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x86/compressed/acpi: Move EFI config table lookup to helper

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Future patches for SEV-SNP-validated CPUID will also require early
parsing of the EFI configuration. Incrementally move the related code
into a set of helpers that can be re-used for that purpose.

  [ bp: Remove superfluous zeroing of a stack variable. ]

Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-27-brijesh.singh@amd.com
This commit is contained in:
Michael Roth 2022-02-24 10:56:06 -06:00 committed by Borislav Petkov
parent 58f3e6b71f
commit 61c14ceda8
3 changed files with 60 additions and 17 deletions
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25
arch/x86/boot/compressed/acpi.c
View File

@ -118,10 +118,13 @@ static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
static acpi_physical_address efi_get_rsdp_addr(void)
{
#ifdef CONFIG_EFI
unsigned long systab_pa, config_tables;
unsigned long cfg_tbl_pa = 0;
unsigned int cfg_tbl_len;
unsigned long systab_pa;
unsigned int nr_tables;
enum efi_type et;
bool efi_64;
int ret;
et = efi_get_type(boot_params);
if (et == EFI_TYPE_64)
@ -135,23 +138,11 @@ static acpi_physical_address efi_get_rsdp_addr(void)
if (!systab_pa)
error("EFI support advertised, but unable to locate system table.");
/* Handle EFI bitness properly */
if (efi_64) {
efi_system_table_64_t *stbl = (efi_system_table_64_t *)systab_pa;
ret = efi_get_conf_table(boot_params, &cfg_tbl_pa, &cfg_tbl_len);
if (ret || !cfg_tbl_pa)
error("EFI config table not found.");
config_tables = stbl->tables;
nr_tables = stbl->nr_tables;
} else {
efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab_pa;
config_tables = stbl->tables;
nr_tables = stbl->nr_tables;
}
if (!config_tables)
error("EFI config tables not found.");
return __efi_get_rsdp_addr(config_tables, nr_tables, efi_64);
return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len, efi_64);
#else
return 0;
#endif

43
arch/x86/boot/compressed/efi.c
View File

@ -77,3 +77,46 @@ unsigned long efi_get_system_table(struct boot_params *bp)
return sys_tbl_pa;
}
/**
* efi_get_conf_table - Given a pointer to boot_params, locate and return the physical
* address of EFI configuration table.
*
* @bp: pointer to boot_params
* @cfg_tbl_pa: location to store physical address of config table
* @cfg_tbl_len: location to store number of config table entries
*
* Return: 0 on success. On error, return params are left unchanged.
*/
int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
unsigned int *cfg_tbl_len)
{
unsigned long sys_tbl_pa;
enum efi_type et;
int ret;
if (!cfg_tbl_pa || !cfg_tbl_len)
return -EINVAL;
sys_tbl_pa = efi_get_system_table(bp);
if (!sys_tbl_pa)
return -EINVAL;
/* Handle EFI bitness properly */
et = efi_get_type(bp);
if (et == EFI_TYPE_64) {
efi_system_table_64_t *stbl = (efi_system_table_64_t *)sys_tbl_pa;
*cfg_tbl_pa = stbl->tables;
*cfg_tbl_len = stbl->nr_tables;
} else if (et == EFI_TYPE_32) {
efi_system_table_32_t *stbl = (efi_system_table_32_t *)sys_tbl_pa;
*cfg_tbl_pa = stbl->tables;
*cfg_tbl_len = stbl->nr_tables;
} else {
return -EINVAL;
}
return 0;
}

9
arch/x86/boot/compressed/misc.h
View File

@ -186,6 +186,8 @@ enum efi_type {
/* 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);
#else
static inline enum efi_type efi_get_type(struct boot_params *bp)
{
@ -196,6 +198,13 @@ 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;
}
#endif /* CONFIG_EFI */
#endif /* BOOT_COMPRESSED_MISC_H */