Re: [PATCH 1/9] x86/hyperv: Add sev-snp enlightened guest static key

[Tianyu Lan]

On 6/5/2023 8:09 PM, Vitaly Kuznetsov wrote:
> > --- a/arch/x86/kernel/cpu/mshyperv.c
> > +++ b/arch/x86/kernel/cpu/mshyperv.c
> > @@ -402,8 +402,12 @@ static void __init ms_hyperv_init_platform(void)
> >   		pr_info("Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n",
> >   			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
> >   
> > -		if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
> > +
> > +		if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
> > +			static_branch_enable(&isolation_type_en_snp);
> > +		} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
> >   			static_branch_enable(&isolation_type_snp);
> Nitpick: In case 'isolation_type_snp' and 'isolation_type_en_snp' are
> mutually exclusive, I'd suggest we rename the former: it is quite
> un-intuitive that for an enlightened SNP guest '&isolation_type_snp' is
> NOT enabled. E.g. we can use
>
> 'isol_type_snp_paravisor'
> and
> 'isol_type_snp_enlightened'
>
> (I also don't like 'isolation_type_en_snp' name as 'en' normally stands
> for 'enabled')

Hi Vitaly:
	Thanks for your review. Agree. Will rename them.

> > --- a/include/asm-generic/mshyperv.h
> > +++ b/include/asm-generic/mshyperv.h
> > @@ -36,15 +36,21 @@ struct ms_hyperv_info {
> >   	u32 nested_features;
> >   	u32 max_vp_index;
> >   	u32 max_lp_index;
> > -	u32 isolation_config_a;
> > +	union {
> > +		u32 isolation_config_a;
> > +		struct {
> > +			u32 paravisor_present : 1;
> > +			u32 reserved1 : 31;
> > +		};
> > +	};
> >   	union {
> >   		u32 isolation_config_b;
> >   		struct {
> >   			u32 cvm_type : 4;
> > -			u32 reserved1 : 1;
> > +			u32 reserved2 : 1;
> >   			u32 shared_gpa_boundary_active : 1;
> >   			u32 shared_gpa_boundary_bits : 6;
> > -			u32 reserved2 : 20;
> > +			u32 reserved3 : 20;
> Maybe use 'reserved_a1', 'reserved_b1', 'reserved_b2',... to avoid the
> need to rename in the future when more bits from isolation_config_a get
> used?

Good suggestion. will update.