[PATCH v8 25/40] x86/compressed/acpi: move EFI config table lookup to helper

Brijesh Singh
2021-12-10T15:45:41Z

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 | 42 +++++++++++++++++++++++++++++++++
arch/x86/boot/compressed/misc.h | 9 +++++++
3 files changed, 58 insertions(+), 18 deletions(-)

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 9e784bd7b2e6..fea72a1504ff 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -117,8 +117,9 @@ 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_tbl_pa, config_tables;
- unsigned int nr_tables;
+ unsigned long cfg_tbl_pa = 0;
+ unsigned long systab_tbl_pa;
+ unsigned int cfg_tbl_len;
bool efi_64;
int ret;

@@ -134,23 +135,11 @@ static acpi_physical_address efi_get_rsdp_addr(void)
if (ret)
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_tbl_pa;
+ 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.");

- config_tables = stbl->tables;
- nr_tables = stbl->nr_tables;
- } else {
- efi_system_table_32_t *stbl = (efi_system_table_32_t *)systab_tbl_pa;
-
- config_tables = stbl->tables;
- nr_tables = stbl->nr_tables;
- }
-
- if (!config_tables)
- error("EFI config tables 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 1c626d28f07e..08ad517b0731 100644
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -70,3 +70,45 @@ int efi_get_system_table(struct boot_params *boot_params, unsigned long *sys_tbl
*is_efi_64 = efi_64;
return 0;
}
+
+/**
+ * efi_get_conf_table - 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
+ *
+ * Return: 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 165640f64b71..1c69592e83da 100644
--- a/arch/x86/boot/compressed/misc.h
+++ b/arch/x86/boot/compressed/misc.h
@@ -181,6 +181,8 @@ 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,
@@ -188,6 +190,13 @@ 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