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Message-ID: <f7f66da8-7698-4511-900e-5e73af01517b@intel.com>
Date: Fri, 30 Aug 2024 10:02:25 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Kai Huang <kai.huang@...el.com>, dave.hansen@...el.com,
kirill.shutemov@...ux.intel.com, tglx@...utronix.de, bp@...en8.de,
peterz@...radead.org, mingo@...hat.com, hpa@...or.com,
dan.j.williams@...el.com, seanjc@...gle.com, pbonzini@...hat.com
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
rick.p.edgecombe@...el.com, isaku.yamahata@...el.com, chao.gao@...el.com,
binbin.wu@...ux.intel.com
Subject: Re: [PATCH v3 5/8] x86/virt/tdx: Start to track all global metadata
in one structure
On 27/08/24 10:14, Kai Huang wrote:
> The TDX module provides a set of "global metadata fields". They report
Global Metadata Fields
> things like TDX module version, supported features, and fields related
> to create/run TDX guests and so on.
>
> Currently the kernel only reads "TD Memory Region" (TDMR) related fields
> for module initialization. There are immediate needs which require the
> TDX module initialization to read more global metadata including module
> version, supported features and "Convertible Memory Regions" (CMRs).
>
> Also, KVM will need to read more metadata fields to support baseline TDX
> guests. In the longer term, other TDX features like TDX Connect (which
> supports assigning trusted IO devices to TDX guest) may also require
> other kernel components such as pci/vt-d to access global metadata.
>
> To meet all those requirements, the idea is the TDX host core-kernel to
> to provide a centralized, canonical, and read-only structure for the
> global metadata that comes out from the TDX module for all kernel
> components to use.
>
> As the first step, introduce a new 'struct tdx_sys_info' to track all
> global metadata fields.
>
> TDX categories global metadata fields into different "Class"es. E.g.,
"Classes"
> the TDMR related fields are under class "TDMR Info". Instead of making
> 'struct tdx_sys_info' a plain structure to contain all metadata fields,
> organize them in smaller structures based on the "Class".
>
> This allows those metadata fields to be used in finer granularity thus
> makes the code more clear. E.g., the construct_tdmr() can just take the
> structure which contains "TDMR Info" metadata fields.
>
> Add a new function get_tdx_sys_info() as the placeholder to read all
> metadata fields, and call it at the beginning of init_tdx_module(). For
> now it only calls get_tdx_sys_info_tdmr() to read TDMR related fields.
>
> Note there is a functional change: get_tdx_sys_info_tdmr() is moved from
> after build_tdx_memlist() to before it, but it is fine to do so.
>
> Signed-off-by: Kai Huang <kai.huang@...el.com>
Notwithstanding minor cosmetic tweaks:
Reviewed-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>
> v2 -> v3:
> - Split out the part to rename 'struct tdx_tdmr_sysinfo' to 'struct
> tdx_sys_info_tdmr'.
>
>
> ---
> arch/x86/virt/vmx/tdx/tdx.c | 19 ++++++++++++-------
> arch/x86/virt/vmx/tdx/tdx.h | 36 +++++++++++++++++++++++++++++-------
> 2 files changed, 41 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 1cd9035c783f..24eb289c80e8 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -318,6 +318,11 @@ static int get_tdx_sys_info_tdmr(struct tdx_sys_info_tdmr *sysinfo_tdmr)
> return ret;
> }
>
> +static int get_tdx_sys_info(struct tdx_sys_info *sysinfo)
> +{
> + return get_tdx_sys_info_tdmr(&sysinfo->tdmr);
> +}
> +
> /* Calculate the actual TDMR size */
> static int tdmr_size_single(u16 max_reserved_per_tdmr)
> {
> @@ -1090,9 +1095,13 @@ static int init_tdmrs(struct tdmr_info_list *tdmr_list)
>
> static int init_tdx_module(void)
> {
> - struct tdx_sys_info_tdmr sysinfo_tdmr;
> + struct tdx_sys_info sysinfo;
> int ret;
>
> + ret = get_tdx_sys_info(&sysinfo);
> + if (ret)
> + return ret;
> +
> /*
> * To keep things simple, assume that all TDX-protected memory
> * will come from the page allocator. Make sure all pages in the
> @@ -1109,17 +1118,13 @@ static int init_tdx_module(void)
> if (ret)
> goto out_put_tdxmem;
>
> - ret = get_tdx_sys_info_tdmr(&sysinfo_tdmr);
> - if (ret)
> - goto err_free_tdxmem;
> -
> /* Allocate enough space for constructing TDMRs */
> - ret = alloc_tdmr_list(&tdx_tdmr_list, &sysinfo_tdmr);
> + ret = alloc_tdmr_list(&tdx_tdmr_list, &sysinfo.tdmr);
> if (ret)
> goto err_free_tdxmem;
>
> /* Cover all TDX-usable memory regions in TDMRs */
> - ret = construct_tdmrs(&tdx_memlist, &tdx_tdmr_list, &sysinfo_tdmr);
> + ret = construct_tdmrs(&tdx_memlist, &tdx_tdmr_list, &sysinfo.tdmr);
> if (ret)
> goto err_free_tdmrs;
>
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index 8aabd03d8bf5..4cddbb035b9f 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -100,13 +100,6 @@ struct tdx_memblock {
> int nid;
> };
>
> -/* "TDMR info" part of "Global Scope Metadata" for constructing TDMRs */
> -struct tdx_sys_info_tdmr {
> - u16 max_tdmrs;
> - u16 max_reserved_per_tdmr;
> - u16 pamt_entry_size[TDX_PS_NR];
> -};
> -
> /* Warn if kernel has less than TDMR_NR_WARN TDMRs after allocation */
> #define TDMR_NR_WARN 4
>
> @@ -119,4 +112,33 @@ struct tdmr_info_list {
> int max_tdmrs; /* How many 'tdmr_info's are allocated */
> };
>
> +/*
> + * Kernel-defined structures to contain "Global Scope Metadata".
> + *
> + * TDX global metadata fields are categorized by "Class"es. See the
"Classes"
> + * "global_metadata.json" in the "TDX 1.5 ABI Definitions".
> + *
> + * 'struct tdx_sys_info' is the main structure to contain all metadata
> + * used by the kernel. It contains sub-structures with each reflecting
> + * the "Class" in the 'global_metadata.json'.
> + *
> + * Note the structure name may not exactly follow the name of the
> + * "Class" in the TDX spec, but the comment of that structure always
> + * reflect that.
> + *
> + * Also note not all metadata fields in each class are defined, only
> + * those used by the kernel are.
> + */
> +
> +/* Class "TDMR info" */
> +struct tdx_sys_info_tdmr {
> + u16 max_tdmrs;
> + u16 max_reserved_per_tdmr;
> + u16 pamt_entry_size[TDX_PS_NR];
> +};
> +
> +struct tdx_sys_info {
> + struct tdx_sys_info_tdmr tdmr;
> +};
> +
> #endif
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