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Date:   Thu, 5 Nov 2020 11:10:29 +0800
From:   Shuo A Liu <shuo.a.liu@intel.com>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Yu Wang <yu1.wang@intel.com>,
        Reinette Chatre <reinette.chatre@intel.com>,
        Zhi Wang <zhi.a.wang@intel.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>
Subject: Re: [PATCH v5 06/17] virt: acrn: Introduce VM management interfaces
Message-ID: <20201105031029.GB17702@shuo-intel.sh.intel.com>
References: <20201019061803.13298-1-shuo.a.liu@intel.com>
 <20201019061803.13298-7-shuo.a.liu@intel.com>
 <20201104190235.GA2855400@kroah.com>
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On Wed  4.Nov'20 at 20:02:35 +0100, Greg Kroah-Hartman wrote:
>On Mon, Oct 19, 2020 at 02:17:52PM +0800, shuo.a.liu@intel.com wrote:
>> --- /dev/null
>> +++ b/include/uapi/linux/acrn.h
>> @@ -0,0 +1,56 @@
>> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
>> +/*
>> + * Userspace interface for /dev/acrn_hsm - ACRN Hypervisor Service Module
>> + *
>> + * This file can be used by applications that need to communicate with the HSM
>> + * via the ioctl interface.
>> + */
>> +
>> +#ifndef _UAPI_ACRN_H
>> +#define _UAPI_ACRN_H
>> +
>> +#include <linux/types.h>
>> +
>> +/**
>> + * struct acrn_vm_creation - Info to create a User VM
>> + * @vmid:		User VM ID returned from the hypervisor
>> + * @reserved0:		Reserved
>> + * @vcpu_num:		Number of vCPU in the VM. Return from hypervisor.
>> + * @reserved1:		Reserved
>> + * @uuid:		UUID of the VM. Pass to hypervisor directly.
>> + * @vm_flag:		Flag of the VM creating. Pass to hypervisor directly.
>> + * @ioreq_buf:		Service VM GPA of I/O request buffer. Pass to
>> + *			hypervisor directly.
>> + * @cpu_affinity:	CPU affinity of the VM. Pass to hypervisor directly.
>> + * @reserved2:		Reserved
>
>Reserved and must be 0?  

Not a must.

>What are they reserved for?
>
>Same for all of the reserved fields, why?

Some reserved fields are to map layout in the hypervisor side, others
are for future use.

>
>> + */
>> +struct acrn_vm_creation {
>> +	__u16	vmid;
>> +	__u16	reserved0;
>> +	__u16	vcpu_num;
>> +	__u16	reserved1;
>> +	__u8	uuid[16];
>
>We have a userspace-visable uid structure in include/uapi/uuid.h, why
>not use that?

we just pass the uuid data from user space to hypervisor. So, we can
remove a header dependeny with using raw data format.

Thanks
shuo