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

Junichi Nomura
2019-03-28T04:21:34Z

On 2019/03/27 10:48, bhe@redhat.com wrote:
>>> So efi_get_rsdp_addr() needs to be refactored in such a way so that at
>>> least the loop towards the end gets carved out into a separate function
>>> - __efi_get_rsdp_addr() or so - which gets config_tables, nr_tables and
>>> size as arguments and finds the RSDP address in the kexec-ed kernel.
>>
>> You need to carve out the loop at the end and make it into a separate
>> __efi_get_rsdp_addr() function which gets the physical or the virtual
>> address.
>
> I guess Boris is suggesting code like below. Please correct me if I am
> wrong.
>
> static acpi_physical_address _efi_get_rsdp_addr(efi_config_table tbl, ...)
> {
> /* Get EFI tables from systab. */
> for (i = 0; i < nr_tables; i++) {
> ...
> }
> return rsdp_addr;
> }
>
> static acpi_physical_address efi_get_rsdp_addr(void)
> {
> ...
> /* Get systab from boot params. */
> ...
> /* Handle EFI bitness properly */
> ...
> return _efi_get_rsdp_addr();
> }
>
>
> static acpi_physical_address kexec_get_rsdp_addr(void)
> {
> if (!is_kexec_booted)
> return 0;
>
> efi_get_setup_data_addr();
> ...
> /* Handle EFI bitness properly */
> ...
> return _efi_get_rsdp_addr();
> }

I still don't get it... We still need systab for kexec case as well
to get nr_tables. Don't we?

> acpi_physical_address get_rsdp_addr(void)
> {
> acpi_physical_address pa;
>
> pa = get_acpi_rsdp();
>
> if (!pa)
> pa = boot_params->acpi_rsdp_addr;
>
>
> /**
> /*I think here we should check if it's kexec booted firstly.
> * Skip it if not kexec. this can avoid the wrong kexec virt
> * addr parsing./
> if (!pa)
> pa = kexec_get_rdsp_addr(); <--- new function
>
> if (!pa)
> pa = efi_get_rsdp_addr();
>

Shouldn't t efi_get_rsdp_addr() check "is_kexec_booted" and exit
early so that it never tries to use virtual config_tables pointer
if for some unknown resason kexec_get_rsdp_addr() failed.

Currently I check "is_kexec_booted" by subset of efi_get_setup_data_addr().
Do you know a simpler way to check "is_kexec_booted"?

> if (!pa)
> pa = bios_get_rsdp_addr();
>
> return pa;
> }

--
Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.