linux-kernel - Re: [RFC PATCH V4 03/17] x86/hyperv: Set Virtual Trust Level in VMBus init message

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Date:   Thu, 13 Apr 2023 11:29:36 +0800
From:   Tianyu Lan <ltykernel@...il.com>
To:     "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        "luto@...nel.org" <luto@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
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        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "jgross@...e.com" <jgross@...e.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
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        <pawan.kumar.gupta@...ux.intel.com>,
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Cc:     "pangupta@....com" <pangupta@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [RFC PATCH V4 03/17] x86/hyperv: Set Virtual Trust Level in VMBus
 init message

On 4/12/2023 10:24 PM, Michael Kelley (LINUX) wrote:
>> +static u8 __init get_vtl(void)
>> +{
>> +	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
>> +	struct hv_get_vp_registers_input *input;
>> +	struct hv_get_vp_registers_output *output;
>> +	u64 vtl = 0;
>> +	u64 ret;
>> +	unsigned long flags;
>> +
>> +	local_irq_save(flags);
>> +	input = *(struct hv_get_vp_registers_input **)this_cpu_ptr(hyperv_pcpu_input_arg);
> The cast to struct hv_get_vp_registers_input isn't needed here.  Just do:
> 
> 	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> 
> I know we have other code that references hyperv_pcpu_input_arg with a more
> complicated code sequence, but it's really not necessary.  At some point, we
> should go back and clean those up, but let's not add any new cases. 😄


Hi Michael:
	Thanks for your review. Yes, agree. I just follow the old coding style 
and will update.

> 
> 
>> +	output = (struct hv_get_vp_registers_output *)input;
>> +	if (!input) {
>> +		local_irq_restore(flags);
>> +		goto done;
>> +	}
>> +
>> +	memset(input, 0, sizeof(*input) + sizeof(input->element[0]));
> Use struct_size() to calculate the size of a structure plus a trailing
> variable size array.
> 
>> +	input->header.partitionid = HV_PARTITION_ID_SELF;
>> +	input->header.vpindex = HV_VP_INDEX_SELF;
>> +	input->header.inputvtl = 0;
>> +	input->element[0].name0 = HV_X64_REGISTER_VSM_VP_STATUS;
>> +
>> +	ret = hv_do_hypercall(control, input, output);
>> +	if (hv_result_success(ret))
>> +		vtl = output->as64.low & HV_X64_VTL_MASK;
>> +	else
>> +		pr_err("Hyper-V: failed to get VTL!");
> Let's include the hypercall status in the failure message.  If a failure ever
> happens, we will really want to know what that status is.  😄
> 

Agree. Will update.

>> rv;
>>   extern bool hv_nested;
>> @@ -58,6 +59,7 @@ extern void * __percpu *hyperv_pcpu_output_arg;
>>   extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
>>   extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
>>   extern bool hv_isolation_type_snp(void);
>> +extern bool hv_isolation_type_en_snp(void);
>