Message-ID: <20211015134820.603c45d0.alex.williamson@redhat.com>
Date:   Fri, 15 Oct 2021 13:48:20 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Yishai Hadas <yishaih@...dia.com>
Cc:     <bhelgaas@...gle.com>, <jgg@...dia.com>, <saeedm@...dia.com>,
        <linux-pci@...r.kernel.org>, <kvm@...r.kernel.org>,
        <netdev@...r.kernel.org>, <kuba@...nel.org>, <leonro@...dia.com>,
        <kwankhede@...dia.com>, <mgurtovoy@...dia.com>, <maorg@...dia.com>
Subject: Re: [PATCH V1 mlx5-next 11/13] vfio/mlx5: Implement vfio_pci driver
 for mlx5 devices

On Wed, 13 Oct 2021 12:47:05 +0300
Yishai Hadas <yishaih@...dia.com> wrote:

> This patch adds support for vfio_pci driver for mlx5 devices.
> 
> It uses vfio_pci_core to register to the VFIO subsystem and then
> implements the mlx5 specific logic in the migration area.
> 
> The migration implementation follows the definition from uapi/vfio.h and
> uses the mlx5 VF->PF command channel to achieve it.
> 
> This patch implements the suspend/resume flows.
> 
> Signed-off-by: Yishai Hadas <yishaih@...dia.com>
> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
> ---
>  MAINTAINERS                    |   6 +
>  drivers/vfio/pci/Kconfig       |   3 +
>  drivers/vfio/pci/Makefile      |   2 +
>  drivers/vfio/pci/mlx5/Kconfig  |  11 +
>  drivers/vfio/pci/mlx5/Makefile |   4 +
>  drivers/vfio/pci/mlx5/main.c   | 692 +++++++++++++++++++++++++++++++++
>  6 files changed, 718 insertions(+)
>  create mode 100644 drivers/vfio/pci/mlx5/Kconfig
>  create mode 100644 drivers/vfio/pci/mlx5/Makefile
>  create mode 100644 drivers/vfio/pci/mlx5/main.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index abdcbcfef73d..e824bfab4a01 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -19699,6 +19699,12 @@ L:	kvm@...r.kernel.org
>  S:	Maintained
>  F:	drivers/vfio/platform/
>  
> +VFIO MLX5 PCI DRIVER
> +M:	Yishai Hadas <yishaih@...dia.com>
> +L:	kvm@...r.kernel.org
> +S:	Maintained
> +F:	drivers/vfio/pci/mlx5/
> +
>  VGA_SWITCHEROO
>  R:	Lukas Wunner <lukas@...ner.de>
>  S:	Maintained
> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> index 860424ccda1b..187b9c259944 100644
> --- a/drivers/vfio/pci/Kconfig
> +++ b/drivers/vfio/pci/Kconfig
> @@ -43,4 +43,7 @@ config VFIO_PCI_IGD
>  
>  	  To enable Intel IGD assignment through vfio-pci, say Y.
>  endif
> +
> +source "drivers/vfio/pci/mlx5/Kconfig"
> +
>  endif
> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> index 349d68d242b4..ed9d6f2e0555 100644
> --- a/drivers/vfio/pci/Makefile
> +++ b/drivers/vfio/pci/Makefile
> @@ -7,3 +7,5 @@ obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o
>  vfio-pci-y := vfio_pci.o
>  vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
>  obj-$(CONFIG_VFIO_PCI) += vfio-pci.o
> +
> +obj-$(CONFIG_MLX5_VFIO_PCI)           += mlx5/
> diff --git a/drivers/vfio/pci/mlx5/Kconfig b/drivers/vfio/pci/mlx5/Kconfig
> new file mode 100644
> index 000000000000..a3ce00add4fe
> --- /dev/null
> +++ b/drivers/vfio/pci/mlx5/Kconfig
> @@ -0,0 +1,11 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config MLX5_VFIO_PCI
> +	tristate "VFIO support for MLX5 PCI devices"
> +	depends on MLX5_CORE
> +	select VFIO_PCI_CORE
> +	help
> +	  This provides a PCI support for MLX5 devices using the VFIO
> +	  framework. The device specific driver supports suspend/resume
> +	  of the MLX5 device.


Why are we doing everything except describing this as migration
support?  First sentence also needs some grammar help.


> +
> +	  If you don't know what to do here, say N.
> diff --git a/drivers/vfio/pci/mlx5/Makefile b/drivers/vfio/pci/mlx5/Makefile
> new file mode 100644
> index 000000000000..689627da7ff5
> --- /dev/null
> +++ b/drivers/vfio/pci/mlx5/Makefile
> @@ -0,0 +1,4 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_MLX5_VFIO_PCI) += mlx5-vfio-pci.o
> +mlx5-vfio-pci-y := main.o cmd.o
> +
> diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
> new file mode 100644
> index 000000000000..e36302b444a6
> --- /dev/null
> +++ b/drivers/vfio/pci/mlx5/main.c
> @@ -0,0 +1,692 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved
> + */
> +
> +#include <linux/device.h>
> +#include <linux/eventfd.h>
> +#include <linux/file.h>
> +#include <linux/interrupt.h>
> +#include <linux/iommu.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/notifier.h>
> +#include <linux/pci.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/types.h>
> +#include <linux/uaccess.h>
> +#include <linux/vfio.h>
> +#include <linux/sched/mm.h>
> +#include <linux/vfio_pci_core.h>
> +
> +#include "cmd.h"
> +
> +enum {
> +	MLX5VF_PCI_FREEZED = 1 << 0,
> +};
> +
> +enum {
> +	MLX5VF_REGION_PENDING_BYTES = 1 << 0,
> +	MLX5VF_REGION_DATA_SIZE = 1 << 1,
> +};
> +
> +#define MLX5VF_MIG_REGION_DATA_SIZE SZ_128K
> +/* Data section offset from migration region */
> +#define MLX5VF_MIG_REGION_DATA_OFFSET                                          \
> +	(sizeof(struct vfio_device_migration_info))
> +
> +#define VFIO_DEVICE_MIGRATION_OFFSET(x)                                        \
> +	(offsetof(struct vfio_device_migration_info, x))
> +
> +struct mlx5vf_pci_migration_info {
> +	u32 vfio_dev_state; /* VFIO_DEVICE_STATE_XXX */
> +	u32 dev_state; /* device migration state */
> +	u32 region_state; /* Use MLX5VF_REGION_XXX */
> +	u16 vhca_id;
> +	struct mlx5_vhca_state_data vhca_state_data;
> +};
> +
> +struct mlx5vf_pci_core_device {
> +	struct vfio_pci_core_device core_device;
> +	u8 migrate_cap:1;
> +	/* protect migartion state */
> +	struct mutex state_mutex;
> +	struct mlx5vf_pci_migration_info vmig;
> +};
> +
> +static int mlx5vf_pci_unquiesce_device(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	return mlx5vf_cmd_resume_vhca(mvdev->core_device.pdev,
> +				      mvdev->vmig.vhca_id,
> +				      MLX5_RESUME_VHCA_IN_OP_MOD_RESUME_MASTER);
> +}
> +
> +static int mlx5vf_pci_quiesce_device(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	return mlx5vf_cmd_suspend_vhca(
> +		mvdev->core_device.pdev, mvdev->vmig.vhca_id,
> +		MLX5_SUSPEND_VHCA_IN_OP_MOD_SUSPEND_MASTER);
> +}
> +
> +static int mlx5vf_pci_unfreeze_device(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	int ret;
> +
> +	ret = mlx5vf_cmd_resume_vhca(mvdev->core_device.pdev,
> +				     mvdev->vmig.vhca_id,
> +				     MLX5_RESUME_VHCA_IN_OP_MOD_RESUME_SLAVE);
> +	if (ret)
> +		return ret;
> +
> +	mvdev->vmig.dev_state &= ~MLX5VF_PCI_FREEZED;
> +	return 0;
> +}
> +
> +static int mlx5vf_pci_freeze_device(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	int ret;
> +
> +	ret = mlx5vf_cmd_suspend_vhca(
> +		mvdev->core_device.pdev, mvdev->vmig.vhca_id,
> +		MLX5_SUSPEND_VHCA_IN_OP_MOD_SUSPEND_SLAVE);
> +	if (ret)
> +		return ret;
> +
> +	mvdev->vmig.dev_state |= MLX5VF_PCI_FREEZED;
> +	return 0;
> +}
> +
> +static int mlx5vf_pci_save_device_data(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	u32 state_size = 0;
> +	int ret;
> +
> +	if (!(mvdev->vmig.dev_state & MLX5VF_PCI_FREEZED))
> +		return -EFAULT;
> +
> +	/* If we already read state no reason to re-read */
> +	if (mvdev->vmig.vhca_state_data.state_size)
> +		return 0;
> +
> +	ret = mlx5vf_cmd_query_vhca_migration_state(
> +		mvdev->core_device.pdev, mvdev->vmig.vhca_id, &state_size);
> +	if (ret)
> +		return ret;
> +
> +	return mlx5vf_cmd_save_vhca_state(mvdev->core_device.pdev,
> +					  mvdev->vmig.vhca_id, state_size,
> +					  &mvdev->vmig.vhca_state_data);
> +}
> +
> +static int mlx5vf_pci_new_write_window(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	struct mlx5_vhca_state_data *state_data = &mvdev->vmig.vhca_state_data;
> +	u32 num_pages_needed;
> +	u64 allocated_ready;
> +	u32 bytes_needed;
> +
> +	/* Check how many bytes are available from previous flows */
> +	WARN_ON(state_data->num_pages * PAGE_SIZE <
> +		state_data->win_start_offset);
> +	allocated_ready = (state_data->num_pages * PAGE_SIZE) -
> +			  state_data->win_start_offset;
> +	WARN_ON(allocated_ready > MLX5VF_MIG_REGION_DATA_SIZE);
> +
> +	bytes_needed = MLX5VF_MIG_REGION_DATA_SIZE - allocated_ready;
> +	if (!bytes_needed)
> +		return 0;
> +
> +	num_pages_needed = DIV_ROUND_UP_ULL(bytes_needed, PAGE_SIZE);
> +	return mlx5vf_add_migration_pages(state_data, num_pages_needed);
> +}
> +
> +static ssize_t
> +mlx5vf_pci_handle_migration_data_size(struct mlx5vf_pci_core_device *mvdev,
> +				      char __user *buf, bool iswrite)
> +{
> +	struct mlx5vf_pci_migration_info *vmig = &mvdev->vmig;
> +	u64 data_size;
> +	int ret;
> +
> +	if (iswrite) {
> +		/* data_size is writable only during resuming state */
> +		if (vmig->vfio_dev_state != VFIO_DEVICE_STATE_RESUMING)
> +			return -EINVAL;
> +
> +		ret = copy_from_user(&data_size, buf, sizeof(data_size));
> +		if (ret)
> +			return -EFAULT;
> +
> +		vmig->vhca_state_data.state_size += data_size;
> +		vmig->vhca_state_data.win_start_offset += data_size;
> +		ret = mlx5vf_pci_new_write_window(mvdev);
> +		if (ret)
> +			return ret;
> +
> +	} else {
> +		if (vmig->vfio_dev_state != VFIO_DEVICE_STATE_SAVING)
> +			return -EINVAL;
> +
> +		data_size = min_t(u64, MLX5VF_MIG_REGION_DATA_SIZE,
> +				  vmig->vhca_state_data.state_size -
> +				  vmig->vhca_state_data.win_start_offset);
> +		ret = copy_to_user(buf, &data_size, sizeof(data_size));
> +		if (ret)
> +			return -EFAULT;
> +	}
> +
> +	vmig->region_state |= MLX5VF_REGION_DATA_SIZE;
> +	return sizeof(data_size);
> +}
> +
> +static ssize_t
> +mlx5vf_pci_handle_migration_data_offset(struct mlx5vf_pci_core_device *mvdev,
> +					char __user *buf, bool iswrite)
> +{
> +	static const u64 data_offset = MLX5VF_MIG_REGION_DATA_OFFSET;
> +	int ret;
> +
> +	/* RO field */
> +	if (iswrite)
> +		return -EFAULT;
> +
> +	ret = copy_to_user(buf, &data_offset, sizeof(data_offset));
> +	if (ret)
> +		return -EFAULT;
> +
> +	return sizeof(data_offset);
> +}
> +
> +static ssize_t
> +mlx5vf_pci_handle_migration_pending_bytes(struct mlx5vf_pci_core_device *mvdev,
> +					  char __user *buf, bool iswrite)
> +{
> +	struct mlx5vf_pci_migration_info *vmig = &mvdev->vmig;
> +	u64 pending_bytes;
> +	int ret;
> +
> +	/* RO field */
> +	if (iswrite)
> +		return -EFAULT;
> +
> +	if (vmig->vfio_dev_state == (VFIO_DEVICE_STATE_SAVING |
> +				     VFIO_DEVICE_STATE_RUNNING)) {
> +		/* In pre-copy state we have no data to return for now,
> +		 * return 0 pending bytes
> +		 */
> +		pending_bytes = 0;
> +	} else {
> +		if (!vmig->vhca_state_data.state_size)
> +			return 0;
> +		pending_bytes = vmig->vhca_state_data.state_size -
> +				vmig->vhca_state_data.win_start_offset;
> +	}
> +
> +	ret = copy_to_user(buf, &pending_bytes, sizeof(pending_bytes));
> +	if (ret)
> +		return -EFAULT;
> +
> +	/* Window moves forward once data from previous iteration was read */
> +	if (vmig->region_state & MLX5VF_REGION_DATA_SIZE)
> +		vmig->vhca_state_data.win_start_offset +=
> +			min_t(u64, MLX5VF_MIG_REGION_DATA_SIZE, pending_bytes);
> +
> +	WARN_ON(vmig->vhca_state_data.win_start_offset >
> +		vmig->vhca_state_data.state_size);
> +
> +	/* New iteration started */
> +	vmig->region_state = MLX5VF_REGION_PENDING_BYTES;
> +	return sizeof(pending_bytes);
> +}
> +
> +static int mlx5vf_load_state(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	if (!mvdev->vmig.vhca_state_data.state_size)
> +		return 0;
> +
> +	return mlx5vf_cmd_load_vhca_state(mvdev->core_device.pdev,
> +					  mvdev->vmig.vhca_id,
> +					  &mvdev->vmig.vhca_state_data);
> +}
> +
> +static void mlx5vf_reset_mig_state(struct mlx5vf_pci_core_device *mvdev)
> +{
> +	struct mlx5vf_pci_migration_info *vmig = &mvdev->vmig;
> +
> +	vmig->region_state = 0;
> +	mlx5vf_reset_vhca_state(&vmig->vhca_state_data);
> +}
> +
> +static int mlx5vf_pci_set_device_state(struct mlx5vf_pci_core_device *mvdev,
> +				       u32 state)
> +{
> +	struct mlx5vf_pci_migration_info *vmig = &mvdev->vmig;
> +	u32 old_state = vmig->vfio_dev_state;
> +	int ret = 0;
> +
> +	if (vfio_is_state_invalid(state) || vfio_is_state_invalid(old_state))
> +		return -EINVAL;

if (!VFIO_DEVICE_STATE_VALID(old_state) || !VFIO_DEVICE_STATE_VALID(state))


> +
> +	/* Running switches off */
> +	if ((old_state & VFIO_DEVICE_STATE_RUNNING) !=
> +	    (state & VFIO_DEVICE_STATE_RUNNING) &&

((old_state ^ state) & VFIO_DEVICE_STATE_RUNNING) ?


> +	    (old_state & VFIO_DEVICE_STATE_RUNNING)) {
> +		ret = mlx5vf_pci_quiesce_device(mvdev);
> +		if (ret)
> +			return ret;
> +		ret = mlx5vf_pci_freeze_device(mvdev);
> +		if (ret) {
> +			vmig->vfio_dev_state = VFIO_DEVICE_STATE_INVALID;


No, the invalid states are specifically unreachable, the uAPI defines
the error state for this purpose.  The states noted as invalid in the
uAPI should be considered reserved at this point.  If only there was a
macro to set an error state... ;)


> +			return ret;
> +		}
> +	}
> +
> +	/* Resuming switches off */
> +	if ((old_state & VFIO_DEVICE_STATE_RESUMING) !=
> +	    (state & VFIO_DEVICE_STATE_RESUMING) &&

A single xor before all of these cases might be worthwhile.  Thanks,

Alex

> +	    (old_state & VFIO_DEVICE_STATE_RESUMING)) {
> +		/* deserialize state into the device */
> +		ret = mlx5vf_load_state(mvdev);
> +		if (ret) {
> +			vmig->vfio_dev_state = VFIO_DEVICE_STATE_INVALID;
> +			return ret;
> +		}
> +	}
> +
> +	/* Resuming switches on */
> +	if ((old_state & VFIO_DEVICE_STATE_RESUMING) !=
> +	    (state & VFIO_DEVICE_STATE_RESUMING) &&
> +	    (state & VFIO_DEVICE_STATE_RESUMING)) {
> +		mlx5vf_reset_mig_state(mvdev);
> +		ret = mlx5vf_pci_new_write_window(mvdev);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	/* Saving switches on */
> +	if ((old_state & VFIO_DEVICE_STATE_SAVING) !=
> +	    (state & VFIO_DEVICE_STATE_SAVING) &&
> +	    (state & VFIO_DEVICE_STATE_SAVING)) {
> +		if (!(state & VFIO_DEVICE_STATE_RUNNING)) {
> +			/* serialize post copy */
> +			ret = mlx5vf_pci_save_device_data(mvdev);
> +			if (ret)
> +				return ret;
> +		}
> +	}
> +
> +	/* Running switches on */
> +	if ((old_state & VFIO_DEVICE_STATE_RUNNING) !=
> +	    (state & VFIO_DEVICE_STATE_RUNNING) &&
> +	    (state & VFIO_DEVICE_STATE_RUNNING)) {
> +		ret = mlx5vf_pci_unfreeze_device(mvdev);
> +		if (ret)
> +			return ret;
> +		ret = mlx5vf_pci_unquiesce_device(mvdev);
> +		if (ret) {
> +			vmig->vfio_dev_state = VFIO_DEVICE_STATE_INVALID;
> +			return ret;
> +		}
> +	}
> +
> +	vmig->vfio_dev_state = state;
> +	return 0;
> +}
> +
> +static ssize_t
> +mlx5vf_pci_handle_migration_device_state(struct mlx5vf_pci_core_device *mvdev,
> +					 char __user *buf, bool iswrite)
> +{
> +	size_t count = sizeof(mvdev->vmig.vfio_dev_state);
> +	int ret;
> +
> +	if (iswrite) {
> +		u32 device_state;
> +
> +		ret = copy_from_user(&device_state, buf, count);
> +		if (ret)
> +			return -EFAULT;
> +
> +		ret = mlx5vf_pci_set_device_state(mvdev, device_state);
> +		if (ret)
> +			return ret;
> +	} else {
> +		ret = copy_to_user(buf, &mvdev->vmig.vfio_dev_state, count);
> +		if (ret)
> +			return -EFAULT;
> +	}
> +
> +	return count;
> +}
> +
> +static ssize_t
> +mlx5vf_pci_copy_user_data_to_device_state(struct mlx5vf_pci_core_device *mvdev,
> +					  char __user *buf, size_t count,
> +					  u64 offset)
> +{
> +	struct mlx5_vhca_state_data *state_data = &mvdev->vmig.vhca_state_data;
> +	char __user *from_buff = buf;
> +	u32 curr_offset;
> +	u32 win_page_offset;
> +	u32 copy_count;
> +	struct page *page;
> +	char *to_buff;
> +	int ret;
> +
> +	curr_offset = state_data->win_start_offset + offset;
> +
> +	do {
> +		page = mlx5vf_get_migration_page(&state_data->mig_data,
> +						 curr_offset);
> +		if (!page)
> +			return -EINVAL;
> +
> +		win_page_offset = curr_offset % PAGE_SIZE;
> +		copy_count = min_t(u32, PAGE_SIZE - win_page_offset, count);
> +
> +		to_buff = kmap_local_page(page);
> +		ret = copy_from_user(to_buff + win_page_offset, from_buff,
> +				     copy_count);
> +		kunmap_local(to_buff);
> +		if (ret)
> +			return -EFAULT;
> +
> +		from_buff += copy_count;
> +		curr_offset += copy_count;
> +		count -= copy_count;
> +	} while (count > 0);
> +
> +	return 0;
> +}
> +
> +static ssize_t
> +mlx5vf_pci_copy_device_state_to_user(struct mlx5vf_pci_core_device *mvdev,
> +				     char __user *buf, u64 offset, size_t count)
> +{
> +	struct mlx5_vhca_state_data *state_data = &mvdev->vmig.vhca_state_data;
> +	char __user *to_buff = buf;
> +	u32 win_available_bytes;
> +	u32 win_page_offset;
> +	u32 copy_count;
> +	u32 curr_offset;
> +	char *from_buff;
> +	struct page *page;
> +	int ret;
> +
> +	win_available_bytes =
> +		min_t(u64, MLX5VF_MIG_REGION_DATA_SIZE,
> +		      mvdev->vmig.vhca_state_data.state_size -
> +			      mvdev->vmig.vhca_state_data.win_start_offset);
> +
> +	if (count + offset > win_available_bytes)
> +		return -EINVAL;
> +
> +	curr_offset = state_data->win_start_offset + offset;
> +
> +	do {
> +		page = mlx5vf_get_migration_page(&state_data->mig_data,
> +						 curr_offset);
> +		if (!page)
> +			return -EINVAL;
> +
> +		win_page_offset = curr_offset % PAGE_SIZE;
> +		copy_count = min_t(u32, PAGE_SIZE - win_page_offset, count);
> +
> +		from_buff = kmap_local_page(page);
> +		ret = copy_to_user(buf, from_buff + win_page_offset,
> +				   copy_count);
> +		kunmap_local(from_buff);
> +		if (ret)
> +			return -EFAULT;
> +
> +		curr_offset += copy_count;
> +		count -= copy_count;
> +		to_buff += copy_count;
> +	} while (count);
> +
> +	return 0;
> +}
> +
> +static ssize_t
> +mlx5vf_pci_migration_data_rw(struct mlx5vf_pci_core_device *mvdev,
> +			     char __user *buf, size_t count, u64 offset,
> +			     bool iswrite)
> +{
> +	int ret;
> +
> +	if (offset + count > MLX5VF_MIG_REGION_DATA_SIZE)
> +		return -EINVAL;
> +
> +	if (iswrite)
> +		ret = mlx5vf_pci_copy_user_data_to_device_state(mvdev, buf,
> +								count, offset);
> +	else
> +		ret = mlx5vf_pci_copy_device_state_to_user(mvdev, buf, offset,
> +							   count);
> +	if (ret)
> +		return ret;
> +	return count;
> +}
> +
> +static ssize_t mlx5vf_pci_mig_rw(struct vfio_pci_core_device *vdev,
> +				 char __user *buf, size_t count, loff_t *ppos,
> +				 bool iswrite)
> +{
> +	struct mlx5vf_pci_core_device *mvdev =
> +		container_of(vdev, struct mlx5vf_pci_core_device, core_device);
> +	u64 pos = *ppos & VFIO_PCI_OFFSET_MASK;
> +	int ret;
> +
> +	mutex_lock(&mvdev->state_mutex);
> +	/* Copy to/from the migration region data section */
> +	if (pos >= MLX5VF_MIG_REGION_DATA_OFFSET) {
> +		ret = mlx5vf_pci_migration_data_rw(
> +			mvdev, buf, count, pos - MLX5VF_MIG_REGION_DATA_OFFSET,
> +			iswrite);
> +		goto end;
> +	}
> +
> +	switch (pos) {
> +	case VFIO_DEVICE_MIGRATION_OFFSET(device_state):
> +		/* This is RW field. */
> +		if (count != sizeof(mvdev->vmig.vfio_dev_state)) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +		ret = mlx5vf_pci_handle_migration_device_state(mvdev, buf,
> +							       iswrite);
> +		break;
> +	case VFIO_DEVICE_MIGRATION_OFFSET(pending_bytes):
> +		/*
> +		 * The number of pending bytes still to be migrated from the
> +		 * vendor driver. This is RO field.
> +		 * Reading this field indicates on the start of a new iteration
> +		 * to get device data.
> +		 *
> +		 */
> +		ret = mlx5vf_pci_handle_migration_pending_bytes(mvdev, buf,
> +								iswrite);
> +		break;
> +	case VFIO_DEVICE_MIGRATION_OFFSET(data_offset):
> +		/*
> +		 * The user application should read data_offset field from the
> +		 * migration region. The user application should read the
> +		 * device data from this offset within the migration region
> +		 * during the _SAVING mode or write the device data during the
> +		 * _RESUMING mode. This is RO field.
> +		 */
> +		ret = mlx5vf_pci_handle_migration_data_offset(mvdev, buf,
> +							      iswrite);
> +		break;
> +	case VFIO_DEVICE_MIGRATION_OFFSET(data_size):
> +		/*
> +		 * The user application should read data_size to get the size
> +		 * in bytes of the data copied to the migration region during
> +		 * the _SAVING state by the device. The user application should
> +		 * write the size in bytes of the data that was copied to
> +		 * the migration region during the _RESUMING state by the user.
> +		 * This is RW field.
> +		 */
> +		ret = mlx5vf_pci_handle_migration_data_size(mvdev, buf,
> +							    iswrite);
> +		break;
> +	default:
> +		ret = -EFAULT;
> +		break;
> +	}
> +
> +end:
> +	mutex_unlock(&mvdev->state_mutex);
> +	return ret;
> +}
> +
> +static struct vfio_pci_regops migration_ops = {
> +	.rw = mlx5vf_pci_mig_rw,
> +};
> +
> +static int mlx5vf_pci_open_device(struct vfio_device *core_vdev)
> +{
> +	struct mlx5vf_pci_core_device *mvdev = container_of(
> +		core_vdev, struct mlx5vf_pci_core_device, core_device.vdev);
> +	struct vfio_pci_core_device *vdev = &mvdev->core_device;
> +	int vf_id;
> +	int ret;
> +
> +	ret = vfio_pci_core_enable(vdev);
> +	if (ret)
> +		return ret;
> +
> +	if (!mvdev->migrate_cap) {
> +		vfio_pci_core_finish_enable(vdev);
> +		return 0;
> +	}
> +
> +	vf_id = pci_iov_vf_id(vdev->pdev);
> +	if (vf_id < 0) {
> +		ret = vf_id;
> +		goto out_disable;
> +	}
> +
> +	ret = mlx5vf_cmd_get_vhca_id(vdev->pdev, vf_id + 1,
> +				     &mvdev->vmig.vhca_id);
> +	if (ret)
> +		goto out_disable;
> +
> +	ret = vfio_pci_register_dev_region(vdev, VFIO_REGION_TYPE_MIGRATION,
> +					   VFIO_REGION_SUBTYPE_MIGRATION,
> +					   &migration_ops,
> +					   MLX5VF_MIG_REGION_DATA_OFFSET +
> +					   MLX5VF_MIG_REGION_DATA_SIZE,
> +					   VFIO_REGION_INFO_FLAG_READ |
> +					   VFIO_REGION_INFO_FLAG_WRITE,
> +					   NULL);
> +	if (ret)
> +		goto out_disable;
> +
> +	mutex_init(&mvdev->state_mutex);
> +	mvdev->vmig.vfio_dev_state = VFIO_DEVICE_STATE_RUNNING;
> +	vfio_pci_core_finish_enable(vdev);
> +	return 0;
> +out_disable:
> +	vfio_pci_core_disable(vdev);
> +	return ret;
> +}
> +
> +static void mlx5vf_pci_close_device(struct vfio_device *core_vdev)
> +{
> +	struct mlx5vf_pci_core_device *mvdev = container_of(
> +		core_vdev, struct mlx5vf_pci_core_device, core_device.vdev);
> +
> +	vfio_pci_core_close_device(core_vdev);
> +	mlx5vf_reset_mig_state(mvdev);
> +}
> +
> +static const struct vfio_device_ops mlx5vf_pci_ops = {
> +	.name = "mlx5-vfio-pci",
> +	.open_device = mlx5vf_pci_open_device,
> +	.close_device = mlx5vf_pci_close_device,
> +	.ioctl = vfio_pci_core_ioctl,
> +	.read = vfio_pci_core_read,
> +	.write = vfio_pci_core_write,
> +	.mmap = vfio_pci_core_mmap,
> +	.request = vfio_pci_core_request,
> +	.match = vfio_pci_core_match,
> +};
> +
> +static int mlx5vf_pci_probe(struct pci_dev *pdev,
> +			    const struct pci_device_id *id)
> +{
> +	struct mlx5vf_pci_core_device *mvdev;
> +	int ret;
> +
> +	mvdev = kzalloc(sizeof(*mvdev), GFP_KERNEL);
> +	if (!mvdev)
> +		return -ENOMEM;
> +	vfio_pci_core_init_device(&mvdev->core_device, pdev, &mlx5vf_pci_ops);
> +
> +	if (pdev->is_virtfn) {
> +		struct mlx5_core_dev *mdev =
> +			mlx5_vf_get_core_dev(pdev);
> +
> +		if (mdev) {
> +			if (MLX5_CAP_GEN(mdev, migration))
> +				mvdev->migrate_cap = 1;
> +			mlx5_vf_put_core_dev(mdev);
> +		}
> +	}
> +
> +	ret = vfio_pci_core_register_device(&mvdev->core_device);
> +	if (ret)
> +		goto out_free;
> +
> +	dev_set_drvdata(&pdev->dev, mvdev);
> +	return 0;
> +
> +out_free:
> +	vfio_pci_core_uninit_device(&mvdev->core_device);
> +	kfree(mvdev);
> +	return ret;
> +}
> +
> +static void mlx5vf_pci_remove(struct pci_dev *pdev)
> +{
> +	struct mlx5vf_pci_core_device *mvdev = dev_get_drvdata(&pdev->dev);
> +
> +	vfio_pci_core_unregister_device(&mvdev->core_device);
> +	vfio_pci_core_uninit_device(&mvdev->core_device);
> +	kfree(mvdev);
> +}
> +
> +static const struct pci_device_id mlx5vf_pci_table[] = {
> +	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_MELLANOX, 0x101e) }, /* ConnectX Family mlx5Gen Virtual Function */
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(pci, mlx5vf_pci_table);
> +
> +static struct pci_driver mlx5vf_pci_driver = {
> +	.name = KBUILD_MODNAME,
> +	.id_table = mlx5vf_pci_table,
> +	.probe = mlx5vf_pci_probe,
> +	.remove = mlx5vf_pci_remove,
> +	.err_handler = &vfio_pci_core_err_handlers,
> +};
> +
> +static void __exit mlx5vf_pci_cleanup(void)
> +{
> +	pci_unregister_driver(&mlx5vf_pci_driver);
> +}
> +
> +static int __init mlx5vf_pci_init(void)
> +{
> +	return pci_register_driver(&mlx5vf_pci_driver);
> +}
> +
> +module_init(mlx5vf_pci_init);
> +module_exit(mlx5vf_pci_cleanup);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Max Gurtovoy <mgurtovoy@...dia.com>");
> +MODULE_AUTHOR("Yishai Hadas <yishaih@...dia.com>");
> +MODULE_DESCRIPTION(
> +	"MLX5 VFIO PCI - User Level meta-driver for MLX5 device family");

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