Re: [PATCH 1/9] x86/hyperv: Add hv_isolation_type_tdx() to detect TDX guests

[Tianyu Lan <ltykernel@gmail.com>]

On 8/12/2023 6:18 AM, Dexuan Cui wrote:
> No logic change to SNP/VBS guests.
> 
> hv_isolation_type_tdx() will be used to instruct a TDX guest on Hyper-V to
> do some TDX-specific operations, e.g. for a fully enlightened TDX guest
> (i.e. without the paravisor), hv_do_hypercall() should use
> __tdx_hypercall() and such a guest on Hyper-V should handle the Hyper-V
> Event/Message/Monitor pages specially.
> 
> Reviewed-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Dexuan Cui <decui@microsoft.com>

Reviewed-by: Tianyu Lan <tiala@microsoft.com>

> ---
>   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     | 2 ++
>   drivers/hv/hv_common.c             | 6 ++++++
>   include/asm-generic/mshyperv.h     | 1 +
>   6 files changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> index ee08a0cd6da38..d4aafe8b6b50d 100644
> --- a/arch/x86/hyperv/ivm.c
> +++ b/arch/x86/hyperv/ivm.c
> @@ -524,3 +524,12 @@ bool hv_isolation_type_en_snp(void)
>   	return static_branch_unlikely(&isolation_type_en_snp);
>   }
>   
> +DEFINE_STATIC_KEY_FALSE(isolation_type_tdx);
> +/*
> + * hv_isolation_type_tdx - Check if the system runs in an Intel TDX based
> + * isolated VM.
> + */
> +bool hv_isolation_type_tdx(void)
> +{
> +	return static_branch_unlikely(&isolation_type_tdx);
> +}
> diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
> index 4bf0b315b0ce9..2ff26f53cd624 100644
> --- a/arch/x86/include/asm/hyperv-tlfs.h
> +++ b/arch/x86/include/asm/hyperv-tlfs.h
> @@ -169,7 +169,8 @@
>   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 0b0d1eb249d0a..83fc3a79f1557 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -27,6 +27,7 @@ union hv_ghcb;
>   
>   DECLARE_STATIC_KEY_FALSE(isolation_type_snp);
>   DECLARE_STATIC_KEY_FALSE(isolation_type_en_snp);
> +DECLARE_STATIC_KEY_FALSE(isolation_type_tdx);
>   
>   typedef int (*hyperv_fill_flush_list_func)(
>   		struct hv_guest_mapping_flush_list *flush,
> @@ -59,6 +60,8 @@ 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);
>   
> +bool hv_isolation_type_tdx(void);
> +
>   static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
>   {
>   	u64 input_address = input ? virt_to_phys(input) : 0;
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index b7d73f3107c63..a50fd3650ea9b 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -418,6 +418,8 @@ static void __init ms_hyperv_init_platform(void)
>   			static_branch_enable(&isolation_type_en_snp);
>   		} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_SNP) {
>   			static_branch_enable(&isolation_type_snp);
> +		} else if (hv_get_isolation_type() == HV_ISOLATION_TYPE_TDX) {
> +			static_branch_enable(&isolation_type_tdx);
>   		}
>   	}
>   
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index 2d43ba2bc925d..da3307533f4d7 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -521,6 +521,12 @@ bool __weak hv_isolation_type_en_snp(void)
>   }
>   EXPORT_SYMBOL_GPL(hv_isolation_type_en_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))
>   {
>   }
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index efd0d2aedad39..c5e657c3cdf4c 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -66,6 +66,7 @@ extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
>   extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
>   extern bool hv_isolation_type_snp(void);
>   extern bool hv_isolation_type_en_snp(void);
> +extern bool hv_isolation_type_tdx(void);
>   
>   /* Helper functions that provide a consistent pattern for checking Hyper-V hypercall status. */
>   static inline int hv_result(u64 status)