Messages in this thread Patch in this message | | | From | "Kirill A. Shutemov" <> | Subject | [PATCH 09/26] x86/tdx: Detect TDX at early kernel decompression time | Date | Tue, 14 Dec 2021 18:02:47 +0300 |
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From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
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 size is small enough and hence patching it will not bloat the image size a lot.
To support port I/O in decompression code, TDX must be detected before the decompression code might do port I/O. Add support to detect for TDX guest support before console_init() in the extract_kernel(). Detecting it above the console_init() is early enough for patching port I/O.
Add an early_is_tdx_guest() interface to get the cached TDX guest status in the decompression code.
The actual port I/O paravirtualization will come later in the series.
Reviewed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- arch/x86/boot/compressed/Makefile | 1 + arch/x86/boot/compressed/misc.c | 8 ++++++++ arch/x86/boot/compressed/misc.h | 2 ++ arch/x86/boot/compressed/tdx.c | 33 +++++++++++++++++++++++++++++++ arch/x86/boot/compressed/tdx.h | 16 +++++++++++++++ arch/x86/boot/cpuflags.c | 13 ++++++++++-- arch/x86/boot/cpuflags.h | 2 ++ 7 files changed, 73 insertions(+), 2 deletions(-) create mode 100644 arch/x86/boot/compressed/tdx.c create mode 100644 arch/x86/boot/compressed/tdx.h
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/misc.c b/arch/x86/boot/compressed/misc.c index a4339cb2d247..1b07755a5efd 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -370,6 +370,14 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, lines = boot_params->screen_info.orig_video_lines; cols = boot_params->screen_info.orig_video_cols; + /* + * Detect if we are running in TDX guest environment. + * + * It has to be done before console_init() to use paravirtualized + * port I/O oprations if needed. + */ + early_tdx_detect(); + console_init(); /* diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index 16ed360b6692..0d8e275a9d96 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -28,6 +28,8 @@ #include <asm/bootparam.h> #include <asm/desc_defs.h> +#include "tdx.h" + #define BOOT_CTYPE_H #include <linux/acpi.h> diff --git a/arch/x86/boot/compressed/tdx.c b/arch/x86/boot/compressed/tdx.c new file mode 100644 index 000000000000..2ee7d0bdf907 --- /dev/null +++ b/arch/x86/boot/compressed/tdx.c @@ -0,0 +1,33 @@ +// 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 +#define TDX_IDENT "IntelTDX " + +static bool tdx_guest_detected; + +void early_tdx_detect(void) +{ + u32 eax, sig[3]; + + if (cpuid_max_leaf() < TDX_CPUID_LEAF_ID) + return; + + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]); + + if (memcmp(TDX_IDENT, sig, 12)) + return; + + /* Cache TDX guest feature status */ + tdx_guest_detected = true; +} + +bool early_is_tdx_guest(void) +{ + return tdx_guest_detected; +} diff --git a/arch/x86/boot/compressed/tdx.h b/arch/x86/boot/compressed/tdx.h new file mode 100644 index 000000000000..18970c09512e --- /dev/null +++ b/arch/x86/boot/compressed/tdx.h @@ -0,0 +1,16 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2021 Intel Corporation */ +#ifndef BOOT_COMPRESSED_TDX_H +#define BOOT_COMPRESSED_TDX_H + +#include <linux/types.h> + +#ifdef CONFIG_INTEL_TDX_GUEST +void early_tdx_detect(void); +bool early_is_tdx_guest(void); +#else +static inline void early_tdx_detect(void) { }; +static inline bool early_is_tdx_guest(void) { return false; } +#endif + +#endif diff --git a/arch/x86/boot/cpuflags.c b/arch/x86/boot/cpuflags.c index a0b75f73dc63..7f97bf88c540 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 +81,16 @@ static inline void cpuid_count(u32 id, u32 count, ); } +/* Get maximum leaf value using CPUID(0) */ +u32 cpuid_max_leaf(void) +{ + u32 eax, ebx, ecx, edx; + + cpuid_count(0, 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..dea67090a22f 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_max_leaf(void); #endif -- 2.32.0
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