linux-kernel - Re: [PATCH v2 07/17] virt: acrn: Introduce an ioctl to set vCPU registers state

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Date:   Fri, 4 Sep 2020 12:39:53 +0800
From:   "Liu, Shuo A" <shuo.a.liu@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        "H . Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Yu Wang <yu1.wang@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>
Subject: Re: [PATCH v2 07/17] virt: acrn: Introduce an ioctl to set vCPU
 registers state

Hi Greg,

On 9/3/2020 21:03, Greg Kroah-Hartman wrote:
> On Thu, Sep 03, 2020 at 08:41:51PM +0800, shuo.a.liu@...el.com wrote:
>> From: Shuo Liu <shuo.a.liu@...el.com>
>>
>> A virtual CPU of User VM has different context due to the different
>> registers state. ACRN userspace needs to set the virtual CPU
>> registers state (e.g. giving a initial registers state to a virtual
>> BSP of a User VM).
>>
>> HSM provides an ioctl ACRN_IOCTL_SET_VCPU_REGS to do the virtual CPU
>> registers state setting. The ioctl passes the registers state from ACRN
>> userspace to the hypervisor directly.
>>
>> Signed-off-by: Shuo Liu <shuo.a.liu@...el.com>
>> Reviewed-by: Zhi Wang <zhi.a.wang@...el.com>
>> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
>> Cc: Zhi Wang <zhi.a.wang@...el.com>
>> Cc: Zhenyu Wang <zhenyuw@...ux.intel.com>
>> Cc: Yu Wang <yu1.wang@...el.com>
>> Cc: Reinette Chatre <reinette.chatre@...el.com>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> ---
>>  drivers/virt/acrn/hsm.c       | 14 +++++++
>>  drivers/virt/acrn/hypercall.h | 13 +++++++
>>  include/uapi/linux/acrn.h     | 71 +++++++++++++++++++++++++++++++++++
>>  3 files changed, 98 insertions(+)
>>
>> diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
>> index 6ec6aa9053d3..13df76d0206e 100644
>> --- a/drivers/virt/acrn/hsm.c
>> +++ b/drivers/virt/acrn/hsm.c
>> @@ -12,6 +12,7 @@
>>  #define pr_fmt(fmt) "acrn: " fmt
>>  #define dev_fmt(fmt) "acrn: " fmt
>>  
>> +#include <linux/io.h>
>>  #include <linux/miscdevice.h>
>>  #include <linux/mm.h>
>>  #include <linux/module.h>
>> @@ -49,6 +50,7 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
>>  {
>>  	struct acrn_vm *vm = filp->private_data;
>>  	struct acrn_vm_creation *vm_param;
>> +	struct acrn_vcpu_regs *cpu_regs;
>>  	int ret = 0;
>>  
>>  	if (vm->vmid == ACRN_INVALID_VMID && cmd != ACRN_IOCTL_CREATE_VM) {
>> @@ -96,6 +98,18 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
>>  	case ACRN_IOCTL_DESTROY_VM:
>>  		ret = acrn_vm_destroy(vm);
>>  		break;
>> +	case ACRN_IOCTL_SET_VCPU_REGS:
>> +		cpu_regs = memdup_user((void __user *)ioctl_param,
>> +				       sizeof(struct acrn_vcpu_regs));
>> +		if (IS_ERR(cpu_regs))
>> +			return PTR_ERR(cpu_regs);
>> +
>> +		ret = hcall_set_vcpu_regs(vm->vmid, virt_to_phys(cpu_regs));
> 
> No sanity checking of any arguments?

The HSM driver has limited VM status maintenance so it doesn't have full
ability to do the sanity checking.

> 
> Wow, fuzzers are going to have a fun time with your hypervisor, good
> luck!  :)

The hypervisor has some sanity checking. :)

Thanks
shuo