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

From: Chenyi Qiang
Date: Thu Aug 08 2024 - 06:32:35 EST




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