From 4b05f81504bfcaab51083d3a271fada75e6b8904 Mon Sep 17 00:00:00 2001 From: Kuppuswamy Sathyanarayanan Date: Wed, 6 Apr 2022 02:29:21 +0300 Subject: 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 . The actual port I/O paravirtualization will come later in the series. Signed-off-by: Kuppuswamy Sathyanarayanan Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Tony Luck Reviewed-by: Dave Hansen Link: https://lkml.kernel.org/r/20220405232939.73860-13-kirill.shutemov@linux.intel.com --- arch/x86/boot/compressed/tdx.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 arch/x86/boot/compressed/tdx.c (limited to 'arch/x86/boot/compressed/tdx.c') diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c new file mode 100644 index 000000000000..5f6d01a2f1f4 --- /dev/null +++ b/arch/x86/boot/compressed/tdx.c @@ -0,0 +1,16 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "../cpuflags.h" +#include "../string.h" + +#include + +void early_tdx_detect(void) +{ + u32 eax, sig[3]; + + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]); + + if (memcmp(TDX_IDENT, sig, sizeof(sig))) + return; +} -- cgit