Re: [PATCH v9 24/27] virt: gunyah: Add proxy-scheduled vCPUs

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

On 20/01/2023 22:46, Elliot Berman wrote:
> Gunyah allows host virtual machines to schedule guest virtual machines
> and handle their MMIO accesses. vCPUs are presented to the host as a
> Gunyah resource and represented to userspace as a Gunyah VM function.
> 
> Creating the vcpu VM function will create a file descriptor that:
>   - can run an ioctl: GH_VCPU_RUN to schedule the guest vCPU until the
>     next interrupt occurs on the host or when the guest vCPU can no
>     longer be run.
>   - can be mmap'd to share a gh_vcpu_run structure which can look up the
>     reason why GH_VCPU_RUN returned and provide return values for MMIO
>     access.
> 
> 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>
> ---
>   Documentation/virt/gunyah/vm-manager.rst |  30 +-
>   arch/arm64/gunyah/gunyah_hypercall.c     |  28 ++
>   drivers/virt/gunyah/Kconfig              |  11 +
>   drivers/virt/gunyah/Makefile             |   2 +
>   drivers/virt/gunyah/gunyah_vcpu.c        | 358 +++++++++++++++++++++++
>   drivers/virt/gunyah/vm_mgr.c             |  25 ++
>   drivers/virt/gunyah/vm_mgr.h             |   1 +
>   include/linux/gunyah.h                   |   7 +
>   include/uapi/linux/gunyah.h              |  30 ++
>   9 files changed, 490 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/virt/gunyah/gunyah_vcpu.c
> 
...


> diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
> index ec8da6fde045..b4afb11f538a 100644
> --- a/include/uapi/linux/gunyah.h
> +++ b/include/uapi/linux/gunyah.h
> @@ -53,9 +53,14 @@ struct gh_vm_dtb_config {
>   #define GUNYAH_FUNCTION_NAME_SIZE		32
>   #define GUNYAH_FUNCTION_MAX_ARG_SIZE		1024
>   
> +struct gh_fn_vcpu_arg {
> +	__u32 vcpu_id;
> +};
> +
>   struct gh_vm_function {
>   	char name[GUNYAH_FUNCTION_NAME_SIZE];
>   	union {
> +		struct gh_device_vcpu_arg vcpu;
>   		char data[GUNYAH_FUNCTION_MAX_ARG_SIZE];
>   	};
>   };
> @@ -63,4 +68,29 @@ struct gh_vm_function {
>   #define GH_VM_ADD_FUNCTION	_IOW(GH_IOCTL_TYPE, 0x4, struct gh_vm_function)
>   #define GH_VM_REMOVE_FUNCTION	_IOW(GH_IOCTL_TYPE, 0x7, struct gh_vm_function)
>   
> +/* for GH_VCPU_RUN, returned by mmap(vcpu_fd, offset=0) */
> +struct gh_vcpu_run {
this looks unused, I dont see any reference to this.

> +	/* in */
> +	__u8 immediate_exit;
> +	__u8 padding1[7];
> +
> +	/* out */
> +#define GH_VM_EXIT_UNKNOWN            0
> +#define GH_VM_EXIT_MMIO               1
> +	__u32 exit_reason;

If this is ment to go in any of the ioctl arguments then this suffers 
same issue of padding.

> +
> +	union {
> +		/* GH_VM_EXIT_MMIO */
> +		struct {
> +			__u64 phys_addr;
> +			__u8  data[8];
> +			__u32 len;
> +			__u8  is_write;
> +		} mmio;
> +	};
> +};
> +
> +#define GH_VCPU_RUN		_IO(GH_IOCTL_TYPE, 0x5)
> +#define GH_VCPU_MMAP_SIZE	_IO(GH_IOCTL_TYPE, 0x6)
> +
>   #endif