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Message-ID: <4c851046-35f8-28aa-03dd-859f2ade3446@linux.microsoft.com>
Date: Wed, 4 Aug 2021 00:42:22 +0530
From: Praveen Kumar <kumarpraveen@...ux.microsoft.com>
To: Wei Liu <wei.liu@...nel.org>,
Linux on Hyper-V List <linux-hyperv@...r.kernel.org>
Cc: virtualization@...ts.linux-foundation.org,
Linux Kernel List <linux-kernel@...r.kernel.org>,
Michael Kelley <mikelley@...rosoft.com>,
Vineeth Pillai <viremana@...ux.microsoft.com>,
Sunil Muthuswamy <sunilmut@...rosoft.com>,
Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
pasha.tatashin@...een.com, Jonathan Corbet <corbet@....net>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Stephen Hemminger <sthemmin@...rosoft.com>,
Dexuan Cui <decui@...rosoft.com>,
Lillian Grassin-Drake <ligrassi@...rosoft.com>,
Muminul Islam <muislam@...rosoft.com>,
"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [RFC v1 7/8] mshv: implement in-kernel device framework
On 09-07-2021 17:13, Wei Liu wrote:
> This is basically the same code adopted from KVM. The main user case is
> the future MSHV-VFIO bridge device. We don't have any plan to support
> in-kernel device emulation yet, but it wouldn't hurt to make the code
> more flexible.
>
> Signed-off-by: Wei Liu <wei.liu@...nel.org>
> ---
> Documentation/virt/mshv/api.rst | 12 +++
> drivers/hv/mshv_main.c | 181 ++++++++++++++++++++++++++++++++
> include/linux/mshv.h | 57 ++++++++++
> include/uapi/linux/mshv.h | 36 +++++++
> 4 files changed, 286 insertions(+)
>
> diff --git a/Documentation/virt/mshv/api.rst b/Documentation/virt/mshv/api.rst
> index 56a6edfcfe29..7d35dd589831 100644
> --- a/Documentation/virt/mshv/api.rst
> +++ b/Documentation/virt/mshv/api.rst
> @@ -170,4 +170,16 @@ Can be used to get/set various properties of a partition.
> Some properties can only be set at partition creation. For these, there are
> parameters in MSHV_CREATE_PARTITION.
>
> +3.12 MSHV_CREATE_DEVICE
> +-----------------------
> +:Type: partition ioctl
> +:Parameters: struct mshv_create_device
> +:Returns: 0 on success
> +
> +Can be used to create an in-kernel device.
> +
> +If the MSHV_CREATE_DEVICE_TEST flag is set, only test whether the
> +device type is supported (not necessarily whether it can be created
> +in the current vm).
>
> +Currently only supports VFIO type device.
> diff --git a/drivers/hv/mshv_main.c b/drivers/hv/mshv_main.c
> index 4cbc520471e4..84c774a561de 100644
> --- a/drivers/hv/mshv_main.c
> +++ b/drivers/hv/mshv_main.c
> @@ -20,6 +20,8 @@
> #include <linux/random.h>
> #include <linux/mshv.h>
> #include <linux/mshv_eventfd.h>
> +#include <linux/hyperv.h>
> +#include <linux/nospec.h>
> #include <asm/mshyperv.h>
>
> #include "mshv.h"
> @@ -33,6 +35,7 @@ static int mshv_vp_release(struct inode *inode, struct file *filp);
> static long mshv_vp_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
> static struct mshv_partition *mshv_partition_get(struct mshv_partition *partition);
> static void mshv_partition_put(struct mshv_partition *partition);
> +static void mshv_partition_put_no_destroy(struct mshv_partition *partition);
> static int mshv_partition_release(struct inode *inode, struct file *filp);
> static long mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
> static int mshv_dev_open(struct inode *inode, struct file *filp);
> @@ -912,6 +915,172 @@ mshv_partition_ioctl_set_msi_routing(struct mshv_partition *partition,
> return ret;
> }
>
> +static int mshv_device_ioctl_attr(struct mshv_device *dev,
> + int (*accessor)(struct mshv_device *dev,
> + struct mshv_device_attr *attr),
> + unsigned long arg)
> +{
> + struct mshv_device_attr attr;
> +
> + if (!accessor)
> + return -EPERM;
> +
> + if (copy_from_user(&attr, (void __user *)arg, sizeof(attr)))
> + return -EFAULT;
> +
> + return accessor(dev, &attr);
> +}
> +
> +static long mshv_device_ioctl(struct file *filp, unsigned int ioctl,
> + unsigned long arg)
> +{
> + struct mshv_device *dev = filp->private_data;
> +
> + switch (ioctl) {
> + case MSHV_SET_DEVICE_ATTR:
> + return mshv_device_ioctl_attr(dev, dev->ops->set_attr, arg);
> + case MSHV_GET_DEVICE_ATTR:
> + return mshv_device_ioctl_attr(dev, dev->ops->get_attr, arg);
> + case MSHV_HAS_DEVICE_ATTR:
> + return mshv_device_ioctl_attr(dev, dev->ops->has_attr, arg);
> + default:
> + if (dev->ops->ioctl)
> + return dev->ops->ioctl(dev, ioctl, arg);
> +
> + return -ENOTTY;
> + }
Have seen some static analyzer tool cribbing here of not returning any error.
If you feel OK, please move the 'return -ENOTTY' down after switch block. Thanks.
> +}
> +
> +static int mshv_device_release(struct inode *inode, struct file *filp)
> +{
> + struct mshv_device *dev = filp->private_data;
> + struct mshv_partition *partition = dev->partition;
> +
> + if (dev->ops->release) {
> + mutex_lock(&partition->mutex);
> + list_del(&dev->partition_node);
> + dev->ops->release(dev);
> + mutex_unlock(&partition->mutex);
> + }
> +
> + mshv_partition_put(partition);
> + return 0;
> +}
> +
> +static const struct file_operations mshv_device_fops = {
> + .unlocked_ioctl = mshv_device_ioctl,
> + .release = mshv_device_release,
> +};
> +
> +static const struct mshv_device_ops *mshv_device_ops_table[MSHV_DEV_TYPE_MAX];
> +
> +int mshv_register_device_ops(const struct mshv_device_ops *ops, u32 type)
> +{
> + if (type >= ARRAY_SIZE(mshv_device_ops_table))
> + return -ENOSPC;
> +
> + if (mshv_device_ops_table[type] != NULL)
> + return -EEXIST;
> +
> + mshv_device_ops_table[type] = ops;
> + return 0;
> +}
> +
> +void mshv_unregister_device_ops(u32 type)
> +{
> + if (type >= ARRAY_SIZE(mshv_device_ops_table))
> + return;
> + mshv_device_ops_table[type] = NULL;
> +}
> +
> +static long
> +mshv_partition_ioctl_create_device(struct mshv_partition *partition,
> + void __user *user_args)
> +{
> + long r;
> + struct mshv_create_device tmp, *cd;
> + struct mshv_device *dev;
> + const struct mshv_device_ops *ops;
> + int type;
> +
> + if (copy_from_user(&tmp, user_args, sizeof(tmp))) {
> + r = -EFAULT;
> + goto out;
> + }
> +
> + cd = &tmp;
> +
> + if (cd->type >= ARRAY_SIZE(mshv_device_ops_table)) {
> + r = -ENODEV;
> + goto out;
> + }
> +
> + type = array_index_nospec(cd->type, ARRAY_SIZE(mshv_device_ops_table));
> + ops = mshv_device_ops_table[type];
> + if (ops == NULL) {
> + r = -ENODEV;
> + goto out;
> + }
> +
> + if (cd->flags & MSHV_CREATE_DEVICE_TEST) {
> + r = 0;
> + goto out;
> + }
> +
> + dev = kzalloc(sizeof(*dev), GFP_KERNEL_ACCOUNT);
> + if (!dev) {
> + r = -ENOMEM;
> + goto out;
> + }
> +
> + dev->ops = ops;
> + dev->partition = partition;
> +
> + r = ops->create(dev, type);
> + if (r < 0) {
> + kfree(dev);
> + goto out;
> + }
> +
> + list_add(&dev->partition_node, &partition->devices);
> +
> + if (ops->init)
> + ops->init(dev);
> +
> + mshv_partition_get(partition);
> + r = anon_inode_getfd(ops->name, &mshv_device_fops, dev, O_RDWR | O_CLOEXEC);
> + if (r < 0) {
> + mshv_partition_put_no_destroy(partition);
> + list_del(&dev->partition_node);
> + ops->destroy(dev);
I hope ops->destroy will free dev as well ?
> + goto out;
> + }
> +
> + cd->fd = r;
> + r = 0;
> +
> + if (copy_to_user(user_args, &tmp, sizeof(tmp))) {
> + r = -EFAULT;
I don't think we will be cleaning up anything ? Or do we need to?
> + goto out;
> + }
> +out:
> + return r;
> +}
> +
Regards,
~Praveen.
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