[PATCH v6 29/42] x86/compressed/acpi: move EFI config table lookup to helper

Brijesh Singh
2021-10-08T18:06:13Z

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 | 52 +++++----------------------------
arch/x86/boot/compressed/efi.c | 42 ++++++++++++++++++++++++++
arch/x86/boot/compressed/misc.h | 9 ++++++
3 files changed, 58 insertions(+), 45 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 255f6959c090..d43ff3ff573b 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -117,54 +117,16 @@ 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, config_tables;
- unsigned int nr_tables;
- struct efi_info *ei;
+ unsigned long cfg_tbl_pa = 0;
+ unsigned int cfg_tbl_len;
bool efi_64;
- char *sig;
-
- ei = &boot_params->efi_info;
- sig = (char *)&ei->efi_loader_signature;
-
- if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
- efi_64 = true;
- } else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {
- efi_64 = false;
- } else {
- debug_putstr("Wrong EFI loader signature.\n");
- return 0;
- }
-
- /* Get systab from boot params. */
-#ifdef CONFIG_X86_64
- systab = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
-#else
- if (ei->efi_systab_hi || ei->efi_memmap_hi) {
- debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n");
- return 0;
- }
- systab = ei->efi_systab;
-#endif
- if (!systab)
- error("EFI system table not found.");
-
- /* Handle EFI bitness properly */
- if (efi_64) {
- efi_system_table_64_t *stbl = (efi_system_table_64_t *)systab;
-
- config_tables = stbl->tables;
- nr_tables = stbl->nr_tables;
- } else {
- efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab;
-
- config_tables = stbl->tables;
- nr_tables = stbl->nr_tables;
- }
+ int ret;

- if (!config_tables)
- error("EFI config tables not found.");
+ ret = efi_get_conf_table(boot_params, &cfg_tbl_pa, &cfg_tbl_len, &efi_64);
+ 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 306b287b7368..e5f39b3f5665 100644
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -62,3 +62,45 @@ int efi_get_system_table(struct boot_params *boot_params, unsigned long *sys_tbl
*is_efi_64 = efi_64;
return 0;
}
+
+/**
+ * Given boot_params, locate EFI system table from it and return the physical
+ * address EFI configuration table.
+ *
+ * @boot_params: 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
+ * @is_efi_64: location to store whether using 64-bit EFI or not
+ *
+ * Returns 0 on success. On error, return params are left unchanged.
+ */
+int efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
+ unsigned int *cfg_tbl_len, bool *is_efi_64)
+{
+ unsigned long sys_tbl_pa = 0;
+ int ret;
+
+ if (!cfg_tbl_pa || !cfg_tbl_len || !is_efi_64)
+ return -EINVAL;
+
+ ret = efi_get_system_table(boot_params, &sys_tbl_pa, is_efi_64);
+ if (ret)
+ return ret;
+
+ /* Handle EFI bitness properly */
+ if (*is_efi_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 {
+ 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;
+ }
+
+ return 0;
+}
diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
index f86ff866fd7a..b72fd860362a 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -179,6 +179,8 @@ unsigned long sev_verify_cbit(unsigned long cr3);
/* helpers for early EFI config table access */
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);
#else
static inline int
efi_get_system_table(struct boot_params *boot_params,
@@ -186,6 +188,13 @@ efi_get_system_table(struct boot_params *boot_params,
{
return -ENOENT;
}
+
+static inline int
+efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
+ unsigned int *cfg_tbl_len, bool *is_efi_64)
+{
+ return -ENOENT;
+}
#endif /* CONFIG_EFI */

#endif /* BOOT_COMPRESSED_MISC_H */
--
2.25.1