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Subject: Re: [PATCH v4 01/10] vfio/fsl-mc: Add VFIO framework skeleton for
 fsl-mc devices
To:     Diana Craciun OSS <diana.craciun@oss.nxp.com>,
        alex.williamson@redhat.com, kvm@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, bharatb.linux@gmail.com,
        laurentiu.tudor@nxp.com, Bharat Bhushan <Bharat.Bhushan@nxp.com>
References: <20200826093315.5279-1-diana.craciun@oss.nxp.com>
 <20200826093315.5279-2-diana.craciun@oss.nxp.com>
 <4636da7d-0c97-4c14-cfac-bdb4c9e6cd83@redhat.com>
 <da339828-1696-7d46-3548-3b99746e92fe@oss.nxp.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <11a45457-81c6-287a-9a8f-4d789ba2e82f@redhat.com>
Date:   Fri, 4 Sep 2020 16:11:27 +0200
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Hi Diana,

On 9/4/20 3:59 PM, Diana Craciun OSS wrote:
> Hi Eric,
> 
> On 9/3/2020 5:06 PM, Auger Eric wrote:
>> Hi Diana,
>>
>> On 8/26/20 11:33 AM, Diana Craciun wrote:
>>> From: Bharat Bhushan <Bharat.Bhushan@nxp.com>
>>>
>>> DPAA2 (Data Path Acceleration Architecture) consists in
>>> mechanisms for processing Ethernet packets, queue management,
>>> accelerators, etc.
>>>
>>> The Management Complex (mc) is a hardware entity that manages the DPAA2
>>> hardware resources. It provides an object-based abstraction for software
>>> drivers to use the DPAA2 hardware. The MC mediates operations such as
>>> create, discover, destroy of DPAA2 objects.
>>> The MC provides memory-mapped I/O command interfaces (MC portals) which
>>> DPAA2 software drivers use to operate on DPAA2 objects.
>>>
>>> A DPRC is a container object that holds other types of DPAA2 objects.
>>> Each object in the DPRC is a Linux device and bound to a driver.
>>> The MC-bus driver is a platform driver (different from PCI or platform
>>> bus). The DPRC driver does runtime management of a bus instance. It
>>> performs the initial scan of the DPRC and handles changes in the DPRC
>>> configuration (adding/removing objects).
>>>
>>> All objects inside a container share the same hardware isolation
>>> context, meaning that only an entire DPRC can be assigned to
>>> a virtual machine.
>>> When a container is assigned to a virtual machine, all the objects
>>> within that container are assigned to that virtual machine.
>>> The DPRC container assigned to the virtual machine is not allowed
>>> to change contents (add/remove objects) by the guest. The restriction
>>> is set by the host and enforced by the mc hardware.
>>>
>>> The DPAA2 objects can be directly assigned to the guest. However
>>> the MC portals (the memory mapped command interface to the MC) need
>>> to be emulated because there are commands that configure the
>>> interrupts and the isolation IDs which are virtual in the guest.
>>>
>>> Example:
>>> echo vfio-fsl-mc > /sys/bus/fsl-mc/devices/dprc.2/driver_override
>>> echo dprc.2 > /sys/bus/fsl-mc/drivers/vfio-fsl-mc/bind
>>>
>>> The dprc.2 is bound to the VFIO driver and all the objects within
>>> dprc.2 are going to be bound to the VFIO driver.
>>>
>>> This patch adds the infrastructure for VFIO support for fsl-mc
>>> devices. Subsequent patches will add support for binding and secure
>>> assigning these devices using VFIO.
>>>
>>> More details about the DPAA2 objects can be found here:
>>> Documentation/networking/device_drivers/freescale/dpaa2/overview.rst
>>>
>>> Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com>
>>> Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
>>> ---
>>>   MAINTAINERS                               |   6 +
>>>   drivers/vfio/Kconfig                      |   1 +
>>>   drivers/vfio/Makefile                     |   1 +
>>>   drivers/vfio/fsl-mc/Kconfig               |   9 ++
>>>   drivers/vfio/fsl-mc/Makefile              |   4 +
>>>   drivers/vfio/fsl-mc/vfio_fsl_mc.c         | 160 ++++++++++++++++++++++
>>>   drivers/vfio/fsl-mc/vfio_fsl_mc_private.h |  14 ++
>>>   include/uapi/linux/vfio.h                 |   1 +
>>>   8 files changed, 196 insertions(+)
>>>   create mode 100644 drivers/vfio/fsl-mc/Kconfig
>>>   create mode 100644 drivers/vfio/fsl-mc/Makefile
>>>   create mode 100644 drivers/vfio/fsl-mc/vfio_fsl_mc.c
>>>   create mode 100644 drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 3b186ade3597..f3f9ea108588 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -18229,6 +18229,12 @@ F:    drivers/vfio/
>>>   F:    include/linux/vfio.h
>>>   F:    include/uapi/linux/vfio.h
>>>   +VFIO FSL-MC DRIVER
>>> +M:    Diana Craciun <diana.craciun@oss.nxp.com>
>>> +L:    kvm@vger.kernel.org
>>> +S:    Maintained
>>> +F:    drivers/vfio/fsl-mc/
>>> +
>>>   VFIO MEDIATED DEVICE DRIVERS
>>>   M:    Kirti Wankhede <kwankhede@nvidia.com>
>>>   L:    kvm@vger.kernel.org
>>> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
>>> index fd17db9b432f..5533df91b257 100644
>>> --- a/drivers/vfio/Kconfig
>>> +++ b/drivers/vfio/Kconfig
>>> @@ -47,4 +47,5 @@ menuconfig VFIO_NOIOMMU
>>>   source "drivers/vfio/pci/Kconfig"
>>>   source "drivers/vfio/platform/Kconfig"
>>>   source "drivers/vfio/mdev/Kconfig"
>>> +source "drivers/vfio/fsl-mc/Kconfig"
>>>   source "virt/lib/Kconfig"
>>> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
>>> index de67c4725cce..fee73f3d9480 100644
>>> --- a/drivers/vfio/Makefile
>>> +++ b/drivers/vfio/Makefile
>>> @@ -9,3 +9,4 @@ obj-$(CONFIG_VFIO_SPAPR_EEH) += vfio_spapr_eeh.o
>>>   obj-$(CONFIG_VFIO_PCI) += pci/
>>>   obj-$(CONFIG_VFIO_PLATFORM) += platform/
>>>   obj-$(CONFIG_VFIO_MDEV) += mdev/
>>> +obj-$(CONFIG_VFIO_FSL_MC) += fsl-mc/
>>> diff --git a/drivers/vfio/fsl-mc/Kconfig b/drivers/vfio/fsl-mc/Kconfig
>>> new file mode 100644
>>> index 000000000000..b1a527d6b6f2
>>> --- /dev/null
>>> +++ b/drivers/vfio/fsl-mc/Kconfig
>>> @@ -0,0 +1,9 @@
>>> +config VFIO_FSL_MC
>>> +    tristate "VFIO support for QorIQ DPAA2 fsl-mc bus devices"
>>> +    depends on VFIO && FSL_MC_BUS && EVENTFD
>>> +    help
>>> +      Driver to enable support for the VFIO QorIQ DPAA2 fsl-mc
>>> +      (Management Complex) devices. This is required to passthrough
>>> +      fsl-mc bus devices using the VFIO framework.
>>> +
>>> +      If you don't know what to do here, say N.
>>> diff --git a/drivers/vfio/fsl-mc/Makefile b/drivers/vfio/fsl-mc/Makefile
>>> new file mode 100644
>>> index 000000000000..0c6e5d2ddaae
>>> --- /dev/null
>>> +++ b/drivers/vfio/fsl-mc/Makefile
>>> @@ -0,0 +1,4 @@
>>> +# SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
>>> +
>>> +vfio-fsl-mc-y := vfio_fsl_mc.o
>>> +obj-$(CONFIG_VFIO_FSL_MC) += vfio-fsl-mc.o
>>> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
>>> b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
>>> new file mode 100644
>>> index 000000000000..8b53c2a25b32
>>> --- /dev/null
>>> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
>>> @@ -0,0 +1,160 @@
>>> +// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
>>> +/*
>>> + * Copyright 2013-2016 Freescale Semiconductor Inc.
>>> + * Copyright 2016-2017,2019-2020 NXP
>>> + */
>>> +
>>> +#include <linux/device.h>
>>> +#include <linux/iommu.h>
>>> +#include <linux/module.h>
>>> +#include <linux/mutex.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/types.h>
>>> +#include <linux/vfio.h>
>>> +#include <linux/fsl/mc.h>
>>> +
>>> +#include "vfio_fsl_mc_private.h"
>>> +
>>> +static int vfio_fsl_mc_open(void *device_data)
>>> +{
>>> +    if (!try_module_get(THIS_MODULE))
>>> +        return -ENODEV;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static void vfio_fsl_mc_release(void *device_data)
>>> +{
>>> +    module_put(THIS_MODULE);
>>> +}
>>> +
>>> +static long vfio_fsl_mc_ioctl(void *device_data, unsigned int cmd,
>>> +                  unsigned long arg)
>>> +{
>>> +    switch (cmd) {
>>> +    case VFIO_DEVICE_GET_INFO:
>>> +    {
>>> +        return -ENOTTY;
>>> +    }
>>> +    case VFIO_DEVICE_GET_REGION_INFO:
>>> +    {
>>> +        return -ENOTTY;
>>> +    }
>>> +    case VFIO_DEVICE_GET_IRQ_INFO:
>>> +    {
>>> +        return -ENOTTY;
>>> +    }
>>> +    case VFIO_DEVICE_SET_IRQS:
>>> +    {
>>> +        return -ENOTTY;
>>> +    }
>>> +    case VFIO_DEVICE_RESET:
>>> +    {
>>> +        return -ENOTTY;
>>> +    }
>>> +    default:
>>> +        return -ENOTTY;
>>> +    }
>>> +}
>>> +
>>> +static ssize_t vfio_fsl_mc_read(void *device_data, char __user *buf,
>>> +                size_t count, loff_t *ppos)
>>> +{
>>> +    return -EINVAL;
>>> +}
>>> +
>>> +static ssize_t vfio_fsl_mc_write(void *device_data, const char
>>> __user *buf,
>>> +                 size_t count, loff_t *ppos)
>>> +{
>>> +    return -EINVAL;
>>> +}
>>> +
>>> +static int vfio_fsl_mc_mmap(void *device_data, struct vm_area_struct
>>> *vma)
>>> +{
>>> +    return -EINVAL;
>>> +}
>>> +
>>> +static const struct vfio_device_ops vfio_fsl_mc_ops = {
>>> +    .name        = "vfio-fsl-mc",
>>> +    .open        = vfio_fsl_mc_open,
>>> +    .release    = vfio_fsl_mc_release,
>>> +    .ioctl        = vfio_fsl_mc_ioctl,
>>> +    .read        = vfio_fsl_mc_read,
>>> +    .write        = vfio_fsl_mc_write,
>>> +    .mmap        = vfio_fsl_mc_mmap,
>>> +};
>>> +
>>> +static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
>>> +{
>>> +    struct iommu_group *group;
>>> +    struct vfio_fsl_mc_device *vdev;
>>> +    struct device *dev = &mc_dev->dev;
>>> +    int ret;
>>> +
>>> +    group = vfio_iommu_group_get(dev);
>>> +    if (!group) {
>>> +        dev_err(dev, "%s: VFIO: No IOMMU group\n", __func__);
>>> +        return -EINVAL;
>>> +    }
>>> +
>>> +    vdev = devm_kzalloc(dev, sizeof(*vdev), GFP_KERNEL);
>>> +    if (!vdev) {
>>> +        vfio_iommu_group_put(group, dev);
>>> +        return -ENOMEM;
>>> +    }
>>> +
>>> +    vdev->mc_dev = mc_dev;
>>> +
>>> +    ret = vfio_add_group_dev(dev, &vfio_fsl_mc_ops, vdev);
>>> +    if (ret) {
>>> +        dev_err(dev, "%s: Failed to add to vfio group\n", __func__);
>>> +        vfio_iommu_group_put(group, dev);
>>> +        return ret;
>>> +    }
>>> +
>>> +    return ret;
>> nit: introduce out_group_put: as in other files
>> This will be usable also in subsequent patches
>>> +}
>>> +
>>> +static int vfio_fsl_mc_remove(struct fsl_mc_device *mc_dev)
>>> +{
>>> +    struct vfio_fsl_mc_device *vdev;
>>> +    struct device *dev = &mc_dev->dev;
>>> +
>>> +    vdev = vfio_del_group_dev(dev);
>>> +    if (!vdev)
>>> +        return -EINVAL;
>>> +
>>> +    vfio_iommu_group_put(mc_dev->dev.iommu_group, dev);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/*
>>> + * vfio-fsl_mc is a meta-driver, so use driver_override interface to
>>> + * bind a fsl_mc container with this driver and match_id_table is NULL.
>>> + */
>>> +static struct fsl_mc_driver vfio_fsl_mc_driver = {
>>> +    .probe        = vfio_fsl_mc_probe,
>>> +    .remove        = vfio_fsl_mc_remove,
>>> +    .match_id_table = NULL,
>> not needed?
> 
> The driver will always match on driver_override, there is no need for
> static ids.
I rather meant do you really need to initialize it? I guess it is the
same in vfio_platform and there is no such init.

Thanks

Eric
> 
>>> +    .driver    = {
>>> +        .name    = "vfio-fsl-mc",
>>> +        .owner    = THIS_MODULE,
>>> +    },
>>> +};
>>> +
>>> +static int __init vfio_fsl_mc_driver_init(void)
>>> +{
>>> +    return fsl_mc_driver_register(&vfio_fsl_mc_driver);
>>> +}
>>> +
>>> +static void __exit vfio_fsl_mc_driver_exit(void)
>>> +{
>>> +    fsl_mc_driver_unregister(&vfio_fsl_mc_driver);
>>> +}
>>> +
>>> +module_init(vfio_fsl_mc_driver_init);
>>> +module_exit(vfio_fsl_mc_driver_exit);
>>> +
>>> +MODULE_LICENSE("GPL v2");
>> Don't you need MODULE_LICENSE("Dual BSD/GPL"); ?
> 
> Yes, will change.
> 
>>> +MODULE_DESCRIPTION("VFIO for FSL-MC devices - User Level meta-driver");
>>> diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
>>> b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
>>> new file mode 100644
>>> index 000000000000..e79cc116f6b8
>>> --- /dev/null
>>> +++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_private.h
>>> @@ -0,0 +1,14 @@
>>> +/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
>>> +/*
>>> + * Copyright 2013-2016 Freescale Semiconductor Inc.
>>> + * Copyright 2016,2019-2020 NXP
>>> + */
>>> +
>>> +#ifndef VFIO_FSL_MC_PRIVATE_H
>>> +#define VFIO_FSL_MC_PRIVATE_H
>>> +
>>> +struct vfio_fsl_mc_device {
>>> +    struct fsl_mc_device        *mc_dev;
>>> +};
>>> +
>>> +#endif /* VFIO_FSL_MC_PRIVATE_H */
>>> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
>>> index 920470502329..95deac891378 100644
>>> --- a/include/uapi/linux/vfio.h
>>> +++ b/include/uapi/linux/vfio.h
>>> @@ -201,6 +201,7 @@ struct vfio_device_info {
>>>   #define VFIO_DEVICE_FLAGS_AMBA  (1 << 3)    /* vfio-amba device */
>>>   #define VFIO_DEVICE_FLAGS_CCW    (1 << 4)    /* vfio-ccw device */
>>>   #define VFIO_DEVICE_FLAGS_AP    (1 << 5)    /* vfio-ap device */
>>> +#define VFIO_DEVICE_FLAGS_FSL_MC (1 << 6)    /* vfio-fsl-mc device */
>>>       __u32    num_regions;    /* Max region index + 1 */
>>>       __u32    num_irqs;    /* Max IRQ index + 1 */
>>>   };
>>>
>> Thanks
>>
>> Eric
>>
> 
> Thanks,
> Diana
>