Re: [RFC PATCH V2 02/18] x86/hyperv: Add sev-snp enlightened guest specific config

[Tianyu Lan]

On 12/13/2022 1:56 AM, Michael Kelley (LINUX) wrote:
> > @@ -32,6 +33,7 @@ extern u64 hv_current_partition_id;
> >
> >   extern union hv_ghcb * __percpu *hv_ghcb_pg;
> >
> > +extern bool hv_isolation_type_en_snp(void);
> This file also has a declaration for hv_isolation_type_snp().  I
> think this new declaration is near the beginning of this file so
> that it can be referenced by hv_do_hypercall() and related
> functions in Patch 6 of this series.  So maybe move the
> declaration of hv_isolation_type_snp() up so it is adjacent
> to this one?  It would make sense for the two to be together.

Agree. Will update in the next version.

> > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> > index 831613959a92..2ea4f21c6172 100644
> > --- a/arch/x86/kernel/cpu/mshyperv.c
> > +++ b/arch/x86/kernel/cpu/mshyperv.c
> > @@ -273,6 +273,21 @@ static void __init ms_hyperv_init_platform(void)
> >   	ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
> >   	ms_hyperv.hints    = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
> >
> > +	/*
> > +	 * Add custom configuration for SEV-SNP Enlightened guest
> > +	 */
> > +	if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
> > +		ms_hyperv.features |= HV_ACCESS_FREQUENCY_MSRS;
> > +		ms_hyperv.misc_features |= HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
> > +		ms_hyperv.misc_features &= ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
> > +		ms_hyperv.hints |= HV_DEPRECATING_AEOI_RECOMMENDED;
> > +		ms_hyperv.hints |= HV_X64_APIC_ACCESS_RECOMMENDED;
> > +		ms_hyperv.hints |= HV_X64_CLUSTER_IPI_RECOMMENDED;
> > +	}
> > +
> > +	pr_info("Hyper-V: enlightment features 0x%x, hints 0x%x, misc 0x%x\n",
> > +		ms_hyperv.features, ms_hyperv.hints, ms_hyperv.misc_features);
> > +
> What's the reason for this additional call to pr_info()?  There's a call to pr_info()
> a couple of lines below that displays the same information, and a little bit more.
> It seems like the above call should be deleted, as I think we should try to be as
> consistent as possible in the output.

Sorry for noise. This one should be redundant. Will remove in the next 
version.

> > @@ -328,18 +343,22 @@ static void __init ms_hyperv_init_platform(void)
> >   		ms_hyperv.shared_gpa_boundary =
> >   			BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);
> >
> > -		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);
> >   #ifdef CONFIG_SWIOTLB
> >   			swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
> >   #endif
> >   		}
> > +
> > +		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);
> > +
> Is there a reason for moving this pr_info() down a few lines?  I can't see that the
> intervening code changes any of the settings that are displayed, so it should be
> good in the original location.  Just trying to minimize changes that don't add value ...

Agree. Will keep previous order. Thanks.