Files
system76-edk2/UefiCpuPkg/CpuDxe/CpuGdt.h
Tom Lendacky 0d7601e546 UefiCpuPkg: Add a 16-bit protected mode code segment descriptor
BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198

A hypervisor is not allowed to update an SEV-ES guests register state,
so when booting an SEV-ES guest AP, the hypervisor is not allowed to
set the RIP to the guest requested value. Instead, an SEV-ES AP must be
transition from 64-bit long mode to 16-bit real mode in response to an
INIT-SIPI-SIPI sequence. This requires a 16-bit code segment descriptor.
For PEI, create this descriptor in the reset vector GDT table. For DXE,
create this descriptor from the newly reserved entry at location 0x28.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Regression-tested-by: Laszlo Ersek <lersek@redhat.com>
2020-08-17 02:46:39 +00:00

69 lines
1.7 KiB
C

/** @file
C based implementation of IA32 interrupt handling only
requiring a minimal assembly interrupt entry point.
Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#ifndef _CPU_GDT_H_
#define _CPU_GDT_H_
//
// Local structure definitions
//
#pragma pack (1)
//
// Global Descriptor Entry structures
//
typedef struct _GDT_ENTRY {
UINT16 Limit15_0;
UINT16 Base15_0;
UINT8 Base23_16;
UINT8 Type;
UINT8 Limit19_16_and_flags;
UINT8 Base31_24;
} GDT_ENTRY;
typedef
struct _GDT_ENTRIES {
GDT_ENTRY Null;
GDT_ENTRY Linear;
GDT_ENTRY LinearCode;
GDT_ENTRY SysData;
GDT_ENTRY SysCode;
GDT_ENTRY SysCode16;
GDT_ENTRY LinearData64;
GDT_ENTRY LinearCode64;
GDT_ENTRY Spare5;
} GDT_ENTRIES;
#pragma pack ()
#define NULL_SEL OFFSET_OF (GDT_ENTRIES, Null)
#define LINEAR_SEL OFFSET_OF (GDT_ENTRIES, Linear)
#define LINEAR_CODE_SEL OFFSET_OF (GDT_ENTRIES, LinearCode)
#define SYS_DATA_SEL OFFSET_OF (GDT_ENTRIES, SysData)
#define SYS_CODE_SEL OFFSET_OF (GDT_ENTRIES, SysCode)
#define SYS_CODE16_SEL OFFSET_OF (GDT_ENTRIES, SysCode16)
#define LINEAR_DATA64_SEL OFFSET_OF (GDT_ENTRIES, LinearData64)
#define LINEAR_CODE64_SEL OFFSET_OF (GDT_ENTRIES, LinearCode64)
#define SPARE5_SEL OFFSET_OF (GDT_ENTRIES, Spare5)
#if defined (MDE_CPU_IA32)
#define CPU_CODE_SEL LINEAR_CODE_SEL
#define CPU_DATA_SEL LINEAR_SEL
#elif defined (MDE_CPU_X64)
#define CPU_CODE_SEL LINEAR_CODE64_SEL
#define CPU_DATA_SEL LINEAR_DATA64_SEL
#else
#error CPU type not supported for CPU GDT initialization!
#endif
#endif // _CPU_GDT_H_