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SubjectRe: [PATCH v10 10/26] gunyah: vm_mgr: Introduce basic VM Manager
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On 14/02/2023 21:23, Elliot Berman wrote:
>
> Gunyah VM manager is a kernel moduel which exposes an interface to
> Gunyah userspace to load, run, and interact with other Gunyah virtual
> machines. The interface is a character device at /dev/gunyah.
>
> Add a basic VM manager driver. Upcoming patches will add more ioctls
> into this driver.
>
> Co-developed-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Prakruthi Deepak Heragu <quic_pheragu@quicinc.com>
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> ---
> .../userspace-api/ioctl/ioctl-number.rst | 1 +
> drivers/virt/gunyah/Makefile | 2 +-
> drivers/virt/gunyah/rsc_mgr.c | 37 +++++-
> drivers/virt/gunyah/vm_mgr.c | 118 ++++++++++++++++++
> drivers/virt/gunyah/vm_mgr.h | 22 ++++
> include/uapi/linux/gunyah.h | 23 ++++
> 6 files changed, 201 insertions(+), 2 deletions(-)
> create mode 100644 drivers/virt/gunyah/vm_mgr.c
> create mode 100644 drivers/virt/gunyah/vm_mgr.h
> create mode 100644 include/uapi/linux/gunyah.h
>
> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> index 0a1882e296ae..2513324ae7be 100644
> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> @@ -137,6 +137,7 @@ Code Seq# Include File Comments
> 'F' DD video/sstfb.h conflict!
> 'G' 00-3F drivers/misc/sgi-gru/grulib.h conflict!
> 'G' 00-0F xen/gntalloc.h, xen/gntdev.h conflict!
> +'G' 00-0f linux/gunyah.h conflict!
> 'H' 00-7F linux/hiddev.h conflict!
> 'H' 00-0F linux/hidraw.h conflict!
> 'H' 01 linux/mei.h conflict!
> diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
> index de29769f2f3f..03951cf82023 100644
> --- a/drivers/virt/gunyah/Makefile
> +++ b/drivers/virt/gunyah/Makefile
> @@ -2,5 +2,5 @@
>
> obj-$(CONFIG_GUNYAH) += gunyah.o
>
> -gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o
> +gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o vm_mgr.o
> obj-$(CONFIG_GUNYAH) += gunyah_rsc_mgr.o
> diff --git a/drivers/virt/gunyah/rsc_mgr.c b/drivers/virt/gunyah/rsc_mgr.c
> index 2a47139873a8..73c5a6b7cbbc 100644
> --- a/drivers/virt/gunyah/rsc_mgr.c
> +++ b/drivers/virt/gunyah/rsc_mgr.c
> @@ -16,8 +16,10 @@
> #include <linux/completion.h>
> #include <linux/gunyah_rsc_mgr.h>
> #include <linux/platform_device.h>
> +#include <linux/miscdevice.h>
>
> #include "rsc_mgr.h"
> +#include "vm_mgr.h"
>
> #define RM_RPC_API_VERSION_MASK GENMASK(3, 0)
> #define RM_RPC_HEADER_WORDS_MASK GENMASK(7, 4)
> @@ -103,6 +105,8 @@ struct gh_rm {
> struct kmem_cache *cache;
> struct mutex send_lock;
> struct blocking_notifier_head nh;
> +
> + struct miscdevice miscdev;
> };
>
> static struct gh_rm_connection *gh_rm_alloc_connection(__le32 msg_id, u8 type)
> @@ -509,6 +513,21 @@ void put_gh_rm(struct gh_rm *rm)
> }
> EXPORT_SYMBOL_GPL(put_gh_rm);
>
> +static long gh_dev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> +{
> + struct miscdevice *miscdev = filp->private_data;
> + struct gh_rm *rm = container_of(miscdev, struct gh_rm, miscdev);
> +
> + return gh_dev_vm_mgr_ioctl(rm, cmd, arg);
> +}
> +
> +static const struct file_operations gh_dev_fops = {
> + .owner = THIS_MODULE,
> + .unlocked_ioctl = gh_dev_ioctl,
> + .compat_ioctl = compat_ptr_ioctl,
> + .llseek = noop_llseek,
> +};
> +
> static int gh_msgq_platform_probe_direction(struct platform_device *pdev,
> bool tx, int idx, struct gunyah_resource *ghrsc)
> {
> @@ -567,7 +586,22 @@ static int gh_rm_drv_probe(struct platform_device *pdev)
> rm->msgq_client.rx_callback = gh_rm_msgq_rx_data;
> rm->msgq_client.tx_done = gh_rm_msgq_tx_done;
>
> - return gh_msgq_init(&pdev->dev, &rm->msgq, &rm->msgq_client, &rm->tx_ghrsc, &rm->rx_ghrsc);
> + ret = gh_msgq_init(&pdev->dev, &rm->msgq, &rm->msgq_client, &rm->tx_ghrsc, &rm->rx_ghrsc);
> + if (ret)
> + goto err_cache;
> +
> + rm->miscdev.name = "gunyah";
> + rm->miscdev.minor = MISC_DYNAMIC_MINOR;
> + rm->miscdev.fops = &gh_dev_fops;
> +
> + ret = misc_register(&rm->miscdev);
> + if (ret)
> + goto err_msgq;
> +
> + return 0;
> +err_msgq:
> + mbox_free_channel(gh_msgq_chan(&rm->msgq));
> + gh_msgq_remove(&rm->msgq);
> err_cache:
> kmem_cache_destroy(rm->cache);
> return ret;
> @@ -577,6 +611,7 @@ static int gh_rm_drv_remove(struct platform_device *pdev)
> {
> struct gh_rm *rm = platform_get_drvdata(pdev);
>
> + misc_deregister(&rm->miscdev);
> mbox_free_channel(gh_msgq_chan(&rm->msgq));
> gh_msgq_remove(&rm->msgq);
> kmem_cache_destroy(rm->cache);
> diff --git a/drivers/virt/gunyah/vm_mgr.c b/drivers/virt/gunyah/vm_mgr.c
> new file mode 100644
> index 000000000000..fd890a57172e
> --- /dev/null
> +++ b/drivers/virt/gunyah/vm_mgr.c
> @@ -0,0 +1,118 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#define pr_fmt(fmt) "gh_vm_mgr: " fmt
> +
> +#include <linux/anon_inodes.h>
> +#include <linux/file.h>
> +#include <linux/gunyah_rsc_mgr.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +
> +#include <uapi/linux/gunyah.h>
> +
> +#include "vm_mgr.h"
> +
> +static void gh_vm_free(struct work_struct *work)
> +{
> + struct gh_vm *ghvm = container_of(work, struct gh_vm, free_work);
> + int ret;
> +
> + ret = gh_rm_dealloc_vmid(ghvm->rm, ghvm->vmid);
> + if (ret)
> + pr_warn("Failed to deallocate vmid: %d\n", ret);
> +
> + put_gh_rm(ghvm->rm);
> + kfree(ghvm);
> +}
> +
> +static __must_check struct gh_vm *gh_vm_alloc(struct gh_rm *rm)
> +{
> + struct gh_vm *ghvm;
> + int vmid;
> +
> + vmid = gh_rm_alloc_vmid(rm, 0);
> + if (vmid < 0)
> + return ERR_PTR(vmid);
> +
> + ghvm = kzalloc(sizeof(*ghvm), GFP_KERNEL);
> + if (!ghvm) {
> + gh_rm_dealloc_vmid(rm, vmid);
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + get_gh_rm(rm);
> +
> + ghvm->vmid = vmid;
> + ghvm->rm = rm;
> +
> + INIT_WORK(&ghvm->free_work, gh_vm_free);
> +
> + return ghvm;
> +}
> +
> +static int gh_vm_release(struct inode *inode, struct file *filp)
> +{
> + struct gh_vm *ghvm = filp->private_data;
> +
> + /* VM will be reset and make RM calls which can interruptible sleep.
> + * Defer to a work so this thread can receive signal.
> + */
> + schedule_work(&ghvm->free_work);
> + return 0;
> +}
> +
> +static const struct file_operations gh_vm_fops = {
> + .release = gh_vm_release,

> + .compat_ioctl = compat_ptr_ioctl,

This line should go with the patch that adds real ioctl

> + .llseek = noop_llseek,
> +};
> +
> +static long gh_dev_ioctl_create_vm(struct gh_rm *rm, unsigned long arg)
Not sure what is the gain of this multiple levels of redirection.

How about

long gh_dev_create_vm(struct gh_rm *rm, unsigned long arg)
{
...
}

and rsc_mgr just call it as part of its ioctl call

static long gh_dev_ioctl(struct file *filp, unsigned int cmd, unsigned
long arg)
{
struct miscdevice *miscdev = filp->private_data;
struct gh_rm *rm = container_of(miscdev, struct gh_rm, miscdev);

switch (cmd) {
case GH_CREATE_VM:
return gh_dev_create_vm(rm, arg);
default:
return -ENOIOCTLCMD;
}
}


> +{
> + struct gh_vm *ghvm;
> + struct file *file;
> + int fd, err;
> +
> + /* arg reserved for future use. */
> + if (arg)
> + return -EINVAL;

The only code path I see here is via GH_CREATE_VM ioctl which obviously
does not take any arguments, so if you are thinking of using the
argument for architecture-specific VM flags. Then this needs to be
properly done by making the ABI aware of this.

As you mentioned zero value arg imply an "unauthenticated VM" type, but
this was not properly encoded in the userspace ABI. Why not make it
future compatible. How about adding arguments to GH_CREATE_VM and pass
the required information correctly.
Note that once the ABI is accepted then you will not be able to change
it, other than adding a new one.

> +
> + ghvm = gh_vm_alloc(rm);
> + if (IS_ERR(ghvm))
> + return PTR_ERR(ghvm);
> +
> + fd = get_unused_fd_flags(O_CLOEXEC);
> + if (fd < 0) {
> + err = fd;
> + goto err_destroy_vm;
> + }
> +
> + file = anon_inode_getfile("gunyah-vm", &gh_vm_fops, ghvm, O_RDWR);
> + if (IS_ERR(file)) {
> + err = PTR_ERR(file);
> + goto err_put_fd;
> + }
> +
> + fd_install(fd, file);
> +
> + return fd;
> +
> +err_put_fd:
> + put_unused_fd(fd);
> +err_destroy_vm:
> + kfree(ghvm);
> + return err;
> +}
> +
> +long gh_dev_vm_mgr_ioctl(struct gh_rm *rm, unsigned int cmd, unsigned long arg)
> +{
> + switch (cmd) {
> + case GH_CREATE_VM:
> + return gh_dev_ioctl_create_vm(rm, arg);
> + default:
> + return -ENOIOCTLCMD;
> + }
> +}
> diff --git a/drivers/virt/gunyah/vm_mgr.h b/drivers/virt/gunyah/vm_mgr.h
> new file mode 100644
> index 000000000000..76954da706e9
> --- /dev/null
> +++ b/drivers/virt/gunyah/vm_mgr.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#ifndef _GH_PRIV_VM_MGR_H
> +#define _GH_PRIV_VM_MGR_H
> +
> +#include <linux/gunyah_rsc_mgr.h>
> +
> +#include <uapi/linux/gunyah.h>
> +
> +long gh_dev_vm_mgr_ioctl(struct gh_rm *rm, unsigned int cmd, unsigned long arg);
> +
> +struct gh_vm {
> + u16 vmid;
> + struct gh_rm *rm;
> +
> + struct work_struct free_work;
> +};
> +
> +#endif
> diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
> new file mode 100644
> index 000000000000..10ba32d2b0a6
> --- /dev/null
> +++ b/include/uapi/linux/gunyah.h
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
> +/*
> + * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#ifndef _UAPI_LINUX_GUNYAH
> +#define _UAPI_LINUX_GUNYAH
> +
> +/*
> + * Userspace interface for /dev/gunyah - gunyah based virtual machine
> + */
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +#define GH_IOCTL_TYPE 'G'
> +
> +/*
> + * ioctls for /dev/gunyah fds:
> + */
> +#define GH_CREATE_VM _IO(GH_IOCTL_TYPE, 0x0) /* Returns a Gunyah VM fd */
Can HLOS forcefully destroy a VM?
If so should we have a corresponding DESTROY IOCTL?

--srini

> +
> +#endif

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