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    Subject[PATCH v11 27/45] x86/compressed/acpi: Move EFI vendor table lookup to helper
    Date
    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 | 68 +++++++++++--------------------
    arch/x86/boot/compressed/efi.c | 72 +++++++++++++++++++++++++++++++++
    arch/x86/boot/compressed/misc.h | 13 ++++++
    3 files changed, 108 insertions(+), 45 deletions(-)

    diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
    index 9a824af69961..b0c1dffc5510 100644
    --- a/arch/x86/boot/compressed/acpi.c
    +++ b/arch/x86/boot/compressed/acpi.c
    @@ -20,48 +20,31 @@
    */
    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)
    {
    - 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;
    - }
    + unsigned long rsdp_addr;
    + 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.
    + */
    + rsdp_addr = efi_find_vendor_table(boot_params, cfg_tbl_pa, cfg_tbl_len,
    + ACPI_20_TABLE_GUID);
    + if (rsdp_addr)
    + return (acpi_physical_address)rsdp_addr;
    +
    + /* No ACPI_20_TABLE_GUID found, fallback to ACPI_TABLE_GUID. */
    + rsdp_addr = efi_find_vendor_table(boot_params, cfg_tbl_pa, cfg_tbl_len,
    + ACPI_TABLE_GUID);
    + if (rsdp_addr)
    + return (acpi_physical_address)rsdp_addr;
    +
    + debug_putstr("Error getting RSDP address.\n");
    #endif
    - return rsdp_addr;
    + return 0;
    }

    /* EFI/kexec support is 64-bit only. */
    @@ -109,7 +92,7 @@ static acpi_physical_address kexec_get_rsdp_addr(void)
    if (!systab)
    error("EFI system table not found in kexec boot_params.");

    - return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables, true);
    + return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables);
    }
    #else
    static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
    @@ -123,15 +106,10 @@ static acpi_physical_address efi_get_rsdp_addr(void)
    unsigned long systab_pa;
    unsigned int nr_tables;
    enum efi_type et;
    - bool efi_64;
    int ret;

    et = efi_get_type(boot_params);
    - if (et == EFI_TYPE_64)
    - efi_64 = true;
    - else if (et == EFI_TYPE_32)
    - efi_64 = false;
    - else
    + if (et == EFI_TYPE_NONE)
    return 0;

    systab_pa = efi_get_system_table(boot_params);
    @@ -142,7 +120,7 @@ static acpi_physical_address efi_get_rsdp_addr(void)
    if (ret || !cfg_tbl_pa)
    error("EFI config table not found.");

    - return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len, efi_64);
    + return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len);
    #else
    return 0;
    #endif
    diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
    index 70acddbbe7af..f8d26db22659 100644
    --- a/arch/x86/boot/compressed/efi.c
    +++ b/arch/x86/boot/compressed/efi.c
    @@ -120,3 +120,75 @@ int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,

    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,
    + enum efi_type et)
    +{
    + if (et == EFI_TYPE_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 if (et == EFI_TYPE_32) {
    + 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;
    + } else {
    + return -EINVAL;
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * efi_find_vendor_table - Given EFI config table, search it for the physical
    + * address of the vendor table associated with GUID.
    + *
    + * @bp: pointer to boot_params
    + * @cfg_tbl_pa: pointer to EFI configuration table
    + * @cfg_tbl_len: number of entries in EFI configuration table
    + * @guid: GUID of vendor table
    + *
    + * Return: vendor table address on success. On error, return 0.
    + */
    +unsigned long efi_find_vendor_table(struct boot_params *bp,
    + unsigned long cfg_tbl_pa,
    + unsigned int cfg_tbl_len,
    + efi_guid_t guid)
    +{
    + enum efi_type et;
    + unsigned int i;
    +
    + et = efi_get_type(bp);
    + if (et == EFI_TYPE_NONE)
    + return 0;
    +
    + for (i = 0; i < cfg_tbl_len; i++) {
    + unsigned long vendor_tbl_pa;
    + efi_guid_t vendor_tbl_guid;
    + int ret;
    +
    + ret = get_vendor_table((void *)cfg_tbl_pa, i,
    + &vendor_tbl_pa,
    + &vendor_tbl_guid, et);
    + if (ret)
    + return 0;
    +
    + if (!efi_guidcmp(guid, vendor_tbl_guid))
    + return vendor_tbl_pa;
    + }
    +
    + return 0;
    +}
    diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
    index 8815af092a10..ba538af37e90 100644
    --- a/arch/x86/boot/compressed/misc.h
    +++ b/arch/x86/boot/compressed/misc.h
    @@ -23,6 +23,7 @@
    #include <linux/screen_info.h>
    #include <linux/elf.h>
    #include <linux/io.h>
    +#include <linux/efi.h>
    #include <asm/page.h>
    #include <asm/boot.h>
    #include <asm/bootparam.h>
    @@ -188,6 +189,10 @@ enum efi_type efi_get_type(struct boot_params *bp);
    unsigned long efi_get_system_table(struct boot_params *bp);
    int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
    unsigned int *cfg_tbl_len);
    +unsigned long efi_find_vendor_table(struct boot_params *bp,
    + unsigned long cfg_tbl_pa,
    + unsigned int cfg_tbl_len,
    + efi_guid_t guid);
    #else
    static inline enum efi_type efi_get_type(struct boot_params *bp)
    {
    @@ -205,6 +210,14 @@ static inline int efi_get_conf_table(struct boot_params *bp,
    {
    return -ENOENT;
    }
    +
    +static inline unsigned long efi_find_vendor_table(struct boot_params *bp,
    + unsigned long cfg_tbl_pa,
    + unsigned int cfg_tbl_len,
    + efi_guid_t guid)
    +{
    + return 0;
    +}
    #endif /* CONFIG_EFI */

    #endif /* BOOT_COMPRESSED_MISC_H */
    --
    2.25.1
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