Re: [PATCH v8 26/40] x86/compressed/acpi: move EFI vendor table lookup to helper

Venu Busireddy
2022-01-06T20:48:42Z

On 2021-12-10 09:43:18 -0600, 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. 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>

Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>

> ---
> arch/x86/boot/compressed/acpi.c | 50 ++++++++-----------------
> arch/x86/boot/compressed/efi.c | 65 +++++++++++++++++++++++++++++++++
> arch/x86/boot/compressed/misc.h | 9 +++++
> 3 files changed, 90 insertions(+), 34 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> index fea72a1504ff..0670c8f8888a 100644
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -20,46 +20,28 @@
> */
> 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, bool efi_64)
> {
> 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;
> - }
> + 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.
> + */
> + 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;
> }
> diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
> index 08ad517b0731..c1ddc72ef4d9 100644
> --- a/arch/x86/boot/compressed/efi.c
> +++ b/arch/x86/boot/compressed/efi.c
> @@ -112,3 +112,68 @@ 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,
> + bool efi_64)
> +{
> + if (efi_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 {
> + 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;
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * efi_find_vendor_table - Given EFI config table, search it for the physical
> + * address of the vendor table associated with GUID.
> + *
> + * @cfg_tbl_pa: 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_tbl_pa: location to store physical address of vendor table
> + *
> + * Return: 0 on success. On error, return params are left unchanged.
> + */
> +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_tbl_pa)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < cfg_tbl_len; i++) {
> + unsigned long vendor_tbl_pa_tmp;
> + efi_guid_t vendor_tbl_guid;
> + int ret;
> +
> + if (get_vendor_table((void *)cfg_tbl_pa, i,
> + &vendor_tbl_pa_tmp,
> + &vendor_tbl_guid, efi_64))
> + return -EINVAL;
> +
> + if (!efi_guidcmp(guid, vendor_tbl_guid)) {
> + *vendor_tbl_pa = vendor_tbl_pa_tmp;
> + return 0;
> + }
> + }
> +
> + return -ENOENT;
> +}
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index 1c69592e83da..e9fde1482fbe 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -183,6 +183,8 @@ 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);
> +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_tbl_pa);
> #else
> static inline int
> efi_get_system_table(struct boot_params *boot_params,
> @@ -197,6 +199,13 @@ efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
> {
> return -ENOENT;
> }
> +
> +static inline 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_tbl_pa)
> +{
> + return -ENOENT;
> +}
> #endif /* CONFIG_EFI */
>
> #endif /* BOOT_COMPRESSED_MISC_H */
> --
> 2.25.1
>