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authorKuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>2022-04-06 02:29:21 +0300
committerDave Hansen <dave.hansen@linux.intel.com>2022-04-07 18:27:51 +0300
commit4b05f81504bfcaab51083d3a271fada75e6b8904 (patch)
treefcb76e069a285a4bf3c11b78560754cd46aa931a /arch/x86/boot/cpuflags.c
parent31d58c4e557d46fa7f8557714250fb6f89c941ae (diff)
downloadlinux-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.c3
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"