Commit 5081e8fa authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Dave Hansen
Browse files

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



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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarKai Huang <kai.huang@intel.com>
Reviewed-by: default avatarKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/all/20241104103803.195705-2-kirill.shutemov%40linux.intel.com
parent 59b723cd

arch/x86/coco/tdx/tdx.c

+27 −5
Original line number Diff line number Diff line
@@ -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

arch/x86/include/asm/shared/tdx.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */