On Wed, Jun 07, 2023 at 05:26:12AM -0700, Ard Biesheuvel wrote:
> [ Upstream commit eb684408f3ea4856639675d6465f0024e498e4b1 ]
>
> Instead of using the SMBIOS type 1 record 'family' field, which is often
> modified by OEMs, use the type 4 'processor ID' and 'processor version'
> fields, which are set to a small set of probe-able values on all known
> Ampere EFI systems in the field.
>
> Fixes: 550b33cfd4452968 ("arm64: efi: Force the use of ...")
> Tested-by: Andrea Righi <andrea.righi@xxxxxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Where did Sasha sign off on this?
> Signed-off-by: Jeremi Piotrowski <jpiotrowski@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/firmware/efi/libstub/arm64-stub.c | 39 ++++++++++++++++-----
> drivers/firmware/efi/libstub/efistub.h | 41 +++++++++++++++++++++--
> drivers/firmware/efi/libstub/smbios.c | 13 +++++--
> 3 files changed, 80 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
> index 42282c5c3fe6..e2f90566b291 100644
> --- a/drivers/firmware/efi/libstub/arm64-stub.c
> +++ b/drivers/firmware/efi/libstub/arm64-stub.c
> @@ -17,20 +17,43 @@
>
> static bool system_needs_vamap(void)
> {
> - const u8 *type1_family = efi_get_smbios_string(1, family);
> + const struct efi_smbios_type4_record *record;
> + const u32 __aligned(1) *socid;
> + const u8 *version;
>
> /*
> * Ampere eMAG, Altra, and Altra Max machines crash in SetTime() if
> - * SetVirtualAddressMap() has not been called prior.
> + * SetVirtualAddressMap() has not been called prior. Most Altra systems
> + * can be identified by the SMCCC soc ID, which is conveniently exposed
> + * via the type 4 SMBIOS records. Otherwise, test the processor version
> + * field. eMAG systems all appear to have the processor version field
> + * set to "eMAG".
> */
> - if (!type1_family || (
> - strcmp(type1_family, "eMAG") &&
> - strcmp(type1_family, "Altra") &&
> - strcmp(type1_family, "Altra Max")))
> + record = (struct efi_smbios_type4_record *)efi_get_smbios_record(4);
> + if (!record)
> return false;
>
> - efi_warn("Working around broken SetVirtualAddressMap()\n");
> - return true;
> + socid = (u32 *)record->processor_id;
> + switch (*socid & 0xffff000f) {
> + static char const altra[] = "Ampere(TM) Altra(TM) Processor";
> + static char const emag[] = "eMAG";
> +
> + default:
> + version = efi_get_smbios_string(&record->header, 4,
> + processor_version);
> + if (!version || (strncmp(version, altra, sizeof(altra) - 1) &&
> + strncmp(version, emag, sizeof(emag) - 1)))
> + break;
> +
> + fallthrough;
> +
> + case 0x0a160001: // Altra
> + case 0x0a160002: // Altra Max
> + efi_warn("Working around broken SetVirtualAddressMap()\n");
> + return true;
> + }
> +
> + return false;
> }
>
> efi_status_t check_platform_features(void)
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 900df67a2078..970e86e3aab0 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -983,6 +983,8 @@ struct efi_smbios_record {
> u16 handle;
> };
>
> +const struct efi_smbios_record *efi_get_smbios_record(u8 type);
> +
> struct efi_smbios_type1_record {
> struct efi_smbios_record header;
>
> @@ -996,13 +998,46 @@ struct efi_smbios_type1_record {
> u8 family;
> };
>
> -#define efi_get_smbios_string(__type, __name) ({ \
> +struct efi_smbios_type4_record {
> + struct efi_smbios_record header;
> +
> + u8 socket;
> + u8 processor_type;
> + u8 processor_family;
> + u8 processor_manufacturer;
> + u8 processor_id[8];
> + u8 processor_version;
> + u8 voltage;
> + u16 external_clock;
> + u16 max_speed;
> + u16 current_speed;
> + u8 status;
> + u8 processor_upgrade;
> + u16 l1_cache_handle;
> + u16 l2_cache_handle;
> + u16 l3_cache_handle;
> + u8 serial_number;
> + u8 asset_tag;
> + u8 part_number;
> + u8 core_count;
> + u8 enabled_core_count;
> + u8 thread_count;
> + u16 processor_characteristics;
> + u16 processor_family2;
> + u16 core_count2;
> + u16 enabled_core_count2;
> + u16 thread_count2;
> + u16 thread_enabled;
> +};
> +
> +#define efi_get_smbios_string(__record, __type, __name) ({ \
> int size = sizeof(struct efi_smbios_type ## __type ## _record); \
> int off = offsetof(struct efi_smbios_type ## __type ## _record, \
> __name); \
> - __efi_get_smbios_string(__type, off, size); \
> + __efi_get_smbios_string((__record), __type, off, size); \
> })
>
> -const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize);
> +const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,
> + u8 type, int offset, int recsize);
>
> #endif
> diff --git a/drivers/firmware/efi/libstub/smbios.c b/drivers/firmware/efi/libstub/smbios.c
> index aadb422b9637..f9c159c28f46 100644
> --- a/drivers/firmware/efi/libstub/smbios.c
> +++ b/drivers/firmware/efi/libstub/smbios.c
> @@ -22,19 +22,28 @@ struct efi_smbios_protocol {
> u8 minor_version;
> };
>
> -const u8 *__efi_get_smbios_string(u8 type, int offset, int recsize)
> +const struct efi_smbios_record *efi_get_smbios_record(u8 type)
> {
> struct efi_smbios_record *record;
> efi_smbios_protocol_t *smbios;
> efi_status_t status;
> u16 handle = 0xfffe;
> - const u8 *strtable;
>
> status = efi_bs_call(locate_protocol, &EFI_SMBIOS_PROTOCOL_GUID, NULL,
> (void **)&smbios) ?:
> efi_call_proto(smbios, get_next, &handle, &type, &record, NULL);
> if (status != EFI_SUCCESS)
> return NULL;
> + return record;
> +}
> +
> +const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,
> + u8 type, int offset, int recsize)
> +{
> + const u8 *strtable;
> +
> + if (!record)
> + return NULL;
>
> strtable = (u8 *)record + record->length;
> for (int i = 1; i < ((u8 *)record)[offset]; i++) {
> --
> 2.30.2
>
