linux-kernel - Re: [PATCH v2 2/2] x86, kexec_file_load: make it work with efi=noruntime or efi=old

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Date:   Wed, 16 Jan 2019 00:10:05 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Kairui Song <kasong@...hat.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, x86@...nel.org, dyoung@...hat.com, bhe@...hat.com,
        kexec@...ts.infradead.org, akpm@...ux-foundation.org,
        robert.moore@...el.com, erik.schmauss@...el.com,
        rafael.j.wysocki@...el.com, lenb@...nel.org
Subject: Re: [PATCH v2 2/2] x86, kexec_file_load: make it work with
 efi=noruntime or efi=old_map

On Tue, Jan 15, 2019 at 05:58:34PM +0800, Kairui Song wrote:
> When efi=noruntime or efi=oldmap is used, EFI services won't be available
> in the second kernel, therefore the second kernel will not be able to get
> the ACPI RSDP address from firmware by calling EFI services and won't
> boot. Previously we are expecting the user to set the acpi_rsdp=<addr>
> on kernel command line for second kernel as there was no way to pass RSDP
> address to second kernel.
> 
> After commit e6e094e053af ('x86/acpi, x86/boot: Take RSDP address from
> boot params if available'), now it's possible to set an acpi_rsdp_addr
> parameter in the boot_params passed to second kernel, this commit make
> use of it, detect and set the RSDP address when it's required for second
> kernel to boot.
> 
> Tested with an EFI enabled KVM VM with efi=noruntime.
> 
> Suggested-by: Dave Young <dyoung@...hat.com>
> Signed-off-by: Kairui Song <kasong@...hat.com>
> ---
>  arch/x86/kernel/kexec-bzimage64.c | 21 +++++++++++++++++++++
>  drivers/acpi/acpica/tbxfroot.c    |  3 +--
>  include/acpi/acpixf.h             |  2 +-
>  3 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 53917a3ebf94..0a90dcbd041f 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -20,6 +20,7 @@
>  #include <linux/mm.h>
>  #include <linux/efi.h>
>  #include <linux/verification.h>
> +#include <linux/acpi.h>
>  
>  #include <asm/bootparam.h>
>  #include <asm/setup.h>
> @@ -255,8 +256,28 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
>  	/* Setup EFI state */
>  	setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
>  			efi_setup_data_offset);
> +
> +#ifdef CONFIG_ACPI
> +	/* Setup ACPI RSDP pointer in case EFI is not available in second kernel */
> +	if (!acpi_disabled && (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_OLD_MEMMAP))) {
> +		/* Copied from acpi_os_get_root_pointer accordingly */
> +		params->acpi_rsdp_addr = boot_params.acpi_rsdp_addr;
> +		if (!params->acpi_rsdp_addr) {
> +			if (efi_enabled(EFI_CONFIG_TABLES)) {
> +				if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
> +					params->acpi_rsdp_addr = efi.acpi20;
> +				else if (efi.acpi != EFI_INVALID_TABLE_ADDR)
> +					params->acpi_rsdp_addr = efi.acpi;
> +			} else if (IS_ENABLED(CONFIG_ACPI_LEGACY_TABLES_LOOKUP)) {
> +				acpi_find_root_pointer(&params->acpi_rsdp_addr);
> +			}
> +		}
> +		if (!params->acpi_rsdp_addr)
> +			pr_warn("RSDP is not available for second kernel\n");
> +	}
>  #endif

Amazing the amount of ACPI RDSP parsing and fiddling patches flying
around these days...

In any case, this needs to be synchronized with:

https://lkml.kernel.org/r/20190107032243.25324-1-fanc.fnst@cn.fujitsu.com

and checked whether the above can be used instead of sprinkling of ACPI
parsing code left and right.

Thx.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.