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

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: Unbreak unnecessarily broken lines. ]

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/20220307213356.2797205-28-brijesh.singh@amd.com

1 files changed, 23 insertions, 45 deletions

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 9a824af69961..b0c1dffc5510 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -20,48 +20,31 @@
  */
 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)
 {
-	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;
-		}
+	unsigned long rsdp_addr;
+	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.
+	 */
+	rsdp_addr = efi_find_vendor_table(boot_params, cfg_tbl_pa, cfg_tbl_len,
+					  ACPI_20_TABLE_GUID);
+	if (rsdp_addr)
+		return (acpi_physical_address)rsdp_addr;
+
+	/* No ACPI_20_TABLE_GUID found, fallback to ACPI_TABLE_GUID. */
+	rsdp_addr = efi_find_vendor_table(boot_params, cfg_tbl_pa, cfg_tbl_len,
+					  ACPI_TABLE_GUID);
+	if (rsdp_addr)
+		return (acpi_physical_address)rsdp_addr;
+
+	debug_putstr("Error getting RSDP address.\n");
 #endif
-	return rsdp_addr;
+	return 0;
 }
 
 /* EFI/kexec support is 64-bit only. */
@@ -109,7 +92,7 @@ static acpi_physical_address kexec_get_rsdp_addr(void)
 	if (!systab)
 		error("EFI system table not found in kexec boot_params.");
 
-	return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables, true);
+	return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables);
 }
 #else
 static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
@@ -123,15 +106,10 @@ static acpi_physical_address efi_get_rsdp_addr(void)
 	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)
-		efi_64 = true;
-	else if (et == EFI_TYPE_32)
-		efi_64 = false;
-	else
+	if (et == EFI_TYPE_NONE)
 		return 0;
 
 	systab_pa = efi_get_system_table(boot_params);
@@ -142,7 +120,7 @@ static acpi_physical_address efi_get_rsdp_addr(void)
 	if (ret || !cfg_tbl_pa)
 		error("EFI config table not found.");
 
-	return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len, efi_64);
+	return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len);
 #else
 	return 0;
 #endif