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| author | Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> | 2022-04-06 02:29:21 +0300 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2022-04-07 18:27:51 +0300 |
| commit | 4b05f81504bfcaab51083d3a271fada75e6b8904 (patch) | |
| tree | fcb76e069a285a4bf3c11b78560754cd46aa931a /arch/x86/boot/cpuflags.c | |
| parent | 31d58c4e557d46fa7f8557714250fb6f89c941ae (diff) | |
| download | linux-4b05f81504bfcaab51083d3a271fada75e6b8904.tar.xz | |
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
Diffstat (limited to 'arch/x86/boot/cpuflags.c')
| -rw-r--r-- | arch/x86/boot/cpuflags.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c index a0b75f73dc63..a83d67ec627d 100644 --- a/arch/x86/boot/cpuflags.c +++ b/arch/x86/boot/cpuflags.c @@ -71,8 +71,7 @@ int has_eflag(unsigned long mask) # define EBX_REG "=b" #endif -static inline void cpuid_count(u32 id, u32 count, - u32 *a, u32 *b, u32 *c, u32 *d) +void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d) { asm volatile(".ifnc %%ebx,%3 ; movl %%ebx,%3 ; .endif \n\t" "cpuid \n\t" |