Re: [PATCH v2] x86/boot: Use EFI setup data if provided

bhe
2019-03-28T23:11:09Z

On 03/28/19 at 07:43am, Junichi Nomura wrote:
> On 2019/03/28 15:43, bhe@redhat.com wrote:
> > On 03/28/19 at 04:17am, Junichi Nomura wrote:
> >> I still don't get it... We still need systab for kexec case as well
> >> to get nr_tables. Don't we?
> >
> > Yes, simpler.
> >
> > As Dave replied in another mail, efi/kexec is only added for x86_64. See
> > how it does in setup_linux_system_parameters() of kexec_tools utility,
> > and we only have bzImage64 handling in kernel for kexec_file loading,
> > see prepare_add_efi_setup_data().
> >
> > You may only need to get kexec ei_info to use directly.
>
> OK, let me try. How does this look?

Yes, it looks great. Thanks.

Some tiny concenrns added in inline comments, please check.

>
> Commit 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in
> boot_params") broke kexec boot on EFI systems. efi_get_rsdp_addr()
> in the early parsing code tries to search RSDP from EFI table but
> that will crash because the table address is virtual when the kernel
> was booted by kexec.
>
> Since kexec(1) provides physical address of the table via efi_setup_data,
> early boot code of kexec-ed kernel should look for setup_data in the same
> way as efi_systab_init() in arch/x86/platform/efi/efi.c does.
>
> Fixes: 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in boot_params")
> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
> Cc: Chao Fan <fanc.fnst@cn.fujitsu.com>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Baoquan He <bhe@redhat.com>
>
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -44,17 +44,106 @@ static acpi_physical_address get_acpi_rsdp(void)
> return addr;
> }
>
> +static unsigned long efi_get_kexec_setup_data_addr(void)
> +{
> +#ifdef CONFIG_EFI
> + 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 pa_data + sizeof(struct setup_data);
> + pa_data = data->next;
> + }
> +#endif
> + return 0;
> +}
> +
> /* Search EFI system tables for RSDP. */
> -static acpi_physical_address efi_get_rsdp_addr(void)
> +static acpi_physical_address __efi_get_rsdp_addr(unsigned long config_tables, unsigned int nr_tables, int size, bool efi_64)

Here parameter 'size' and 'efi_64' seems a little duplicated on
functionality. Only passing efi_64 can deduce the size? Personal
opinion.

> {
> acpi_physical_address rsdp_addr = 0;
>
> #ifdef CONFIG_EFI
> - unsigned long systab, systab_tables, config_tables;
> + int i;
> +
> + /* Get EFI tables from systab. */
> + for (i = 0; i < nr_tables; i++) {
> + acpi_physical_address table;
> + efi_guid_t guid;
> +
> + config_tables += size;
> +
> + if (efi_64) {
> + efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables;
> +
> + 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;
> +
> + guid = tbl->guid;
> + table = tbl->table;
> + }
> +
> + if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
> + rsdp_addr = table;
> + else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
> + return table;
> + }
> +#endif
> + return rsdp_addr;
> +}
> +

It might be worth adding code comments here to tell why we only care
about 64bit kexec booting?

> +static acpi_physical_address kexec_get_rsdp_addr(void)
> +{
> +#ifdef CONFIG_EFI
> + struct efi_setup_data *esd;
> + efi_system_table_64_t *systab;
> + struct efi_info *ei;
> + char *sig;
> +
> + esd = (struct efi_setup_data *) efi_get_kexec_setup_data_addr();
> + if (!esd)
> + return 0;
> + if (!esd->tables) {
> + debug_putstr("Wrong kexec SETUP_EFI data.\n");
> + return 0;
> + }
> +
> + ei = &boot_params->efi_info;
> + sig = (char *)&ei->efi_loader_signature;
> + if (strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
> + debug_putstr("Wrong EFI loader signature.\n");
> + return 0;
> + }
> +
> + /* Get systab from boot params. */
> + systab = (efi_system_table_64_t *) (ei->efi_systab | ((__u64)ei->efi_systab_hi << 32));
> + if (!systab)
> + error("EFI system table not found.");
> +
> + return __efi_get_rsdp_addr((unsigned long) esd->tables, systab->nr_tables, sizeof(efi_config_table_64_t), true);
> +#else
> + return 0;
> +#endif
> +}
> +
> +static acpi_physical_address efi_get_rsdp_addr(void)
> +{
> +#ifdef CONFIG_EFI
> + unsigned long systab, config_tables;
> unsigned int nr_tables;
> struct efi_info *ei;
> bool efi_64;
> - int size, i;
> + int size;
> char *sig;
>
> ei = &boot_params->efi_info;
> @@ -100,37 +189,10 @@ static acpi_physical_address efi_get_rsdp_addr(void)
> if (!config_tables)
> error("EFI config tables not found.");
>
> - /* Get EFI tables from systab. */
> - for (i = 0; i < nr_tables; i++) {
> - acpi_physical_address table;
> - efi_guid_t guid;
> -
> - config_tables += size;
> -
> - if (efi_64) {
> - efi_config_table_64_t *tbl = (efi_config_table_64_t *)config_tables;
> -
> - 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;
> -
> - guid = tbl->guid;
> - table = tbl->table;
> - }
> -
> - if (!(efi_guidcmp(guid, ACPI_TABLE_GUID)))
> - rsdp_addr = table;
> - else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID)))
> - return table;
> - }
> + return __efi_get_rsdp_addr(config_tables, nr_tables, size, efi_64);
> +#else
> + return 0;
> #endif
> - return rsdp_addr;
> }
>
> static u8 compute_checksum(u8 *buffer, u32 length)
> @@ -221,6 +283,9 @@ acpi_physical_address get_rsdp_addr(void)
> pa = boot_params->acpi_rsdp_addr;
>
> if (!pa)
> + pa = kexec_get_rsdp_addr();
> +
> + if (!pa)
> pa = efi_get_rsdp_addr();
>
> if (!pa)