Re: [PATCH v2 3/6] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests

[Sathyanarayanan Kuppuswamy]

Hi,

On 12/6/22 4:33 PM, Dexuan Cui wrote:
> No logic change to SNP/VBS guests.
> 
> hv_isolation_type_tdx() wil be used to instruct a TDX guest on Hyper-V to
> do some TDX-specific operations, e.g. hv_do_hypercall() should use
> __tdx_hypercall(), and a TDX guest on Hyper-V should handle the Hyper-V
> Event/Message/Monitor pages specially.
> 
> Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
> 
> ---

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

> 
> Changes in v2:
>   Added "#ifdef CONFIG_INTEL_TDX_GUEST and #endif" for
>     hv_isolation_type_tdx() in arch/x86/hyperv/ivm.c.
> 
>     Simplified the changes in ms_hyperv_init_platform().
> 
>  arch/x86/hyperv/ivm.c              | 9 +++++++++
>  arch/x86/include/asm/hyperv-tlfs.h | 3 ++-
>  arch/x86/include/asm/mshyperv.h    | 3 +++
>  arch/x86/kernel/cpu/mshyperv.c     | 7 ++++++-
>  drivers/hv/hv_common.c             | 6 ++++++
>  5 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index 1dbcbd9da74d..13ccb52eecd7 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -269,6 +269,15 @@ bool hv_isolation_type_snp(void)
>  	return static_branch_unlikely(&isolation_type_snp);
>  }
>  
> +#ifdef CONFIG_INTEL_TDX_GUEST
> +DEFINE_STATIC_KEY_FALSE(isolation_type_tdx);
> +
> +bool hv_isolation_type_tdx(void)
> +{
> +	return static_branch_unlikely(&isolation_type_tdx);
> +}
> +#endif
> +
>  /*
>   * hv_mark_gpa_visibility - Set pages visible to host via hvcall.
>   *
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 6d9368ea3701..6c0a04d078f5 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -161,7 +161,8 @@
>  enum hv_isolation_type {
>  	HV_ISOLATION_TYPE_NONE	= 0,
>  	HV_ISOLATION_TYPE_VBS	= 1,
> -	HV_ISOLATION_TYPE_SNP	= 2
> +	HV_ISOLATION_TYPE_SNP	= 2,
> +	HV_ISOLATION_TYPE_TDX	= 3
>  };
>  
>  /* Hyper-V specific model specific registers (MSRs) */
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 61f0c206bff0..8a2cafec4675 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -14,6 +14,7 @@
>  union hv_ghcb;
>  
>  DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
> +DECLARE_STATIC_KEY_FALSE(isolation_type_tdx);
>  
>  typedef int (*hyperv_fill_flush_list_func)(
>  		struct hv_guest_mapping_flush_list *flush,
> @@ -32,6 +33,8 @@ extern u64 hv_current_partition_id;
>  
>  extern union hv_ghcb * __percpu *hv_ghcb_pg;
>  
> +extern bool hv_isolation_type_tdx(void);
> +
>  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 flags);
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index 46668e255421..941372449ff2 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -339,9 +339,14 @@ static void __init ms_hyperv_init_platform(void)
>  		}
>  		/* Isolation VMs are unenlightened SEV-based VMs, thus this check: */
>  		if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {
> -			if (hv_get_isolation_type() != HV_ISOLATION_TYPE_NONE)
> +			if (hv_get_isolation_type() == HV_ISOLATION_TYPE_VBS ||
> +			    hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP)
>  				cc_set_vendor(CC_VENDOR_HYPERV);
>  		}
> +
> +		if (IS_ENABLED(CONFIG_INTEL_TDX_GUEST) &&
> +		    hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX)
> +			static_branch_enable(&isolation_type_tdx);
>  	}
>  
>  	if (hv_max_functions_eax >= HYPERV_CPUID_NESTED_FEATURES) {
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index ae68298c0dca..a9a03ab04b97 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -268,6 +268,12 @@ bool __weak hv_isolation_type_snp(void)
>  }
>  EXPORT_SYMBOL_GPL(hv_isolation_type_snp);
>  
> +bool __weak hv_isolation_type_tdx(void)
> +{
> +	return false;
> +}
> +EXPORT_SYMBOL_GPL(hv_isolation_type_tdx);
> +
>  void __weak hv_setup_vmbus_handler(void (*handler)(void))
>  {
>  }

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer