From: Andrea Parri (Microsoft) <parri.and...@gmail.com> Sent: Tuesday, January
26, 2021 3:57 AM
>
> 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).
>
> Signed-off-by: Andrea Parri (Microsoft) <parri.and...@gmail.com>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Borislav Petkov <b...@alien8.de>
> Cc: "H. Peter Anvin" <h...@zytor.com>
> Cc: Arnd Bergmann <a...@arndb.de>
> Cc: x...@kernel.org
> Cc: linux-a...@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(+)
>
> 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() != 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/hyperv-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
>
> #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)
>
> +/* 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 = 0,
> + HV_ISOLATION_TYPE_VBS = 1,
> + HV_ISOLATION_TYPE_SNP = 2
> +};
> +
> /* Hyper-V specific model specific registers (MSRs) */
>
> /* MSR used to identify the guest OS. */
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.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 = cpuid_eax(HYPERV_CPUID_FEATURES);
> + ms_hyperv.hypercalls_features = cpuid_ebx(HYPERV_CPUID_FEATURES);
> ms_hyperv.misc_features = cpuid_edx(HYPERV_CPUID_FEATURES);
> ms_hyperv.hints = cpuid_eax(HYPERV_CPUID_ENLIGHTMENT_INFO);
>
> @@ -259,6 +260,14 @@ static void __init ms_hyperv_init_platform(void)
> x86_platform.calibrate_cpu = hv_get_tsc_khz;
> }
>
> + if (ms_hyperv.hypercalls_features & HV_ISOLATION) {
> + ms_hyperv.isolation_config_a =
> cpuid_eax(HYPERV_CPUID_ISOLATION_CONFIG);
> + ms_hyperv.isolation_config_b =
> cpuid_ebx(HYPERV_CPUID_ISOLATION_CONFIG);
> +
> + 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 =
> cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
> diff --git a/include/asm-generic/hyperv-tlfs.h
> b/include/asm-generic/hyperv-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)
>
>
> /*
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index c57799684170c..c7f75b36f88ba 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -27,11 +27,14 @@
>
> 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 should be
named "features_b". This would align with the offline discussion, and matches
what you've done with "isolation_config_a" and similar below (which is good).
> 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;
>
> @@ -169,6 +172,8 @@ void hyperv_report_panic(struct pt_regs *regs, long err,
> 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
