[PATCH v12 26/46] x86/compressed/acpi: Move EFI config table lookup to helper

Brijesh Singh
2022-03-07T21:36:16Z

From: Michael Roth <michael.roth@amd.com>

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.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
arch/x86/boot/compressed/acpi.c | 25 ++++++-------------
arch/x86/boot/compressed/efi.c | 43 +++++++++++++++++++++++++++++++++
arch/x86/boot/compressed/misc.h | 9 +++++++
3 files changed, 60 insertions(+), 17 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 58a3d3f3e305..9a824af69961 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -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;
-
- 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.");
+ ret = efi_get_conf_table(boot_params, &cfg_tbl_pa, &cfg_tbl_len);
+ if (ret || !cfg_tbl_pa)
+ error("EFI config table 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
diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
index 72a81ba1f87b..70acddbbe7af 100644
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -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 = 0;
+ 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;
+}
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index b2acd3ac6525..8815af092a10 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -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 */
--
2.25.1