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