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x86/tdx: Introduce wrappers to read and write TD metadata

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The TDG_VM_WR TDCALL is used to ask the TDX module to change some
TD-specific VM configuration. There is currently only one user in the
kernel of this TDCALL leaf.  More will be added shortly.

Refactor to make way for more users of TDG_VM_WR who will need to modify
other TD configuration values.

Add a wrapper for the TDG_VM_RD TDCALL that requests TD-specific
metadata from the TDX module. There are currently no users for
TDG_VM_RD. Mark it as __maybe_unused until the first user appears.

This is preparation for enumeration and enabling optional TD features.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/all/20241104103803.195705-2-kirill.shutemov%40linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2024-11-04 12:38:00 +02:00 • committed by Dave Hansen
parent 59b723cd2a
commit 5081e8fadb
2 changed files with 28 additions and 5 deletions
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32
arch/x86/coco/tdx/tdx.c
View file

@ -78,6 +78,32 @@ static inline void tdcall(u64 fn, struct tdx_module_args *args)
panic("TDCALL %lld failed (Buggy TDX module!)\n", fn);
}
/* Read TD-scoped metadata */
static inline u64 __maybe_unused tdg_vm_rd(u64 field, u64 *value)
{
struct tdx_module_args args = {
.rdx = field,
};
u64 ret;
ret = __tdcall_ret(TDG_VM_RD, &args);
*value = args.r8;
return ret;
}
/* Write TD-scoped metadata */
static inline u64 tdg_vm_wr(u64 field, u64 value, u64 mask)
{
struct tdx_module_args args = {
.rdx = field,
.r8 = value,
.r9 = mask,
};
return __tdcall(TDG_VM_WR, &args);
}
/**
* tdx_mcall_get_report0() - Wrapper to get TDREPORT0 (a.k.a. TDREPORT
* subtype 0) using TDG.MR.REPORT TDCALL.
@ -929,10 +955,6 @@ static void tdx_kexec_finish(void)
void __init tdx_early_init(void)
{
struct tdx_module_args args = {
.rdx = TDCS_NOTIFY_ENABLES,
.r9 = -1ULL,
};
u64 cc_mask;
u32 eax, sig[3];
@ -951,7 +973,7 @@ void __init tdx_early_init(void)
cc_set_mask(cc_mask);
/* Kernel does not use NOTIFY_ENABLES and does not need random #VEs */
tdcall(TDG_VM_WR, &args);
tdg_vm_wr(TDCS_NOTIFY_ENABLES, 0, -1ULL);
/*
* All bits above GPA width are reserved and kernel treats shared bit

1
arch/x86/include/asm/shared/tdx.h
View file

@ -16,6 +16,7 @@
#define TDG_VP_VEINFO_GET 3
#define TDG_MR_REPORT 4
#define TDG_MEM_PAGE_ACCEPT 6
#define TDG_VM_RD 7
#define TDG_VM_WR 8
/* TDCS fields. To be used by TDG.VM.WR and TDG.VM.RD module calls */