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linux/arch/x86/boot/compressed/misc.h
Nikunj A Dadhania 8c29f01654 x86/sev: Add SEV-SNP guest feature negotiation support 
The hypervisor can enable various new features (SEV_FEATURES[1:63]) and start a
SNP guest. Some of these features need guest side implementation. If any of
these features are enabled without it, the behavior of the SNP guest will be
undefined.  It may fail booting in a non-obvious way making it difficult to
debug.

Instead of allowing the guest to continue and have it fail randomly later,
detect this early and fail gracefully.

The SEV_STATUS MSR indicates features which the hypervisor has enabled.  While
booting, SNP guests should ascertain that all the enabled features have guest
side implementation. In case a feature is not implemented in the guest, the
guest terminates booting with GHCB protocol Non-Automatic Exit(NAE) termination
request event, see "SEV-ES Guest-Hypervisor Communication Block Standardization"
document (currently at https://developer.amd.com/wp-content/resources/56421.pdf),
section "Termination Request".

Populate SW_EXITINFO2 with mask of unsupported features that the hypervisor can
easily report to the user.

More details in the AMD64 APM Vol 2, Section "SEV_STATUS MSR".

  [ bp:
    - Massage.
    - Move snp_check_features() call to C code.
    Note: the CC:stable@ aspect here is to be able to protect older, stable
    kernels when running on newer hypervisors. Or not "running" but fail
    reliably and in a well-defined manner instead of randomly. ]

Fixes: cbd3d4f7c4 ("x86/sev: Check SEV-SNP features support")
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230118061943.534309-1-nikunj@amd.com
2023-01-19 17:29:58 +01:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BOOT_COMPRESSED_MISC_H
#define BOOT_COMPRESSED_MISC_H
/*
* Special hack: we have to be careful, because no indirections are allowed here,
* and paravirt_ops is a kind of one. As it will only run in baremetal anyway,
* we just keep it from happening. (This list needs to be extended when new
* paravirt and debugging variants are added.)
*/
#undef CONFIG_PARAVIRT
#undef CONFIG_PARAVIRT_XXL
#undef CONFIG_PARAVIRT_SPINLOCKS
#undef CONFIG_KASAN
#undef CONFIG_KASAN_GENERIC
#define __NO_FORTIFY
/* cpu_feature_enabled() cannot be used this early */
#define USE_EARLY_PGTABLE_L5
#include <linux/linkage.h>
#include <linux/screen_info.h>
#include <linux/elf.h>
#include <asm/page.h>
#include <asm/boot.h>
#include <asm/bootparam.h>
#include <asm/desc_defs.h>
#include "tdx.h"
#define BOOT_CTYPE_H
#include <linux/acpi.h>
#define BOOT_BOOT_H
#include "../ctype.h"
#include "../io.h"
#include "efi.h"
#ifdef CONFIG_X86_64
#define memptr long
#else
#define memptr unsigned
#endif
/* boot/compressed/vmlinux start and end markers */
extern char _head[], _end[];
/* misc.c */
extern memptr free_mem_ptr;
extern memptr free_mem_end_ptr;
void *malloc(int size);
void free(void *where);
extern struct boot_params *boot_params;
void __putstr(const char *s);
void __puthex(unsigned long value);
#define error_putstr(__x) __putstr(__x)
#define error_puthex(__x) __puthex(__x)
#ifdef CONFIG_X86_VERBOSE_BOOTUP
#define debug_putstr(__x) __putstr(__x)
#define debug_puthex(__x) __puthex(__x)
#define debug_putaddr(__x) { \
debug_putstr(#__x ": 0x"); \
debug_puthex((unsigned long)(__x)); \
debug_putstr("\n"); \
}
#else
static inline void debug_putstr(const char *s)
{ }
static inline void debug_puthex(unsigned long value)
{ }
#define debug_putaddr(x) /* */
#endif
/* cmdline.c */
int cmdline_find_option(const char *option, char *buffer, int bufsize);
int cmdline_find_option_bool(const char *option);
struct mem_vector {
u64 start;
u64 size;
};
#ifdef CONFIG_RANDOMIZE_BASE
/* kaslr.c */
void choose_random_location(unsigned long input,
unsigned long input_size,
unsigned long *output,
unsigned long output_size,
unsigned long *virt_addr);
#else
static inline void choose_random_location(unsigned long input,
unsigned long input_size,
unsigned long *output,
unsigned long output_size,
unsigned long *virt_addr)
{
}
#endif
/* cpuflags.c */
bool has_cpuflag(int flag);
#ifdef CONFIG_X86_64
extern int set_page_decrypted(unsigned long address);
extern int set_page_encrypted(unsigned long address);
extern int set_page_non_present(unsigned long address);
extern unsigned char _pgtable[];
#endif
#ifdef CONFIG_EARLY_PRINTK
/* early_serial_console.c */
extern int early_serial_base;
void console_init(void);
#else
static const int early_serial_base;
static inline void console_init(void)
{ }
#endif
#ifdef CONFIG_AMD_MEM_ENCRYPT
void sev_enable(struct boot_params *bp);
void snp_check_features(void);
void sev_es_shutdown_ghcb(void);
extern bool sev_es_check_ghcb_fault(unsigned long address);
void snp_set_page_private(unsigned long paddr);
void snp_set_page_shared(unsigned long paddr);
void sev_prep_identity_maps(unsigned long top_level_pgt);
#else
static inline void sev_enable(struct boot_params *bp)
{
/*
* bp->cc_blob_address should only be set by boot/compressed kernel.
* Initialize it to 0 unconditionally (thus here in this stub too) to
* ensure that uninitialized values from buggy bootloaders aren't
* propagated.
*/
if (bp)
bp->cc_blob_address = 0;
}
static inline void snp_check_features(void) { }
static inline void sev_es_shutdown_ghcb(void) { }
static inline bool sev_es_check_ghcb_fault(unsigned long address)
{
return false;
}
static inline void snp_set_page_private(unsigned long paddr) { }
static inline void snp_set_page_shared(unsigned long paddr) { }
static inline void sev_prep_identity_maps(unsigned long top_level_pgt) { }
#endif
/* acpi.c */
#ifdef CONFIG_ACPI
acpi_physical_address get_rsdp_addr(void);
#else
static inline acpi_physical_address get_rsdp_addr(void) { return 0; }
#endif
#if defined(CONFIG_RANDOMIZE_BASE) && defined(CONFIG_MEMORY_HOTREMOVE) && defined(CONFIG_ACPI)
extern struct mem_vector immovable_mem[MAX_NUMNODES*2];
int count_immovable_mem_regions(void);
#else
static inline int count_immovable_mem_regions(void) { return 0; }
#endif
/* ident_map_64.c */
#ifdef CONFIG_X86_5LEVEL
extern unsigned int __pgtable_l5_enabled, pgdir_shift, ptrs_per_p4d;
#endif
extern void kernel_add_identity_map(unsigned long start, unsigned long end);
/* Used by PAGE_KERN* macros: */
extern pteval_t __default_kernel_pte_mask;
/* idt_64.c */
extern gate_desc boot_idt[BOOT_IDT_ENTRIES];
extern struct desc_ptr boot_idt_desc;
#ifdef CONFIG_X86_64
void cleanup_exception_handling(void);
#else
static inline void cleanup_exception_handling(void) { }
#endif
/* IDT Entry Points */
void boot_page_fault(void);
void boot_stage1_vc(void);
void boot_stage2_vc(void);
unsigned long sev_verify_cbit(unsigned long cr3);
enum efi_type {
EFI_TYPE_64,
EFI_TYPE_32,
EFI_TYPE_NONE,
};
#ifdef CONFIG_EFI
/* helpers for early EFI config table access */
enum efi_type efi_get_type(struct boot_params *bp);
unsigned long efi_get_system_table(struct boot_params *bp);
int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
unsigned int *cfg_tbl_len);
unsigned long efi_find_vendor_table(struct boot_params *bp,
unsigned long cfg_tbl_pa,
unsigned int cfg_tbl_len,
efi_guid_t guid);
#else
static inline enum efi_type efi_get_type(struct boot_params *bp)
{
return EFI_TYPE_NONE;
}
static inline unsigned long efi_get_system_table(struct boot_params *bp)
{
return 0;
}
static inline int efi_get_conf_table(struct boot_params *bp,
unsigned long *cfg_tbl_pa,
unsigned int *cfg_tbl_len)
{
return -ENOENT;
}
static inline unsigned long efi_find_vendor_table(struct boot_params *bp,
unsigned long cfg_tbl_pa,
unsigned int cfg_tbl_len,
efi_guid_t guid)
{
return 0;
}
#endif /* CONFIG_EFI */
#endif /* BOOT_COMPRESSED_MISC_H */
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