linux-kernel - Re: [PATCH v3 1/3] x86, kexec_file_load: Don't setup EFI info if EFI runtime is not enabled

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Date:   Fri, 25 Jan 2019 10:53:46 +0800
From:   Dave Young <dyoung@...hat.com>
To:     Kairui Song <kasong@...hat.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, x86@...nel.org, 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,
        fanc.fnst@...fujitsu.com, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v3 1/3] x86, kexec_file_load: Don't setup EFI info if EFI
 runtime is not enabled

On 01/18/19 at 07:13pm, Kairui Song wrote:
> Currently with "efi=noruntime" in kernel command line, calling
> kexec_file_load will raise below problem:
> 
> [   97.967067] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> [   97.967894] #PF error: [normal kernel read fault]
> ...
> [   97.980456] Call Trace:
> [   97.980724]  efi_runtime_map_copy+0x28/0x30
> [   97.981267]  bzImage64_load+0x688/0x872
> [   97.981794]  arch_kexec_kernel_image_load+0x6d/0x70
> [   97.982441]  kimage_file_alloc_init+0x13e/0x220
> [   97.983035]  __x64_sys_kexec_file_load+0x144/0x290
> [   97.983586]  do_syscall_64+0x55/0x1a0
> [   97.983962]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> When efi runtime is not enabled, efi memmap is not mapped, so just skip
> EFI info setup.
> 
> Suggested-by: Dave Young <dyoung@...hat.com>
> Signed-off-by: Kairui Song <kasong@...hat.com>
> ---
>  arch/x86/kernel/kexec-bzimage64.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index 2c007abd3d40..097f52fb02e3 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -167,6 +167,9 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
>  	struct efi_info *current_ei = &boot_params.efi_info;
>  	struct efi_info *ei = &params->efi_info;
>  
> +	if (!efi_enabled(EFI_RUNTIME_SERVICES))
> +		return 0;
> +
>  	if (!current_ei->efi_memmap_size)
>  		return 0;
>  
> -- 
> 2.20.1
> 

Patch 1/3 looks good to me, 2-3 should depend on Chao's early rsdp parsing according
to Boris.

Acked-by: Dave Young <dyoung@...hat.com>

Thanks
Dave