Re: [PATCH v2 08/10] x86/virt/tdx: Print TDX module basic information

[Chenyi Qiang]

On 7/17/2024 11:40 AM, Kai Huang wrote:
> Currently the kernel doesn't print any information regarding the TDX
> module itself, e.g. module version.  In practice such information is
> useful, especially to the developers.
> 
> For instance, there are a couple of use cases for dumping module basic
> information:
> 
> 1) When something goes wrong around using TDX, the information like TDX
>    module version, supported features etc could be helpful [1][2].
> 
> 2) For Linux, when the user wants to update the TDX module, one needs to
>    replace the old module in a specific location in the EFI partition
>    with the new one so that after reboot the BIOS can load it.  However,
>    after kernel boots, currently the user has no way to verify it is
>    indeed the new module that gets loaded and initialized (e.g., error
>    could happen when replacing the old module).  With the module version
>    dumped the user can verify this easily.
> 
> So dump the basic TDX module information:
> 
>  - TDX module version, and the build date.
>  - TDX module type: Debug or Production.
>  - TDX_FEATURES0: Supported TDX features.
> 
> And dump the information right after reading global metadata, so that
> this information is printed no matter whether module initialization
> fails or not.
> 
> The actual dmesg will look like:
> 
>   virt/tdx: Initializing TDX module: 1.5.00.00.0481 (build_date 20230323, Production module), TDX_FEATURES0 0xfbf
> 
> Link: https://lore.kernel.org/lkml/e2d844ad-182a-4fc0-a06a-d609c9cbef74@xxxxxxxx/T/#m352829aedf6680d4628c7e40dc40b332eda93355 [1]
> Link: https://lore.kernel.org/lkml/e2d844ad-182a-4fc0-a06a-d609c9cbef74@xxxxxxxx/T/#m351ebcbc006d2e5bc3e7650206a087cb2708d451 [2]
> Signed-off-by: Kai Huang <kai.huang@xxxxxxxxx>
> ---
> 
> v1 -> v2 (Nikolay):
>  - Change the format to dump TDX basic info.
>  - Slightly improve changelog.
> 
> ---
>  arch/x86/virt/vmx/tdx/tdx.c | 64 +++++++++++++++++++++++++++++++++++++
>  arch/x86/virt/vmx/tdx/tdx.h | 33 ++++++++++++++++++-
>  2 files changed, 96 insertions(+), 1 deletion(-)
> 

[...]

> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index b5eb7c35f1dc..861ddf2c2e88 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -31,6 +31,15 @@
>   *
>   * See the "global_metadata.json" in the "TDX 1.5 ABI definitions".
>   */
> +#define MD_FIELD_ID_SYS_ATTRIBUTES		0x0A00000200000000ULL
> +#define MD_FIELD_ID_TDX_FEATURES0		0x0A00000300000008ULL
> +#define MD_FIELD_ID_BUILD_DATE			0x8800000200000001ULL
> +#define MD_FIELD_ID_BUILD_NUM			0x8800000100000002ULL
> +#define MD_FIELD_ID_MINOR_VERSION		0x0800000100000003ULL
> +#define MD_FIELD_ID_MAJOR_VERSION		0x0800000100000004ULL
> +#define MD_FIELD_ID_UPDATE_VERSION		0x0800000100000005ULL
> +#define MD_FIELD_ID_INTERNAL_VERSION		0x0800000100000006ULL
> +
>  #define MD_FIELD_ID_MAX_TDMRS			0x9100000100000008ULL
>  #define MD_FIELD_ID_MAX_RESERVED_PER_TDMR	0x9100000100000009ULL
>  #define MD_FIELD_ID_PAMT_4K_ENTRY_SIZE		0x9100000100000010ULL
> @@ -124,8 +133,28 @@ struct tdmr_info_list {
>   *
>   * Note not all metadata fields in each class are defined, only those
>   * used by the kernel are.
> + *
> + * Also note the "bit definitions" are architectural.
>   */
>  
> +/* Class "TDX Module Info" */
> +struct tdx_sysinfo_module_info {
> +	u32 sys_attributes;
> +	u64 tdx_features0;
> +};
> +
> +#define TDX_SYS_ATTR_DEBUG_MODULE	0x1

One minor issue, TDX_SYS_ATTR_DEBUG_MODULE is indicated by bit 31 of
sys_attributes.

> +
> +/* Class "TDX Module Version" */
> +struct tdx_sysinfo_module_version {
> +	u16 major;
> +	u16 minor;
> +	u16 update;
> +	u16 internal;
> +	u16 build_num;
> +	u32 build_date;
> +};
> +
>  /* Class "TDMR Info" */
>  struct tdx_sysinfo_tdmr_info {
>  	u16 max_tdmrs;
> @@ -134,7 +163,9 @@ struct tdx_sysinfo_tdmr_info {
>  };
>  
>  struct tdx_sysinfo {
> -	struct tdx_sysinfo_tdmr_info tdmr_info;
> +	struct tdx_sysinfo_module_info		module_info;
> +	struct tdx_sysinfo_module_version	module_version;
> +	struct tdx_sysinfo_tdmr_info		tdmr_info;
>  };
>  
>  #endif