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Subject: RE: [RFC PATCH V2 02/18] x86/hyperv: Add sev-snp enlightened guest
 specific config
Thread-Topic: [RFC PATCH V2 02/18] x86/hyperv: Add sev-snp enlightened guest
 specific config
Thread-Index: AQHY+8mZf+1Iyx0OH0GDW+MmqmAne65qpz9g
Date:   Mon, 12 Dec 2022 17:56:18 +0000
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 <20221119034633.1728632-3-ltykernel@gmail.com>
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From: Tianyu Lan <ltykernel@gmail.com> Sent: Friday, November 18, 2022 7:46=
 PM
>=20
> Introduce static key isolation_type_en_snp for enlightened
> guest check and add some specific options in ms_hyperv_init_
> platform().
>=20
> Signed-off-by: Tianyu Lan <tiala@microsoft.com>
> ---
>  arch/x86/hyperv/ivm.c           | 12 +++++++++++-
>  arch/x86/include/asm/mshyperv.h |  2 ++
>  arch/x86/kernel/cpu/mshyperv.c  | 29 ++++++++++++++++++++++++-----
>  drivers/hv/hv_common.c          |  7 +++++++
>  4 files changed, 44 insertions(+), 6 deletions(-)
>=20
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 1dbcbd9da74d..e9c30dad3419 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -259,10 +259,20 @@ bool hv_is_isolation_supported(void)
>  }
>=20
>  DEFINE_STATIC_KEY_FALSE(isolation_type_snp);
> +DEFINE_STATIC_KEY_FALSE(isolation_type_en_snp);
> +
> +/*
> + * hv_isolation_type_en_snp - Check system runs in the AMD SEV-SNP based
> + * isolation enlightened VM.
> + */
> +bool hv_isolation_type_en_snp(void)
> +{
> +	return static_branch_unlikely(&isolation_type_en_snp);
> +}
>=20
>  /*
>   * hv_isolation_type_snp - Check system runs in the AMD SEV-SNP based
> - * isolation VM.
> + * isolation VM with vTOM support.
>   */
>  bool hv_isolation_type_snp(void)
>  {
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyp=
erv.h
> index 61f0c206bff0..9b8c3f638845 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -14,6 +14,7 @@
>  union hv_ghcb;
>=20
>  DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
> +DECLARE_STATIC_KEY_FALSE(isolation_type_en_snp);
>=20
>  typedef int (*hyperv_fill_flush_list_func)(
>  		struct hv_guest_mapping_flush_list *flush,
> @@ -32,6 +33,7 @@ extern u64 hv_current_partition_id;
>=20
>  extern union hv_ghcb * __percpu *hv_ghcb_pg;
>=20
> +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.

>  int hv_call_deposit_pages(int node, u64 partition_id, u32 num_pages);
>  int hv_call_add_logical_proc(int node, u32 lp_index, u32 acpi_id);
>  int hv_call_create_vp(int node, u64 partition_id, u32 vp_index, u32 flag=
s);
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyper=
v.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 =3D cpuid_edx(HYPERV_CPUID_FEATURES);
>  	ms_hyperv.hints    =3D cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
>=20
> +	/*
> +	 * Add custom configuration for SEV-SNP Enlightened guest
> +	 */
> +	if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) {
> +		ms_hyperv.features |=3D HV_ACCESS_FREQUENCY_MSRS;
> +		ms_hyperv.misc_features |=3D HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
> +		ms_hyperv.misc_features &=3D ~HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
> +		ms_hyperv.hints |=3D HV_DEPRECATING_AEOI_RECOMMENDED;
> +		ms_hyperv.hints |=3D HV_X64_APIC_ACCESS_RECOMMENDED;
> +		ms_hyperv.hints |=3D 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 bi=
t 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.

>  	hv_max_functions_eax =3D cpuid_eax(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTION=
S);
>=20
>  	pr_info("Hyper-V: privilege flags low 0x%x, high 0x%x, hints 0x%x, misc=
 0x%x\n",
> @@ -328,18 +343,22 @@ static void __init ms_hyperv_init_platform(void)
>  		ms_hyperv.shared_gpa_boundary =3D
>  			BIT_ULL(ms_hyperv.shared_gpa_boundary_bits);
>=20
> -		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() =3D=3D 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() =3D=3D HV_ISOLATION_TYPE_SNP) {
>  			static_branch_enable(&isolation_type_snp);
>  #ifdef CONFIG_SWIOTLB
>  			swiotlb_unencrypted_base =3D 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 shou=
ld be
good in the original location.  Just trying to minimize changes that don't =
add value ...

>  		/* Isolation VMs are unenlightened SEV-based VMs, thus this check: */
>  		if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
> -			if (hv_get_isolation_type() !=3D HV_ISOLATION_TYPE_NONE)
> +			if (hv_get_isolation_type() !=3D HV_ISOLATION_TYPE_NONE
> +			    && !cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
>  				cc_set_vendor(CC_VENDOR_HYPERV);
>  		}
>  	}
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index ae68298c0dca..2c6602571c47 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -268,6 +268,13 @@ bool __weak hv_isolation_type_snp(void)
>  }
>  EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
>=20
> +bool __weak hv_isolation_type_en_snp(void)
> +{
> +	return false;
> +}
> +EXPORT_SYMBOL_GPL(hv_isolation_type_en_snp);
> +
> +

Nit: One blank line is sufficient.  Don't need to add two.

>  void __weak hv_setup_vmbus_handler(void (*handler)(void))
>  {
>  }
> --
> 2.25.1