Re: [PATCH Part1 v5 26/38] x86/compressed/acpi: move EFI config table access to common code

Borislav Petkov
2021-08-25T15:17:51Z

On Fri, Aug 20, 2021 at 10:19:21AM -0500, Brijesh Singh wrote:
> From: Michael Roth <michael.roth@amd.com>
>
> Future patches for SEV-SNP-validated CPUID will also require early
> parsing of the EFI configuration. 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/Makefile | 1 +
> arch/x86/boot/compressed/acpi.c | 113 +++++--------------
> arch/x86/boot/compressed/efi.c | 178 ++++++++++++++++++++++++++++++
> arch/x86/boot/compressed/misc.h | 43 ++++++++
> 4 files changed, 251 insertions(+), 84 deletions(-)
> create mode 100644 arch/x86/boot/compressed/efi.c

Ok, better, but this patch needs splitting. And I have a good idea how:
in at least three patches:

1. Add efi_get_system_table() and use it
2. Add efi_get_conf_table() and use it
3. Add efi_find_vendor_table() and use it

This will facilitate review immensely.

Also, here's a diff ontop of what to do also, style-wise.

- change how you look for the preferred vendor table along with commenting what you do
- shorten variable names so that you don't have so many line breaks.

Thx.

diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
index 3a3f997d7210..c22b21e94a95 100644
--- a/arch/x86/boot/compressed/acpi.c
+++ b/arch/x86/boot/compressed/acpi.c
@@ -20,27 +20,29 @@
*/
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_table_pa,
- unsigned int config_table_len, 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 ret;

- ret = efi_find_vendor_table(config_table_pa, config_table_len,
- ACPI_20_TABLE_GUID, efi_64,
- (unsigned long *)&rsdp_addr);
- if (ret == -ENOENT)
- ret = efi_find_vendor_table(config_table_pa, config_table_len,
- ACPI_TABLE_GUID, efi_64,
- (unsigned long *)&rsdp_addr);
+ /*
+ * 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;
}
@@ -100,18 +102,16 @@ 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 config_table_pa = 0;
- unsigned int config_table_len;
+ unsigned long cfg_tbl_pa = 0;
+ unsigned int cfg_tbl_len;
bool efi_64;
int ret;

- ret = efi_get_conf_table(boot_params, &config_table_pa,
- &config_table_len, &efi_64);
- if (ret || !config_table_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.");

- return __efi_get_rsdp_addr(config_table_pa, config_table_len,
- 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 16ff5cb9a1fb..7ed31b943c04 100644
--- a/arch/x86/boot/compressed/efi.c
+++ b/arch/x86/boot/compressed/efi.c
@@ -12,14 +12,14 @@
#include <asm/efi.h>

/* Get vendor table address/guid from EFI config table at the given index */
-static int get_vendor_table(void *conf_table, unsigned int idx,
+static int get_vendor_table(void *cfg_tbl, unsigned int idx,
unsigned long *vendor_table_pa,
efi_guid_t *vendor_table_guid,
bool efi_64)
{
if (efi_64) {
efi_config_table_64_t *table_entry =
- (efi_config_table_64_t *)conf_table + idx;
+ (efi_config_table_64_t *)cfg_tbl + idx;

if (!IS_ENABLED(CONFIG_X86_64) &&
table_entry->table >> 32) {
@@ -32,7 +32,7 @@ static int get_vendor_table(void *conf_table, unsigned int idx,

} else {
efi_config_table_32_t *table_entry =
- (efi_config_table_32_t *)conf_table + idx;
+ (efi_config_table_32_t *)cfg_tbl + idx;

*vendor_table_pa = table_entry->table;
*vendor_table_guid = table_entry->guid;
@@ -45,27 +45,25 @@ static int get_vendor_table(void *conf_table, unsigned int idx,
* Given EFI config table, search it for the physical address of the vendor
* table associated with GUID.
*
- * @conf_table: pointer to EFI configuration table
- * @conf_table_len: number of entries in EFI configuration table
+ * @cfg_tbl: 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_table_pa: location to store physical address of vendor table
*
* Returns 0 on success. On error, return params are left unchanged.
*/
-int
-efi_find_vendor_table(unsigned long conf_table_pa, unsigned int conf_table_len,
- efi_guid_t guid, bool efi_64,
- unsigned long *vendor_table_pa)
+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_table_pa)
{
unsigned int i;

- for (i = 0; i < conf_table_len; i++) {
+ for (i = 0; i < cfg_tbl_len; i++) {
unsigned long vendor_table_pa_tmp;
efi_guid_t vendor_table_guid;
int ret;

- if (get_vendor_table((void *)conf_table_pa, i,
+ if (get_vendor_table((void *)cfg_tbl_pa, i,
&vendor_table_pa_tmp,
&vendor_table_guid, efi_64))
return -EINVAL;
@@ -88,9 +86,8 @@ efi_find_vendor_table(unsigned long conf_table_pa, unsigned int conf_table_len,
*
* Returns 0 on success. On error, return params are left unchanged.
*/
-int
-efi_get_system_table(struct boot_params *boot_params,
- unsigned long *sys_table_pa, bool *is_efi_64)
+int efi_get_system_table(struct boot_params *boot_params, unsigned long *sys_table_pa,
+ bool *is_efi_64)
{
unsigned long sys_table;
struct efi_info *ei;
@@ -137,22 +134,19 @@ efi_get_system_table(struct boot_params *boot_params,
* address EFI configuration table.
*
* @boot_params: pointer to boot_params
- * @conf_table_pa: location to store physical address of config table
- * @conf_table_len: location to store number of config table entries
+ * @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 *conf_table_pa,
- unsigned int *conf_table_len,
- 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)
{
unsigned long sys_table_pa = 0;
int ret;

- if (!conf_table_pa || !conf_table_len || !is_efi_64)
+ if (!cfg_tbl_pa || !cfg_tbl_len || !is_efi_64)
return -EINVAL;

ret = efi_get_system_table(boot_params, &sys_table_pa, is_efi_64);
@@ -164,14 +158,14 @@ efi_get_conf_table(struct boot_params *boot_params,
efi_system_table_64_t *stbl =
(efi_system_table_64_t *)sys_table_pa;

- *conf_table_pa = stbl->tables;
- *conf_table_len = stbl->nr_tables;
+ *cfg_tbl_pa = stbl->tables;
+ *cfg_tbl_len = stbl->nr_tables;
} else {
efi_system_table_32_t *stbl =
(efi_system_table_32_t *)sys_table_pa;

- *conf_table_pa = stbl->tables;
- *conf_table_len = stbl->nr_tables;
+ *cfg_tbl_pa = stbl->tables;
+ *cfg_tbl_len = stbl->nr_tables;
}

return 0;

--
Regards/Gruss,
Boris.