Messages in this thread Patch in this message | | | From | Kuppuswamy Sathyanarayanan <> | Subject | [PATCH v2 02/10] x86/tdx: Add early_is_tdx_guest() interface | Date | Sat, 26 Jun 2021 07:17:10 -0700 |
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Add helper function to detect TDX feature support. It will be used to protect TDX specific code in decompression code (for example to add TDX specific I/O fixes in decompression code).
Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> ---
Changes since v1: * Modified cpuid_has_tdx_guest() to use cpuid_count() instead of native_cpuid(). * Reused cpuid_count() from cpuflags.c. * Added a new function cpuid_eax(). * Renamed native_cpuid_has_tdx_guest() as early_cpuid_has_tdx_guest().
arch/x86/boot/compressed/Makefile | 1 + arch/x86/boot/compressed/tdx.c | 31 +++++++++++++++++++++++++++++++ arch/x86/boot/cpuflags.c | 12 ++++++++++-- arch/x86/boot/cpuflags.h | 2 ++ 4 files changed, 44 insertions(+), 2 deletions(-) create mode 100644 arch/x86/boot/compressed/tdx.c
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 431bf7f846c3..22a2a6cc2ab4 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -98,6 +98,7 @@ ifdef CONFIG_X86_64 endif vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o +vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o efi-obj-$(CONFIG_EFI_STUB) = $(objtree)/drivers/firmware/efi/libstub/lib.a diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c new file mode 100644 index 000000000000..51cf655d8b60 --- /dev/null +++ b/arch/x86/boot/compressed/tdx.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * tdx.c - Early boot code for TDX + */ + +#include "../cpuflags.h" +#include "../string.h" + +#define TDX_CPUID_LEAF_ID 0x21 + +static int tdx_guest = -1; + +static inline bool early_cpuid_has_tdx_guest(void) +{ + u32 eax = TDX_CPUID_LEAF_ID, sig[3] = {0}; + + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) + return false; + + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[1], &sig[2]); + + return !memcmp("IntelTDX ", sig, 12); +} + +bool early_is_tdx_guest(void) +{ + if (tdx_guest < 0) + tdx_guest = early_cpuid_has_tdx_guest(); + + return !!tdx_guest; +} diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c index a0b75f73dc63..102613a092aa 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" @@ -82,6 +81,15 @@ static inline void cpuid_count(u32 id, u32 count, ); } +u32 cpuid_eax(u32 id) +{ + u32 eax, ebx, ecx, edx; + + cpuid_count(id, 0, &eax, &ebx, &ecx, &edx); + + return eax; +} + #define cpuid(id, a, b, c, d) cpuid_count(id, 0, a, b, c, d) void get_cpuflags(void) diff --git a/arch/x86/boot/cpuflags.h b/arch/x86/boot/cpuflags.h index 2e20814d3ce3..5a72233eb8fd 100644 --- a/arch/x86/boot/cpuflags.h +++ b/arch/x86/boot/cpuflags.h @@ -17,5 +17,7 @@ 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); +u32 cpuid_eax(u32 id); #endif -- 2.25.1
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