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

Venu Busireddy
2022-01-06T20:34:39Z

On 2021-12-10 09:43:17 -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 | 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
>