Re: [PATCH v9 27/27] virt: gunyah: Add ioeventfd

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

On 20/01/2023 22:46, Elliot Berman wrote:
> Allow userspace to attach an ioeventfd to an mmio address within the guest.
> 
> 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 |  21 +++++
>   drivers/virt/gunyah/Kconfig              |   9 ++
>   drivers/virt/gunyah/Makefile             |   1 +
>   drivers/virt/gunyah/gunyah_ioeventfd.c   | 109 +++++++++++++++++++++++
>   include/uapi/linux/gunyah.h              |  10 +++
>   5 files changed, 150 insertions(+)
>   create mode 100644 drivers/virt/gunyah/gunyah_ioeventfd.c

> +MODULE_LICENSE("GPL");
> diff --git a/include/uapi/linux/gunyah.h b/include/uapi/linux/gunyah.h
> index a947f0317ca9..3cc387f0831a 100644
> --- a/include/uapi/linux/gunyah.h
> +++ b/include/uapi/linux/gunyah.h
> @@ -65,11 +65,21 @@ struct gh_fn_irqfd_arg {
>   	__u32 flags;
>   };
>   
> +struct gh_fn_ioeventfd_arg {
> +	__u64 datamatch;
> +	__u64 addr;        /* legal mmio address */
> +	__u32 len;         /* 1, 2, 4, or 8 bytes; or 0 to ignore length */
> +	__s32 fd;
> +#define GH_IOEVENTFD_DATAMATCH		(1UL << 0)
> +	__u32 flags;

This is not naturally aligned, consider adding a reserved __u32 field to 
be able to make this compatible with both 32 and 64 bit machines.

I see few other uapi structures that suffer exact same issue.

--srini

> +};
> +
>   struct gh_vm_function {
>   	char name[GUNYAH_FUNCTION_NAME_SIZE];
>   	union {
>   		struct gh_fn_vcpu_arg vcpu;
>   		struct gh_fn_irqfd_arg irqfd;
> +		struct gh_fn_ioeventfd_arg ioeventfd;
>   		char data[GUNYAH_FUNCTION_MAX_ARG_SIZE];
>   	};
>   };