migf) {
+        nvmevf_disable_fd(nvmevf_dev->saving_migf);
+        fput(nvmevf_dev->saving_migf->filp);
+        nvmevf_dev->saving_migf = NULL;
+    }
+}
+
+static struct nvmevf_migration_file *
+nvmevf_pci_resume_device_data(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+    struct nvmevf_migration_file *migf;
+    int ret;
+
+    migf = kzalloc(sizeof(*migf), GFP_KERNEL);
+    if (!migf)
+        return ERR_PTR(-ENOMEM);
+
+    migf->filp = anon_inode_getfile("nvmevf_mig", &nvmevf_resume_fops, migf,
+                    O_WRONLY);
+    if (IS_ERR(migf->filp)) {
+        int err = PTR_ERR(migf->filp);
+
+        kfree(migf);
+        return ERR_PTR(err);
+    }
+    stream_open(migf->filp->f_inode, migf->filp);
+    mutex_init(&migf->lock);
+
+    /* Allocate buffer to load the device states and the max states is 256K */
+    migf->vf_data = kvzalloc(MAX_MIGRATION_SIZE, GFP_KERNEL);
+    if (!migf->vf_data) {
+        ret = -ENOMEM;
+        goto out_free;
+    }
+
+    return migf;
+
+out_free:
+    fput(migf->filp);
+    return ERR_PTR(ret);
+}
+
+static struct nvmevf_migration_file *
+nvmevf_pci_save_device_data(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+    struct nvmevf_migration_file *migf;
+    int ret;
+
+    migf = kzalloc(sizeof(*migf), GFP_KERNEL);
+    if (!migf)
+        return ERR_PTR(-ENOMEM);
+
+    migf->filp = anon_inode_getfile("nvmevf_mig", &nvmevf_save_fops, migf,
+                    O_RDONLY);
+    if (IS_ERR(migf->filp)) {
+        int err = PTR_ERR(migf->filp);
+
+        kfree(migf);
+        return ERR_PTR(err);
+    }
+
+    stream_open(migf->filp->f_inode, migf->filp);
+    mutex_init(&migf->lock);
+
+    ret = nvmevf_cmd_query_data_size(nvmevf_dev, &migf->total_length);
+    if (ret)
+        goto out_free;
+    /* Allocate buffer and save the device states*/
+    migf->vf_data = kvzalloc(migf->total_length, GFP_KERNEL);
+    if (!migf->vf_data) {
+        ret = -ENOMEM;
+        goto out_free;
+    }
+
+    ret = nvmevf_cmd_save_data(nvmevf_dev, migf->vf_data, migf->total_length);
+    if (ret)
+        goto out_free;
+
+    return migf;
+out_free:
+    fput(migf->filp);
+    return ERR_PTR(ret);
+}
+
+static struct file *
+nvmevf_pci_step_device_state_locked(struct nvmevf_pci_core_device *nvmevf_dev, u32 new)
+{
+    u32 cur = nvmevf_dev->mig_state;
+    int ret;
+
+    if (cur == VFIO_DEVICE_STATE_RUNNING && new == VFIO_DEVICE_STATE_STOP) {
+        ret = nvmevf_cmd_suspend_device(nvmevf_dev);
+        if (ret)
+            return ERR_PTR(ret);
+        return NULL;
+    }
+
+    if (cur == VFIO_DEVICE_STATE_STOP && new == VFIO_DEVICE_STATE_STOP_COPY) {
+        struct nvmevf_migration_file *migf;
+
+        migf = nvmevf_pci_save_device_data(nvmevf_dev);
+        if (IS_ERR(migf))
+            return ERR_CAST(migf);
+        get_file(migf->filp);
+        nvmevf_dev->saving_migf = migf;
+        return migf->filp;
+    }
+
+    if (cur == VFIO_DEVICE_STATE_STOP_COPY && new == VFIO_DEVICE_STATE_STOP) {
+        nvmevf_disable_fds(nvmevf_dev);
+        return NULL;
+    }
+
+    if (cur == VFIO_DEVICE_STATE_STOP && new == VFIO_DEVICE_STATE_RESUMING) {
+        struct nvmevf_migration_file *migf;
+
+        migf = nvmevf_pci_resume_device_data(nvmevf_dev);
+        if (IS_ERR(migf))
+            return ERR_CAST(migf);
+        get_file(migf->filp);
+        nvmevf_dev->resuming_migf = migf;
+        return migf->filp;
+    }
+
+    if (cur == VFIO_DEVICE_STATE_RESUMING && new == VFIO_DEVICE_STATE_STOP) {
+        ret = nvmevf_cmd_load_data(nvmevf_dev, nvmevf_dev->resuming_migf);
+        if (ret)
+            return ERR_PTR(ret);
+        nvmevf_disable_fds(nvmevf_dev);
+        return NULL;
+    }
+
+    if (cur == VFIO_DEVICE_STATE_STOP && new == VFIO_DEVICE_STATE_RUNNING) {
+        nvmevf_cmd_resume_device(nvmevf_dev);
+        return NULL;
+    }
+
+    /* vfio_mig_get_next_state() does not use arcs other than the above */
+    WARN_ON(true);
+    return ERR_PTR(-EINVAL);
+}
+
+static void nvmevf_state_mutex_unlock(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+again:
+    spin_lock(&nvmevf_dev->reset_lock);
+    if (nvmevf_dev->deferred_reset) {
+        nvmevf_dev->deferred_reset = false;
+        spin_unlock(&nvmevf_dev->reset_lock);
+        nvmevf_dev->mig_state = VFIO_DEVICE_STATE_RUNNING;
+        nvmevf_disable_fds(nvmevf_dev);
+        goto again;
+    }
+    mutex_unlock(&nvmevf_dev->state_mutex);
+    spin_unlock(&nvmevf_dev->reset_lock);
+}
+
+static struct file *
+nvmevf_pci_set_device_state(struct vfio_device *vdev, enum vfio_device_mig_state new_state)
+{
+    struct nvmevf_pci_core_device *nvmevf_dev = container_of(vdev,
+            struct nvmevf_pci_core_device, core_device.vdev);
+    enum vfio_device_mig_state next_state;
+    struct file *res = NULL;
+    int ret;
+
+    mutex_lock(&nvmevf_dev->state_mutex);
+    while (new_state != nvmevf_dev->mig_state) {
+        ret = vfio_mig_get_next_state(vdev, nvmevf_dev->mig_state, new_state, &next_state);
+        if (ret) {
+            res = ERR_PTR(-EINVAL);
+            break;
+        }
+
+        res = nvmevf_pci_step_device_state_locked(nvmevf_dev, next_state);
+        if (IS_ERR(res))
+            break;
+        nvmevf_dev->mig_state = next_state;
+        if (WARN_ON(res && new_state != nvmevf_dev->mig_state)) {
+            fput(res);
+            res = ERR_PTR(-EINVAL);
+            break;
+        }
+    }
+    nvmevf_state_mutex_unlock(nvmevf_dev);
+    return res;
+}
+
+static int nvmevf_pci_get_device_state(struct vfio_device *vdev,
+                       enum vfio_device_mig_state *curr_state)
+{
+    struct nvmevf_pci_core_device *nvmevf_dev = container_of(
+            vdev, struct nvmevf_pci_core_device, core_device.vdev);
+
+    mutex_lock(&nvmevf_dev->state_mutex);
+    *curr_state = nvmevf_dev->mig_state;
+    nvmevf_state_mutex_unlock(nvmevf_dev);
+    return 0;
+}

static int nvmevf_pci_open_device(struct vfio_device *core_vdev)
{
-    struct vfio_pci_core_device *vdev =
-        container_of(core_vdev, struct vfio_pci_core_device, vdev);
+    struct nvmevf_pci_core_device *nvmevf_dev = container_of(
+            core_vdev, struct nvmevf_pci_core_device, core_device.vdev);
+    struct vfio_pci_core_device *vdev = &nvmevf_dev->core_device;
    int ret;

    ret = vfio_pci_core_enable(vdev);
    if (ret)
        return ret;

+    if (nvmevf_dev->migrate_cap)
+        nvmevf_dev->mig_state = VFIO_DEVICE_STATE_RUNNING;
    vfio_pci_core_finish_enable(vdev);
    return 0;
}

+static void nvmevf_cmd_close_migratable(struct nvmevf_pci_core_device *nvmevf_dev)
+{
+    if (!nvmevf_dev->migrate_cap)
+        return;
+
+    mutex_lock(&nvmevf_dev->state_mutex);
+    nvmevf_disable_fds(nvmevf_dev);
+    nvmevf_state_mutex_unlock(nvmevf_dev);
+}
+
+static void nvmevf_pci_close_device(struct vfio_device *core_vdev)
+{
+    struct nvmevf_pci_core_device *nvmevf_dev = container_of(
+            core_vdev, struct nvmevf_pci_core_device, core_device.vdev);
+
+    nvmevf_cmd_close_migratable(nvmevf_dev);
+    vfio_pci_core_close_device(core_vdev);
+}
+
+static const struct vfio_migration_ops nvmevf_pci_mig_ops = {
+    .migration_set_state = nvmevf_pci_set_device_state,
+    .migration_get_state = nvmevf_pci_get_device_state,
+};
+
+static int nvmevf_migration_init_dev(struct vfio_device *core_vdev)
+{
+    struct nvmevf_pci_core_device *nvmevf_dev = container_of(core_vdev,
+                    struct nvmevf_pci_core_device, core_device.vdev);
+    struct pci_dev *pdev = to_pci_dev(core_vdev->dev);
+    int vf_id;
+    int ret = -1;
+
+    if (!pdev->is_virtfn)
+        return ret;
+
+    nvmevf_dev->migrate_cap = 1;
+
+    vf_id = pci_iov_vf_id(pdev);
+    if (vf_id < 0)
+        return ret;
+    nvmevf_dev->vf_id = vf_id + 1;
+    core_vdev->migration_flags = VFIO_MIGRATION_STOP_COPY;
+
+    mutex_init(&nvmevf_dev->state_mutex);
+    spin_lock_init(&nvmevf_dev->reset_lock);
+    core_vdev->mig_ops = &nvmevf_pci_mig_ops;
+
+    return vfio_pci_core_init_dev(core_vdev);
+}
+
static const struct vfio_device_ops nvmevf_pci_ops = {
    .name = "nvme-vfio-pci",
-    .init = vfio_pci_core_init_dev,
+    .init = nvmevf_migration_init_dev,
    .release = vfio_pci_core_release_dev,
    .open_device = nvmevf_pci_open_device,
-    .close_device = vfio_pci_core_close_device,
+    .close_device = nvmevf_pci_close_device,
    .ioctl = vfio_pci_core_ioctl,
    .device_feature = vfio_pci_core_ioctl_feature,
    .read = vfio_pci_core_read,
@@ -47,32 +521,56 @@ static const struct vfio_device_ops nvmevf_pci_ops = {

static int nvmevf_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
-    struct vfio_pci_core_device *vdev;
+    struct nvmevf_pci_core_device *nvmevf_dev;
    int ret;

-    vdev = vfio_alloc_device(vfio_pci_core_device, vdev, &pdev->dev,
-                &nvmevf_pci_ops);
-    if (IS_ERR(vdev))
-        return PTR_ERR(vdev);
+    nvmevf_dev = vfio_alloc_device(nvmevf_pci_core_device, core_device.vdev,
+                    &pdev->dev, &nvmevf_pci_ops);
+    if (IS_ERR(nvmevf_dev))
+        return PTR_ERR(nvmevf_dev);

-    dev_set_drvdata(&pdev->dev, vdev);
-    ret = vfio_pci_core_register_device(vdev);
+    dev_set_drvdata(&pdev->dev, &nvmevf_dev->core_device);
+    ret = vfio_pci_core_register_device(&nvmevf_dev->core_device);
    if (ret)
        goto out_put_dev;
-
    return 0;

out_put_dev:
-    vfio_put_device(&vdev->vdev);
+    vfio_put_device(&nvmevf_dev->core_device.vdev);
    return ret;
+
}

static void nvmevf_pci_remove(struct pci_dev *pdev)
{
-    struct vfio_pci_core_device *vdev = dev_get_drvdata(&pdev->dev);
+    struct nvmevf_pci_core_device *nvmevf_dev = nvmevf_drvdata(pdev);
+
+ vfio_pci_core_unregister_device(&nvmevf_dev->core_device);
+    vfio_put_device(&nvmevf_dev->core_device.vdev);
+}
+
+static void nvmevf_pci_aer_reset_done(struct pci_dev *pdev)
+{
+    struct nvmevf_pci_core_device *nvmevf_dev = nvmevf_drvdata(pdev);
+
+    if (!nvmevf_dev->migrate_cap)
+        return;

-    vfio_pci_core_unregister_device(vdev);
-    vfio_put_device(&vdev->vdev);
+    /*
+     * As the higher VFIO layers are holding locks across reset and using
+     * those same locks with the mm_lock we need to prevent ABBA deadlock
+     * with the state_mutex and mm_lock.
+     * In case the state_mutex was taken already we defer the cleanup work
+     * to the unlock flow of the other running context.
+     */
+    spin_lock(&nvmevf_dev->reset_lock);
+    nvmevf_dev->deferred_reset = true;
+    if (!mutex_trylock(&nvmevf_dev->state_mutex)) {
+        spin_unlock(&nvmevf_dev->reset_lock);
+        return;
+    }
+    spin_unlock(&nvmevf_dev->reset_lock);
+    nvmevf_state_mutex_unlock(nvmevf_dev);
}

static const struct pci_device_id nvmevf_pci_table[] = {
@@ -83,12 +581,17 @@ static const struct pci_device_id nvmevf_pci_table[] = {

MODULE_DEVICE_TABLE(pci, nvmevf_pci_table);

+static const struct pci_error_handlers nvmevf_err_handlers = {
+    .reset_done = nvmevf_pci_aer_reset_done,
+    .error_detected = vfio_pci_core_aer_err_detected,
+};
+
static struct pci_driver nvmevf_pci_driver = {
    .name = KBUILD_MODNAME,
    .id_table = nvmevf_pci_table,
    .probe = nvmevf_pci_probe,
    .remove = nvmevf_pci_remove,
-    .err_handler = &vfio_pci_core_err_handlers,
+    .err_handler = &nvmevf_err_handlers,
    .driver_managed_dma = true,
};

@@ -96,4 +599,4 @@ module_pci_driver(nvmevf_pci_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Lei Rao <lei.rao@xxxxxxxxx>");
-MODULE_DESCRIPTION("NVMe VFIO PCI - Generic VFIO PCI driver for NVMe");
+MODULE_DESCRIPTION("NVMe VFIO PCI - VFIO PCI driver with live migration support for NVMe");
diff --git a/drivers/vfio/pci/nvme/nvme.h b/drivers/vfio/pci/nvme/nvme.h
new file mode 100644
index 000000000000..c8464554ef53
--- /dev/null
+++ b/drivers/vfio/pci/nvme/nvme.h
@@ -0,0 +1,111 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2022, INTEL CORPORATION. All rights reserved
+ */
+
+#ifndef NVME_VFIO_PCI_H
+#define NVME_VFIO_PCI_H
+
+#include <linux/kernel.h>
+#include <linux/vfio_pci_core.h>
+#include <linux/nvme.h>
+
+struct nvme_live_mig_query_size {
+    __u8    opcode;
+    __u8    flags;
+    __u16    command_id;
+    __u32    rsvd1[9];
+    __u16    vf_index;
+    __u16    rsvd2;
+    __u32    rsvd3[5];
+};
+
+struct nvme_live_mig_suspend {
+    __u8    opcode;
+    __u8    flags;
+    __u16    command_id;
+    __u32    rsvd1[9];
+    __u16    vf_index;
+    __u16    rsvd2;
+    __u32    rsvd3[5];
+};
+
+struct nvme_live_mig_resume {
+    __u8    opcode;
+    __u8    flags;
+    __u16   command_id;
+    __u32   rsvd1[9];
+    __u16   vf_index;
+    __u16   rsvd2;
+    __u32   rsvd3[5];
+};
+
+struct nvme_live_mig_save_data {
+    __u8    opcode;
+    __u8    flags;
+    __u16    command_id;
+    __u32    rsvd1[5];
+    __le64    prp1;
+    __le64    prp2;
+    __u16    vf_index;
+    __u16    rsvd2;
+    __u32    rsvd3[5];
+};

Just noticed that the save_data (similar to READ operation) doesn't have size/length member.
How does it work for you ?

BTW,

Are you doing iterative reads from the device to get the state ?

+
+struct nvme_live_mig_load_data {
+    __u8    opcode;
+    __u8    flags;
+    __u16   command_id;
+    __u32   rsvd1[5];
+    __le64  prp1;
+    __le64  prp2;
+    __u16   vf_index;
+    __u16    rsvd2;
+    __u32    size;
+    __u32   rsvd3[4];
+};
+
+enum nvme_live_mig_admin_opcode {
+    nvme_admin_live_mig_query_data_size    = 0xC4,
+    nvme_admin_live_mig_suspend        = 0xC8,
+    nvme_admin_live_mig_resume        = 0xCC,
+    nvme_admin_live_mig_save_data        = 0xD2,
+    nvme_admin_live_mig_load_data        = 0xD5,
+};
+
+struct nvme_live_mig_command {
+    union {
+        struct nvme_live_mig_query_size query;
+        struct nvme_live_mig_suspend    suspend;
+        struct nvme_live_mig_resume    resume;
+        struct nvme_live_mig_save_data    save;
+        struct nvme_live_mig_load_data    load;
+    };
+};
+
+struct nvmevf_migration_file {
+    struct file *filp;
+    struct mutex lock;
+    bool disabled;
+    u8 *vf_data;
+    size_t total_length;
+};
+
+struct nvmevf_pci_core_device {
+    struct vfio_pci_core_device core_device;
+    int vf_id;
+    u8 migrate_cap:1;
+    u8 deferred_reset:1;
+    /* protect migration state */
+    struct mutex state_mutex;
+    enum vfio_device_mig_state mig_state;
+    /* protect the reset_done flow */
+    spinlock_t reset_lock;
+    struct nvmevf_migration_file *resuming_migf;
+    struct nvmevf_migration_file *saving_migf;
+};
+
+extern int nvme_submit_vf_cmd(struct pci_dev *dev, struct nvme_command *cmd,
+            size_t *result, void *buffer, unsigned int bufflen);
+
+#endif /* NVME_VFIO_PCI_H */