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

[Tianyu Lan]

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);