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    Subject[PATCH v12 28/46] x86/compressed/acpi: Move EFI kexec handling into common code
    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.

    In this instance, the current acpi.c kexec handling is mainly used to
    get the alternative EFI config table address provided by kexec via a
    setup_data entry of type SETUP_EFI. If not present, the code then falls
    back to normal EFI config table address provided by EFI system table.
    This would need to be done by all call-sites attempting to access the
    EFI config table, so just have efi_get_conf_table() handle that
    automatically.

    Signed-off-by: Michael Roth <michael.roth@amd.com>
    Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    ---
    arch/x86/boot/compressed/acpi.c | 59 ---------------------------------
    arch/x86/boot/compressed/efi.c | 46 ++++++++++++++++++++++++-
    2 files changed, 45 insertions(+), 60 deletions(-)

    diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
    index b0c1dffc5510..64b172dabd5c 100644
    --- a/arch/x86/boot/compressed/acpi.c
    +++ b/arch/x86/boot/compressed/acpi.c
    @@ -47,57 +47,6 @@ __efi_get_rsdp_addr(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len)
    return 0;
    }

    -/* EFI/kexec support is 64-bit only. */
    -#ifdef CONFIG_X86_64
    -static struct efi_setup_data *get_kexec_setup_data_addr(void)
    -{
    - struct setup_data *data;
    - u64 pa_data;
    -
    - pa_data = boot_params->hdr.setup_data;
    - while (pa_data) {
    - data = (struct setup_data *)pa_data;
    - if (data->type == SETUP_EFI)
    - return (struct efi_setup_data *)(pa_data + sizeof(struct setup_data));
    -
    - pa_data = data->next;
    - }
    - return NULL;
    -}
    -
    -static acpi_physical_address kexec_get_rsdp_addr(void)
    -{
    - efi_system_table_64_t *systab;
    - struct efi_setup_data *esd;
    - struct efi_info *ei;
    - enum efi_type et;
    -
    - esd = (struct efi_setup_data *)get_kexec_setup_data_addr();
    - if (!esd)
    - return 0;
    -
    - if (!esd->tables) {
    - debug_putstr("Wrong kexec SETUP_EFI data.\n");
    - return 0;
    - }
    -
    - et = efi_get_type(boot_params);
    - if (et != EFI_TYPE_64) {
    - debug_putstr("Unexpected kexec EFI environment (expected 64-bit EFI).\n");
    - return 0;
    - }
    -
    - /* Get systab from boot params. */
    - systab = (efi_system_table_64_t *)efi_get_system_table(boot_params);
    - if (!systab)
    - error("EFI system table not found in kexec boot_params.");
    -
    - return __efi_get_rsdp_addr((unsigned long)esd->tables, systab->nr_tables);
    -}
    -#else
    -static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
    -#endif /* CONFIG_X86_64 */
    -
    static acpi_physical_address efi_get_rsdp_addr(void)
    {
    #ifdef CONFIG_EFI
    @@ -210,14 +159,6 @@ acpi_physical_address get_rsdp_addr(void)

    pa = boot_params->acpi_rsdp_addr;

    - /*
    - * Try to get EFI data from setup_data. This can happen when we're a
    - * kexec'ed kernel and kexec(1) has passed all the required EFI info to
    - * us.
    - */
    - if (!pa)
    - pa = kexec_get_rsdp_addr();
    -
    if (!pa)
    pa = efi_get_rsdp_addr();

    diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
    index f8d26db22659..ff2e2eaba1d4 100644
    --- a/arch/x86/boot/compressed/efi.c
    +++ b/arch/x86/boot/compressed/efi.c
    @@ -78,6 +78,46 @@ unsigned long efi_get_system_table(struct boot_params *bp)
    return sys_tbl_pa;
    }

    +/*
    + * EFI config table address changes to virtual address after boot, which may
    + * not be accessible for the kexec'd kernel. To address this, kexec provides
    + * the initial physical address via a struct setup_data entry, which is
    + * checked for here, along with some sanity checks.
    + */
    +static struct efi_setup_data *get_kexec_setup_data(struct boot_params *bp,
    + enum efi_type et)
    +{
    +#ifdef CONFIG_X86_64
    + struct efi_setup_data *esd = NULL;
    + struct setup_data *data;
    + u64 pa_data;
    +
    + pa_data = bp->hdr.setup_data;
    + while (pa_data) {
    + data = (struct setup_data *)pa_data;
    + if (data->type == SETUP_EFI) {
    + esd = (struct efi_setup_data *)(pa_data + sizeof(struct setup_data));
    + break;
    + }
    +
    + pa_data = data->next;
    + }
    +
    + /*
    + * Original ACPI code falls back to attempting normal EFI boot in these
    + * cases, so maintain existing behavior by indicating non-kexec
    + * environment to the caller, but print them for debugging.
    + */
    + if (esd && !esd->tables) {
    + debug_putstr("kexec EFI environment missing valid configuration table.\n");
    + return NULL;
    + }
    +
    + return esd;
    +#endif
    + return NULL;
    +}
    +
    /**
    * efi_get_conf_table - Given a pointer to boot_params, locate and return the physical
    * address of EFI configuration table.
    @@ -106,8 +146,12 @@ int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
    et = efi_get_type(bp);
    if (et == EFI_TYPE_64) {
    efi_system_table_64_t *stbl = (efi_system_table_64_t *)sys_tbl_pa;
    + struct efi_setup_data *esd;

    - *cfg_tbl_pa = stbl->tables;
    + /* kexec provides an alternative EFI conf table, check for it. */
    + esd = get_kexec_setup_data(bp, et);
    +
    + *cfg_tbl_pa = esd ? esd->tables : stbl->tables;
    *cfg_tbl_len = stbl->nr_tables;
    } else if (et == EFI_TYPE_32) {
    efi_system_table_32_t *stbl = (efi_system_table_32_t *)sys_tbl_pa;
    --
    2.25.1
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