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From:   Michael Kelley <mikelley@microsoft.com>
To:     "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        Tianyu Lan <Tianyu.Lan@microsoft.com>,
        Saruhan Karademir <skarade@microsoft.com>,
        Juan Vazquez <juvazq@microsoft.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Arnd Bergmann <arnd@arndb.de>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Subject: RE: [PATCH v2 1/4] x86/hyperv: Load/save the Isolation Configuration
 leaf
Thread-Topic: [PATCH v2 1/4] x86/hyperv: Load/save the Isolation Configuration
 leaf
Thread-Index: AQHW89pi31QWB+TP3028lS5/+FlxVao9tHIA
Date:   Fri, 29 Jan 2021 00:35:27 +0000
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From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Tuesday, Janu=
ary 26, 2021 3:57 AM
>=20
> If bit 22 of Group B Features is set, the guest has access to the
> Isolation Configuration CPUID leaf.  On x86, the first four bits
> of EAX in this leaf provide the isolation type of the partition;
> we entail three isolation types: 'SNP' (hardware-based isolation),
> 'VBS' (software-based isolation), and 'NONE' (no isolation).
>=20
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: x86@kernel.org
> Cc: linux-arch@vger.kernel.org
> ---
>  arch/x86/hyperv/hv_init.c          | 15 +++++++++++++++
>  arch/x86/include/asm/hyperv-tlfs.h | 15 +++++++++++++++
>  arch/x86/kernel/cpu/mshyperv.c     |  9 +++++++++
>  include/asm-generic/hyperv-tlfs.h  |  1 +
>  include/asm-generic/mshyperv.h     |  5 +++++
>  5 files changed, 45 insertions(+)
>=20
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index e04d90af4c27c..dc94e95c57b98 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -10,6 +10,7 @@
>  #include <linux/acpi.h>
>  #include <linux/efi.h>
>  #include <linux/types.h>
> +#include <linux/bitfield.h>
>  #include <asm/apic.h>
>  #include <asm/desc.h>
>  #include <asm/hypervisor.h>
> @@ -528,3 +529,17 @@ bool hv_is_hibernation_supported(void)
>  	return acpi_sleep_state_supported(ACPI_STATE_S4);
>  }
>  EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
> +
> +enum hv_isolation_type hv_get_isolation_type(void)
> +{
> +	if (!(ms_hyperv.hypercalls_features & HV_ISOLATION))
> +		return HV_ISOLATION_TYPE_NONE;
> +	return FIELD_GET(HV_ISOLATION_TYPE, ms_hyperv.isolation_config_b);
> +}
> +EXPORT_SYMBOL_GPL(hv_get_isolation_type);
> +
> +bool hv_is_isolation_supported(void)
> +{
> +	return hv_get_isolation_type() !=3D HV_ISOLATION_TYPE_NONE;
> +}
> +EXPORT_SYMBOL_GPL(hv_is_isolation_supported);
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hy=
perv-tlfs.h
> index 6bf42aed387e3..6aed936e5e962 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -22,6 +22,7 @@
>  #define HYPERV_CPUID_ENLIGHTMENT_INFO		0x40000004
>  #define HYPERV_CPUID_IMPLEMENT_LIMITS		0x40000005
>  #define HYPERV_CPUID_NESTED_FEATURES		0x4000000A
> +#define HYPERV_CPUID_ISOLATION_CONFIG		0x4000000C
>=20
>  #define HYPERV_CPUID_VIRT_STACK_INTERFACE	0x40000081
>  #define HYPERV_VS_INTERFACE_EAX_SIGNATURE	0x31235356  /* "VS#1" */
> @@ -122,6 +123,20 @@
>  #define HV_X64_NESTED_GUEST_MAPPING_FLUSH		BIT(18)
>  #define HV_X64_NESTED_MSR_BITMAP			BIT(19)
>=20
> +/* HYPERV_CPUID_ISOLATION_CONFIG.EAX bits. */
> +#define HV_PARAVISOR_PRESENT				BIT(0)
> +
> +/* HYPERV_CPUID_ISOLATION_CONFIG.EBX bits. */
> +#define HV_ISOLATION_TYPE				GENMASK(3, 0)
> +#define HV_SHARED_GPA_BOUNDARY_ACTIVE			BIT(5)
> +#define HV_SHARED_GPA_BOUNDARY_BITS			GENMASK(11, 6)
> +
> +enum hv_isolation_type {
> +	HV_ISOLATION_TYPE_NONE	=3D 0,
> +	HV_ISOLATION_TYPE_VBS	=3D 1,
> +	HV_ISOLATION_TYPE_SNP	=3D 2
> +};
> +
>  /* Hyper-V specific model specific registers (MSRs) */
>=20
>  /* MSR used to identify the guest OS. */
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyper=
v.c
> index f628e3dc150f3..0d4aaf6694d01 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -225,6 +225,7 @@ static void __init ms_hyperv_init_platform(void)
>  	 * Extract the features and hints
>  	 */
>  	ms_hyperv.features =3D cpuid_eax(HYPERV_CPUID_FEATURES);
> +	ms_hyperv.hypercalls_features =3D cpuid_ebx(HYPERV_CPUID_FEATURES);
>  	ms_hyperv.misc_features =3D cpuid_edx(HYPERV_CPUID_FEATURES);
>  	ms_hyperv.hints    =3D cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
>=20
> @@ -259,6 +260,14 @@ static void __init ms_hyperv_init_platform(void)
>  		x86_platform.calibrate_cpu =3D hv_get_tsc_khz;
>  	}
>=20
> +	if (ms_hyperv.hypercalls_features & HV_ISOLATION) {
> +		ms_hyperv.isolation_config_a =3D cpuid_eax(HYPERV_CPUID_ISOLATION_CONF=
IG);
> +		ms_hyperv.isolation_config_b =3D cpuid_ebx(HYPERV_CPUID_ISOLATION_CONF=
IG);
> +
> +		pr_info("Hyper-V: Isolation Config: GroupA 0x%x, GroupB 0x%x\n",

Nit:  Let's put a space after the word "Group", so that we have
"Hyper-V: Isolation Config: Group A 0x%x, Group B 0x%x\n".

> +			ms_hyperv.isolation_config_a, ms_hyperv.isolation_config_b);
> +	}
> +
>  	if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) {
>  		ms_hyperv.nested_features =3D
>  			cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
> diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hype=
rv-tlfs.h
> index e73a11850055c..20d3cd9502043 100644
> --- a/include/asm-generic/hyperv-tlfs.h
> +++ b/include/asm-generic/hyperv-tlfs.h
> @@ -89,6 +89,7 @@
>  #define HV_ACCESS_STATS				BIT(8)
>  #define HV_DEBUGGING				BIT(11)
>  #define HV_CPU_POWER_MANAGEMENT			BIT(12)
> +#define HV_ISOLATION				BIT(22)
>=20
>=20
>  /*
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyper=
v.h
> index c57799684170c..c7f75b36f88ba 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -27,11 +27,14 @@
>=20
>  struct ms_hyperv_info {
>  	u32 features;
> +	u32 hypercalls_features;

There was an offline conversation about renaming some of these fields so
they more obviously map to the Hyper-V TLFS while also being architecture
neutral.  Toward that end, I'd suggest the "hypercalls_features" field shou=
ld be
named "features_b".  This would align with the offline discussion, and matc=
hes
what you've done with "isolation_config_a"  and similar below (which is goo=
d).

>  	u32 misc_features;
>  	u32 hints;
>  	u32 nested_features;
>  	u32 max_vp_index;
>  	u32 max_lp_index;
> +	u32 isolation_config_a;
> +	u32 isolation_config_b;
>  };
>  extern struct ms_hyperv_info ms_hyperv;
>=20
> @@ -169,6 +172,8 @@ void hyperv_report_panic(struct pt_regs *regs, long e=
rr, bool
> in_die);
>  void hyperv_report_panic_msg(phys_addr_t pa, size_t size);
>  bool hv_is_hyperv_initialized(void);
>  bool hv_is_hibernation_supported(void);
> +enum hv_isolation_type hv_get_isolation_type(void);
> +bool hv_is_isolation_supported(void);
>  void hyperv_cleanup(void);
>  #else /* CONFIG_HYPERV */
>  static inline bool hv_is_hyperv_initialized(void) { return false; }
> --
> 2.25.1