linux/arch/x86/boot/cpuflags.h
Kuppuswamy Sathyanarayanan 4b05f81504 x86/tdx: Detect TDX at early kernel decompression time
The early decompression code does port I/O for its console output. But,
handling the decompression-time port I/O demands a different approach
from normal runtime because the IDT required to support #VE based port
I/O emulation is not yet set up. Paravirtualizing I/O calls during
the decompression step is acceptable because the decompression code
doesn't have a lot of call sites to IO instruction.

To support port I/O in decompression code, TDX must be detected before
the decompression code might do port I/O. Detect whether the kernel runs
in a TDX guest.

Add an early_is_tdx_guest() interface to query the cached TDX guest
status in the decompression code.

TDX is detected with CPUID. Make cpuid_count() accessible outside
boot/cpuflags.c.

TDX detection in the main kernel is very similar. Move common bits
into <asm/shared/tdx.h>.

The actual port I/O paravirtualization will come later in the series.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lkml.kernel.org/r/20220405232939.73860-13-kirill.shutemov@linux.intel.com
2022-04-07 08:27:51 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BOOT_CPUFLAGS_H
#define BOOT_CPUFLAGS_H
#include <asm/cpufeatures.h>
#include <asm/processor-flags.h>
struct cpu_features {
int level; /* Family, or 64 for x86-64 */
int family; /* Family, always */
int model;
u32 flags[NCAPINTS];
};
extern struct cpu_features cpu;
extern u32 cpu_vendor[3];
int has_eflag(unsigned long mask);
void get_cpuflags(void);
void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d);
#endif