[PATCH v9 27/43] x86/compressed/acpi: Move EFI vendor table lookup to helper

Brijesh Singh
2022-01-28T17:20:42Z

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 | 67 +++++++++++-------------------
arch/x86/boot/compressed/efi.c | 72 +++++++++++++++++++++++++++++++++
arch/x86/boot/compressed/misc.h | 13 ++++++
3 files changed, 108 insertions(+), 44 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 9a824af69961..d505335bcc25 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; }
@@ -127,11 +110,7 @@ static acpi_physical_address efi_get_rsdp_addr(void)
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 +121,7 @@ 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
diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
index feb00c6b4919..6413a808b2e7 100644
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -122,3 +122,75 @@ 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,
+ enum efi_type et)
+{
+ if (et == EFI_TYPE_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 if (et == EFI_TYPE_32) {
+ 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;
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * efi_find_vendor_table - Given EFI config table, search it for the physical
+ * address of the vendor table associated with GUID.
+ *
+ * @boot_params: pointer to boot_params
+ * @cfg_tbl_pa: pointer to EFI configuration table
+ * @cfg_tbl_len: number of entries in EFI configuration table
+ * @guid: GUID of vendor table
+ *
+ * Return: vendor table address on success. On error, return 0.
+ */
+unsigned long efi_find_vendor_table(struct boot_params *boot_params,
+ unsigned long cfg_tbl_pa,
+ unsigned int cfg_tbl_len,
+ efi_guid_t guid)
+{
+ enum efi_type et;
+ unsigned int i;
+
+ et = efi_get_type(boot_params);
+ if (et == EFI_TYPE_NONE)
+ return 0;
+
+ for (i = 0; i < cfg_tbl_len; i++) {
+ unsigned long vendor_tbl_pa;
+ efi_guid_t vendor_tbl_guid;
+ int ret;
+
+ ret = get_vendor_table((void *)cfg_tbl_pa, i,
+ &vendor_tbl_pa,
+ &vendor_tbl_guid, et);
+ if (ret)
+ return 0;
+
+ if (!efi_guidcmp(guid, vendor_tbl_guid))
+ return vendor_tbl_pa;
+ }
+
+ return 0;
+}
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index 162dbd7443eb..991b46170914 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -23,6 +23,7 @@
#include <linux/screen_info.h>
#include <linux/elf.h>
#include <linux/io.h>
+#include <linux/efi.h>
#include <asm/page.h>
#include <asm/boot.h>
#include <asm/bootparam.h>
@@ -188,6 +189,10 @@ enum efi_type efi_get_type(struct boot_params *boot_params);
unsigned long efi_get_system_table(struct boot_params *boot_params);
int efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
unsigned int *cfg_tbl_len);
+unsigned long efi_find_vendor_table(struct boot_params *boot_params,
+ 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 *boot_params)
{
@@ -205,6 +210,14 @@ static inline int efi_get_conf_table(struct boot_params *boot_params,
{
return -ENOENT;
}
+
+static inline unsigned long efi_find_vendor_table(struct boot_params *boot_params,
+ unsigned long cfg_tbl_pa,
+ unsigned int cfg_tbl_len,
+ efi_guid_t guid)
+{
+ return 0;
+}
#endif /* CONFIG_EFI */

#endif /* BOOT_COMPRESSED_MISC_H */
--
2.25.1