[PATCH v8 26/40] x86/compressed/acpi: move EFI vendor table lookup to helper

Brijesh Singh
2021-12-10T15:44:44Z

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 | 50 ++++++++-----------------
arch/x86/boot/compressed/efi.c | 65 +++++++++++++++++++++++++++++++++
arch/x86/boot/compressed/misc.h | 9 +++++
3 files changed, 90 insertions(+), 34 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index fea72a1504ff..0670c8f8888a 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -20,46 +20,28 @@
*/
struct mem_vector immovable_mem[MAX_NUMNODES*2];

-/*
- * Search EFI system tables for RSDP. If both ACPI_20_TABLE_GUID and
- * ACPI_TABLE_GUID are found, take the former, which has more features.
- */
static acpi_physical_address
-__efi_get_rsdp_addr(unsigned long config_tables, unsigned int nr_tables,
- bool efi_64)
+__efi_get_rsdp_addr(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len, bool efi_64)
{
acpi_physical_address rsdp_addr = 0;

#ifdef CONFIG_EFI
- int i;
-
- /* Get EFI tables from systab. */
- for (i = 0; i < nr_tables; i++) {
- acpi_physical_address table;
- efi_guid_t guid;
-
- if (efi_64) {
- efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables + i;
-
- guid = tbl->guid;
- table = tbl->table;
-
- if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) {
- debug_putstr("Error getting RSDP address: EFI config table located above 4GB.\n");
- return 0;
- }
- } else {
- efi_config_table_32_t *tbl = (efi_config_table_32_t *)config_tables + i;
-
- guid = tbl->guid;
- table = tbl->table;
- }
+ int ret;

- if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
- rsdp_addr = table;
- else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
- return table;
- }
+ /*
+ * Search EFI system tables for RSDP. Preferred is ACPI_20_TABLE_GUID to
+ * ACPI_TABLE_GUID because it has more features.
+ */
+ ret = efi_find_vendor_table(cfg_tbl_pa, cfg_tbl_len, ACPI_20_TABLE_GUID,
+ efi_64, (unsigned long *)&rsdp_addr);
+ if (!ret)
+ return rsdp_addr;
+
+ /* No ACPI_20_TABLE_GUID found, fallback to ACPI_TABLE_GUID. */
+ ret = efi_find_vendor_table(cfg_tbl_pa, cfg_tbl_len, ACPI_TABLE_GUID,
+ efi_64, (unsigned long *)&rsdp_addr);
+ if (ret)
+ debug_putstr("Error getting RSDP address.\n");
#endif
return rsdp_addr;
}
diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
index 08ad517b0731..c1ddc72ef4d9 100644
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -112,3 +112,68 @@ int efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_p

return 0;
}
+
+/* Get vendor table address/guid from EFI config table at the given index */
+static int get_vendor_table(void *cfg_tbl, unsigned int idx,
+ unsigned long *vendor_tbl_pa,
+ efi_guid_t *vendor_tbl_guid,
+ bool efi_64)
+{
+ if (efi_64) {
+ efi_config_table_64_t *tbl_entry =
+ (efi_config_table_64_t *)cfg_tbl + idx;
+
+ if (!IS_ENABLED(CONFIG_X86_64) && tbl_entry->table >> 32) {
+ debug_putstr("Error: EFI config table entry located above 4GB.\n");
+ return -EINVAL;
+ }
+
+ *vendor_tbl_pa = tbl_entry->table;
+ *vendor_tbl_guid = tbl_entry->guid;
+
+ } else {
+ efi_config_table_32_t *tbl_entry =
+ (efi_config_table_32_t *)cfg_tbl + idx;
+
+ *vendor_tbl_pa = tbl_entry->table;
+ *vendor_tbl_guid = tbl_entry->guid;
+ }
+
+ return 0;
+}
+
+/**
+ * efi_find_vendor_table - Given EFI config table, search it for the physical
+ * address of the vendor table associated with GUID.
+ *
+ * @cfg_tbl_pa: pointer to EFI configuration table
+ * @cfg_tbl_len: number of entries in EFI configuration table
+ * @guid: GUID of vendor table
+ * @efi_64: true if using 64-bit EFI
+ * @vendor_tbl_pa: location to store physical address of vendor table
+ *
+ * Return: 0 on success. On error, return params are left unchanged.
+ */
+int efi_find_vendor_table(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len,
+ efi_guid_t guid, bool efi_64, unsigned long *vendor_tbl_pa)
+{
+ unsigned int i;
+
+ for (i = 0; i < cfg_tbl_len; i++) {
+ unsigned long vendor_tbl_pa_tmp;
+ efi_guid_t vendor_tbl_guid;
+ int ret;
+
+ if (get_vendor_table((void *)cfg_tbl_pa, i,
+ &vendor_tbl_pa_tmp,
+ &vendor_tbl_guid, efi_64))
+ return -EINVAL;
+
+ if (!efi_guidcmp(guid, vendor_tbl_guid)) {
+ *vendor_tbl_pa = vendor_tbl_pa_tmp;
+ return 0;
+ }
+ }
+
+ return -ENOENT;
+}
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 1c69592e83da..e9fde1482fbe 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -183,6 +183,8 @@ int efi_get_system_table(struct boot_params *boot_params,
unsigned long *sys_tbl_pa, bool *is_efi_64);
int efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
unsigned int *cfg_tbl_len, bool *is_efi_64);
+int efi_find_vendor_table(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len,
+ efi_guid_t guid, bool efi_64, unsigned long *vendor_tbl_pa);
#else
static inline int
efi_get_system_table(struct boot_params *boot_params,
@@ -197,6 +199,13 @@ efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
{
return -ENOENT;
}
+
+static inline int
+efi_find_vendor_table(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len,
+ efi_guid_t guid, bool efi_64, unsigned long *vendor_tbl_pa)
+{
+ return -ENOENT;
+}
#endif /* CONFIG_EFI */

#endif /* BOOT_COMPRESSED_MISC_H */
--
2.25.1